Common DHCP commandsdhcp client-detectUse dhcp client-detect to enable client offline detection on the DHCP server or DHCP relay agent. Show
Use undo dhcp client-detect to disable client offline detection on the DHCP server or DHCP relay agent. Syntax dhcp client-detect undo dhcp client-detect Default Client offline detection is disabled on the DHCP server or DHCP relay agent. Views Interface view Predefined user roles network-admin mdc-admin Usage guidelines The client offline detection feature on the DHCP server reclaims an assigned IP address and deletes the binding entry when the ARP entry ages out for the IP address. This feature on the DHCP relay agent deletes the related relay entry and sends a RELEASE message to the DHCP server when an ARP entry ages out. Examples # Enable client offline detection. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp client-detect dhcp dscpUse dhcp dscp to set the DSCP value for DHCP packets sent by the DHCP server or the DHCP relay agent. Use undo dhcp dscp to restore the default. Syntax dhcp dscp dscp-value undo dhcp dscp Default The DSCP value is 56 in DHCP packets sent by the DHCP server or the DHCP relay agent. Views System view Predefined user roles network-admin mdc-admin Parameters dscp-value: Specifies the DSCP value for DHCP packets, in the range of 0 to 63. Usage guidelines The DSCP value of a packet specifies the priority level of the packet and affects the transmission priority of the packet. A bigger DSCP value represents a higher priority. Examples # Set the DSCP value to 30 for DHCP packets sent by the DHCP server or the DHCP relay agent. <Sysname> system-view [Sysname] dhcp dscp 30 dhcp enableUse dhcp enable to enable DHCP. Use undo dhcp enable to disable DHCP. Syntax dhcp enable undo dhcp enable Default DHCP is disabled. Views System view Predefined user roles network-admin mdc-admin Usage guidelines DHCP related configuration takes effect only after you enable DHCP. Enable DHCP before you configure the DHCP server or relay agent. Examples # Enable DHCP. <Sysname> system-view [Sysname] dhcp enable dhcp log enableUse dhcp log enable to enable DHCP server logging. Use undo dhcp log enable to disable DHCP server logging. Syntax dhcp log enable undo dhcp log enable Default DHCP server logging is disabled. Views System view Predefined user roles network-admin mdc-admin Usage guidelines This command enables the DHCP server to generate DHCP logs and send them to the information center. For information about the log destination and output rule configuration in the information center, see Network Management and Monitoring Configuration Guide. As a best practice, disable this feature if the log generation affects the device performance or reduces the address allocation efficiency. For example, this situation might occur when a large number of clients frequently come online or go offline. Examples # Enable DHCP server logging. <Sysname> system-view [Sysname] dhcp log enable dhcp selectUse dhcp select to enable the DHCP server or DHCP relay agent on an interface. Use undo dhcp select to disable the DHCP server or DHCP relay agent on an interface. The interface will discard incoming DHCP packets. Syntax dhcp select { relay [ proxy ] | server } undo dhcp select { relay | server } Default The interface operates in the DHCP server mode and responds to DHCP requests with configuration parameters. Views Interface view Predefined user roles network-admin mdc-admin Parameters relay: Enables the DHCP relay agent on the interface. proxy: Enables the DHCP server proxy on the relay agent. server: Enables the DHCP server on the interface. Usage guidelines Before enabling a DHCP server to operate as a DHCP relay agent, use the reset dhcp server ip-in-use command to clear address bindings and authorized ARP entries. These authorized ARP entries might conflict with ARP entries that are created after the DHCP relay agent is enabled. When DHCP server proxy is enabled on the DHCP relay agent, the proxy forwards packets between the DHCP clients and DHCP server. · When receiving DHCP requests from DHCP clients, the proxy forwards them to the DHCP server. · When receiving DHCP responses from the DHCP server, the proxy modifies the DHCP server's IP address in these responses as its own IP address. Examples # Enable the DHCP relay agent on VLAN-interface 2. <Sysname> system-view [Sysname] interface vlan-interface 2 [Sysname-Vlan-interface2] dhcp select relay Related commands dhcp relay server-address dhcp relay source-address dhcp smart-relay enable reset dhcp server ip-in-use DHCP server commandsaddress rangeUse address range to configure an IP address range in a DHCP address pool for dynamic allocation. Use undo address range to restore the default. Syntax address range start-ip-address end-ip-address undo address range Default No IP address range exists. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters start-ip-address: Specifies the start IP address. end-ip-address: Specifies the end IP address. Usage guidelines If no IP address range is specified, all IP addresses in the subnet specified by the network command in address pool view are assignable. If an IP address range is specified, only the IP addresses in the IP address range are assignable. After you use the address range command,you cannot use the network secondary command to specify a secondary subnet in the address pool. If you execute this command multiple times, the most recent configuration takes effect. The address range specified by the address range command must be within the subnet specified by the network command. The addresses outside of the subnet cannot be assigned. Examples # Specify an address range of 192.168.8.1 through 192.168.8.150 in address pool 1. <Sysname> system-view [Sysname] dhcp server ip-pool 1 [Sysname-dhcp-pool-1] address range 192.168.8.1 192.168.8.150 Related commands class dhcp class display dhcp server pool network bims-serverUse bims-server to specify the IP address, port number, and shared key of the BIMS server in a DHCP address pool. Use undo bims-server to restore the default. Syntax bims-server ip ip-address [ port port-number ] sharekey { cipher | simple } string undo bims-server Default No BIMS server information is specified. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip ip-address: Specifies the IP address of the BIMS server. port port-number: Specifies the port number of the BIMS server, in the range of 1 to 65534. cipher: Specifies a key in encrypted form. simple: Specifies a key in plaintext form. For security purposes, the key specified in plaintext form will be stored in encrypted form. string: Specifies the key string. Its plaintext form is a case-sensitive string of 1 to 16 characters. Its encrypted form is a case-sensitive string of 1 to 53 characters. The DHCP client uses the shared key to encrypt packets sent to the BIMS server. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify BIMS server IP address 1.1.1.1, port number 80, and shared key aabbcc in address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] bims-server ip 1.1.1.1 port 80 sharekey simple aabbcc Related commands display dhcp server pool bootfile-nameUse bootfile-name to specify a configuration file name or URL. Use undo bootfile-name to restore the default. Syntax bootfile-name{ bootfile-name | url } undo bootfile-name Default No configuration file name or URL is specified. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters bootfile-name: Specifies the configuration file name, a case-sensitive string of 1 to 63 characters. url: Specifies the HTTP URL of the configuration file. It is a case-sensitive string of 1 to 63 characters. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. To specify a configuration file on a TFTP server, use the bootfile-name argument. To specify a configuration file on an HTTP server, use the url argument. Examples # Specify configuration file name boot.cfg in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] bootfile-name boot.cfg # Specify configuration file URL http://10.1.1.1/boot.cfg in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] bootfile-name http://10.1.1.1/boot.cfg Related commands display dhcp server pool next-server tftp-server domain-name tftp-server ip-address class ip-poolUse class ip-pool to specify a DHCP address pool for a DHCP user class. Use undo class ip-pool to remove the DHCP address pool specified for a DHCP user class. Syntax class class-name ip-pool pool-name undo class class-name ip-pool Default No DHCP address pool is specified for a DHCP user class. Views DHCP policy view Predefined user roles network-admin mdc-admin Parameters class-name: Specifies a DHCP user class by its name, a case-insensitive string of 1 to 63 characters. pool-name: Specifies a DHCP address pool by its name, a case-insensitive string of 1 to 63 characters. Usage guidelines You can specify only one DHCP address pool for a DHCP user class in a DHCP policy. If you execute this command multiple times for a user class, the most recent configuration takes effect. Examples # Specify DHCP address pool pool1 for DHCP user class test in DHCP policy 1. <Sysname> system-view [Sysname] dhcp policy 1 [Sysname-dhcp-policy-1] class test ip-pool pool1 Related commands default ip-pool dhcp policy dhcp server ip-pool class option-groupUse class option-group to specify a DHCP option group for a DHCP user class. Use undo class option-group to remove the configuration. Syntax class class-name option-group option-group-number undo class class-name option-group Default No DHCP option group is specified for a DHCP user class. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters class-name: Specifies a DHCP user class by its name, a case-insensitive string of 1 to 63 characters. option-group-number: Specifies a DHCP option group by its number in the range of 1 to 32768. Usage guidelines When receiving a DHCP-DISCOVER message, the server compares the client against the user classes in the order that they are specified by this command. If a match is found, the server assigns the client the DHCP options in the option group. If multiple matches are found, the server selects option groups by using the following methods: · If the option groups have options in common, the server selects the option group specified for the first matching user class. · If the option groups have different options, the server selects all the matching option groups. You can specify only one option group for a DHCP user class in a DHCP address pool. If you execute this command multiple times for a user class, the most recent configuration takes effect. Examples # Specify DHCP option group 1 for user class user in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] class user option-group 1 Related commands dhcp option-group class rangeUse class range to specify an IP address range for a DHCP user class. Use undo class range to remove the IP address range for the DHCP user class. Syntax class class-name range start-ip-address end-ip-address undo class class-name range Default No IP address range is specified for a DHCP user class. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters class-name: Specifies a DHCP user class name, a case-insensitive string of 1 to 63 characters. If the specified user class does not exist, the DHCP server will not assign the addresses in the address range specified for the user class to any clients. start-ip-address: Specifies the start IP address. end-ip-address: Specifies the end IP address. Usage guidelines The class range command allows you to divide an address range into multiple address ranges for different DHCP user classes. The address range for a user class must be within the primary subnet specified by the network command. If the DHCP client does not match any DHCP user class, the DHCP server selects an address in the IP address range specified by the address range command. If the address range has no assignable IP addresses or no address range is configured, the address allocation fails. After you specify an address range for a user class, you cannot use the network secondary command tospecify a secondary subnet in the address pool. You can specify only one address range for a DHCP user class in an address pool. If you execute this command multiple times for a DHCP user class, the most recent configuration takes effect. Examples # Specify an IP address range of 192.168.8.1 through 192.168.8.150 for DHCP user class user in DHCP address pool 1. <Sysname> system-view [Sysname] dhcp server ip-pool 1 [Sysname-dhcp-pool-1] class user range 192.168.8.1 192.168.8.150 Related commands address range dhcp class display dhcp server pool default ip-poolUse default ip-pool to specify the default DHCP address pool. Use undo default ip-pool to restore the default. Syntax default ip-pool pool-name undo default ip-pool Default No default DHCP address pool is specified. Views DHCP policy view Predefined user roles network-admin mdc-admin Parameters pool-name: Specifies a DHCP address pool by its name, a case-insensitive string of 1 to 63 characters. Usage guidelines In a DHCP policy, the DHCP server uses the default DHCP address pool to assign IP addresses and other parameters to clients that do not match any user classes. If no default address pool is specified or the default address pool does not have assignable IP addresses, the address assignment fails. You can specify only one default address pool in a DHCP policy. If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify DHCP address pool pool1 as the default DHCP address pool in DHCP policy 1. <Sysname> system-view [Sysname] dhcp policy 1 [Sysname-dhcp-policy-1] default ip-pool pool1 Related commands class ip-pool dhcp policy dhcp apply-policyUse dhcp apply-policy to apply a DHCP policy to an interface. Use undo dhcp apply-policy to restore the default. Syntax dhcp apply-policy policy-name undo dhcp apply-policy Default No DHCP policy is applied to an interface. Views Interface view Predefined user roles network-admin mdc-admin Parameters policy-name: Specifies a DHCP policy by its name, a case-insensitive string of 1 to 63 characters. Usage guidelines You can apply only one DHCP policy to an interface. If you execute this command multiple times, the most recent configuration takes effect. Examples # Apply DHCP policy test to VLAN-interface 10. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp apply-policy test Related commands dhcp policy dhcp classUse dhcp class to create a DHCP user class and enter its view, or enter the view of an existing DHCP user class. Use undo dhcp class to delete the specified DHCP user class. Syntax dhcp class class-name undo dhcp class class-name Default No DHCP user classes exist. Views System view Predefined user roles network-admin mdc-admin Parameters class-name: Specifies the name of a DHCP user class, a case-insensitive string of 1 to 63 characters. Usage guidelines In the DHCP user class view, you can use the if-match command to configure match rules to group clients to the user class. Examples # Create DHCP user class test and enter DHCP user class view. <Sysname> system-view [Sysname] dhcp class test [Sysname-dhcp-class-test] Related commands address range class ip-pool class option-group class range dhcp policy if-match dhcp option-groupUse dhcp option-group to create a DHCP option group and enter its view, or enter the view of an existing DHCP option group. Use undo dhcp option-group to delete a DHCP option group. Syntax dhcp option-group option-group-number undo dhcp option-group option-group-number Default No DHCP option groups exist. Views System view Predefined user roles network-admin mdc-admin Parameters option-group-number: Assigns a number to the DHCP option group, in the range of 1 to 32768. Examples # Create DHCP option group 1 and enter DHCP option group view. <Sysname> system-view [Sysname] dhcp option-group 1 [Sysname-dhcp-option-group-1] Related commands class option-group option dhcp policyUse dhcp policy to create a DHCP policy and enter its view, or enter the view of an existing DHCP policy. Use undo dhcp policy to delete a DHCP policy. Syntax dhcp policy policy-name undo dhcp policy policy-name Default No DHCP policies exist. Views System view Predefined user roles network-admin mdc-admin Parameters policy-name: Assigns a name to the DHCP policy. The policy name is a case-insensitive string of 1 to 63 characters. Usage guidelines In DHCP policy view, you can specify address pools for different user classes. Clients matching a user class will obtain IP addresses and other parameters from the specified address pool. For a DHCP policy to take effect, you must apply it to an interface. Examples # Create DHCP policy test and enter its view. <Sysname> system-view [Sysname] dhcp policy test [Sysname-dhcp-policy-test] Related commands class ip-pool default ip-pool dhcp apply-policy dhcp class dhcp server always-broadcastUse dhcp server always-broadcast to enable the DHCP server to broadcast all responses. Use undo dhcp server always-broadcast to restore the default. Syntax dhcp server always-broadcast undo dhcp server always-broadcast Default The DHCP server reads the broadcast flag in a DHCP request to decide whether to broadcast or unicast the response. Views System view Predefined user roles network-admin mdc-admin Usage guidelines This command enables the DHCP server to ignore the broadcast flag in DHCP requests and broadcast all responses. The DHCP server always unicasts a response in the following situations, regardless of whether this command is executed: · The DHCP request is from a DHCP client that has an IP address (the ciaddr field is not 0). · The DHCP request is forwarded by a DHCP relay agent from a DHCP client (the giaddr field is not 0). Examples # Enable the DHCP server to broadcast all responses. <Sysname> system-view [Sysname] dhcp server always-broadcast dhcp server apply ip-poolUse dhcp server apply ip-pool to apply an address pool to an interface. Use undo dhcp server apply ip-pool to restore the default. Syntax dhcp server apply ip-pool pool-name undo dhcp server apply ip-pool Default No address pool is applied to an interface Views Interface view Predefined user roles network-admin mdc-admin Parameters pool-name: Specifies the name of a DHCP address pool, a case-insensitive string of 1 to 63 characters. Usage guidelines Upon receiving a DHCP request from the interface, the DHCP server searches for a static binding for the client from all address pools. If no static binding is found, the server assigns configuration parameters from the address pool applied on the interface to the client. If the address pool has no assignable IP address or does not exist, the DHCP client cannot obtain an IP address. If you execute this command multiple times, the most recent configuration takes effect. Examples # Apply DHCP address pool 0 to VLAN-interface 2. <Sysname> system-view [Sysname] interface vlan-interface 2 [Sysname-Vlan-interface2] dhcp server apply ip-pool 0 Related commands dhcp server ip-pool dhcp server bootp ignoreUse dhcp server bootp ignore to configure the DHCP server to ignore BOOTP requests. Use undo dhcp server bootp ignore to restore the default. Syntax dhcp server bootp ignore undo dhcp server bootp ignore Default The DHCP server does not ignore BOOTP requests. Views System view Predefined user roles network-admin mdc-admin Usage guidelines The lease duration of IP addresses obtained by BOOTP clients is unlimited. For scenarios that do not allow unlimited leases, you can configure the DHCP server to ignore BOOTP requests. Examples # Configure the DHCP server to ignore BOOTP requests. <Sysname> system-view [Sysname] dhcp server bootp ignore dhcp server bootp reply-rfc-1048Use dhcp server bootp reply-rfc-1048 to enable the sending of BOOTP responses in RFC 1048 format. Use undo dhcp server bootp reply-rfc-1048 to disable this feature. Syntax dhcp server bootp reply-rfc-1048 undo dhcp server bootp reply-rfc-1048 Default This feature is disabled. The DHCP server does not process the Vend field of RFC 1048-incompliant requests but copies the Vend field into responses. Views System view Predefined user roles network-admin mdc-admin Usage guidelines Not all BOOTP clients can send requests compliant with RFC 1048. This command enables the DHCP server to fill the Vend field in RFC 1048-compliant format in DHCP responses to RFC 1048-incompliant requests sent by BOOTP clients. This command takes effect only when the BOOTP clients request statically bound addresses. Examples # Enable the sending of BOOTP responses in RFC 1048 format on the DHCP server. <Sysname> system-view [Sysname] dhcp server bootp reply-rfc-1048 dhcp server database filenameUse dhcp server database filename to configure the DHCP server to back up the DHCP bindings to a file. Use undo dhcp server database filename to restore the default. Syntax dhcp server database filename { filename | url url [ username username [ password { cipher | simple } string ] ] } undo dhcp server database filename Default The DHCP server does not back up the DHCP bindings. Views System view Predefined user roles network-admin mdc-admin Parameters filename: Specifies the name of a local backup file. For information about the filename argument, see Fundamentals Configuration Guide. url url: Specifies the URL of a remote backup file, a case-sensitive string of 1 to 255 characters. Do not include a username or password in the URL. username username: Specifies the username for accessing the URL of the remote backup file, a case-sensitive string of 1 to 32 characters. Do not specify this option if a username is not required for accessing the URL of the remote backup file. cipher: Specifies a password in encrypted form. simple: Specifies a password in plaintext form. For security purposes, the password specified in plaintext form will be stored in encrypted form. string: Specifies the password. Its plaintext form is a case-sensitive string of 1 to 32 characters. Its encrypted form is a case-sensitive string of 1 to 73 characters. Do not specify this argument if a password is not required for accessing the URL of the remote backup file. Usage guidelines The command automatically creates the file if you specify a nonexistent file. With this command executed, the DHCP server backs up its bindings immediately and runs auto backup. The server, by default, waits 300 seconds after a binding change to update the backup file. You can use the dhcp server database update interval command to change the waiting time. If no DHCP binding changes, the backup file is not updated. As a best practice, back up the bindings to a remote file. If you use the local storage medium, the frequent erasing and writing might damage the medium and then cause the DHCP server to malfunction. When the backup file is on a remote device, follow these restrictions and guidelines to specify the URL, username, and password: · If the file is on an FTP server, enter URL in the following format: ftp://server address:port/file path, where the port number is optional. · If the file is on a TFTP server, enter URL in the following format: tftp://server address:port/file path, where the port number is optional. · The username and password must be the same as those configured on the FTP server. If the server authenticates only the username, the password can be omitted. · If the IP address of the server is an IPv6 address, enclose the address in a pair of brackets, for example, ftp://[1::1]/database.dhcp. · You can also specify the DNS domain name for the server address field, for example, ftp://company/database.dhcp. Examples # Configure the DHCP server to back up its bindings to file database.dhcp. <Sysname> system-view [Sysname] dhcp server database filename database.dhcp # Configure the DHCP server to back up its bindings to file database.dhcp in the working directory of the FTP server at 10.1.1.1. <Sysname> system-view [Sysname] dhcp server database filename url ftp://10.1.1.1/database.dhcp username 1 password simple 1 Related commands dhcp server database update interval dhcp server database update now dhcp server database update stop dhcp server database update intervalUse dhcp server database update interval to set the waiting time for the DHCP server to update the backup file after a DHCP binding change. Use undo dhcp server database update interval to restore the default. Syntax dhcp server database update interval interval undo dhcp server database update interval Default The DHCP server waits 300 seconds to update the backup file after a DHCP binding change. If no DHCP binding changes, the backup file is not updated. Views System view Predefined user roles network-admin mdc-admin Parameters interval: Specifies the waiting time in the range of 60 to 864000 seconds. Usage guidelines When a DHCP binding is created, updated, or removed, the waiting period starts. The DHCP server updates the backup file when the waiting period is reached. All bindings changed during the period will be saved to the backup file. The waiting time takes effect only after you configure the DHCP binding auto backup by using the dhcp server database filename command. Examples # Set the waiting time to 10 minutes for the DHCP server to update the backup file. <Sysname> system-view [Sysname] dhcp server database update interval 600 Related commands dhcp server database filename dhcp server database update now dhcp server database update stop dhcp server database update nowUse dhcp server database update now to manually save the DHCP bindings to the backup file. Syntax dhcp server database update now Views System view Predefined user roles network-admin mdc-admin Usage guidelines Each time this command is executed, the DHCP bindings are saved to the backup file. For this command to take effect, you must configure the DHCP auto backup by using the dhcp server database filename command. Examples # Manually save the DHCP bindings to the backup file. <Sysname> system-view [Sysname] dhcp server database update now Related commands dhcp server database filename dhcp server database update interval dhcp server database update stop dhcp server database update stopUse dhcp server database update stop to terminate the download of DHCP bindings from the backup file. Syntax dhcp server database update stop Views System view Predefined user roles network-admin mdc-admin Usage guidelines The DHCP server does not provide services during the binding download process. If the connection disconnects during the process, the waiting timeout timer is 60 minutes. When the timer expires, the DHCP server stops waiting and starts providing address allocation services. To enable the DHCP server to provide services without waiting for the connection to be repaired, use this command to terminate the download immediately. The IP addresses associated with the undownloaded bindings will be assigned to clients. Address conflicts might occur. Examples # Terminate the download of the backup DHCP bindings. <Sysname> system-view [Sysname] dhcp server database update stop Related commands dhcp server database filename dhcp server database update interval dhcp server database update now dhcp server forbidden-ipUse dhcp server forbidden-ip to exclude IP addresses from dynamic allocation globally. Use undo dhcp server forbidden-ip to remove the configuration. Syntax dhcp server forbidden-ip start-ip-address [ end-ip-address ] [ vpn-instance vpn-instance-name ] undo dhcp server forbidden-ip start-ip-address [ end-ip-address ] [ vpn-instance vpn-instance-name ] Default No IP addresses are excluded from dynamic allocation globally. Views System view Predefined user roles network-admin mdc-admin Parameters start-ip-address: Specifies the start IP address. end-ip-address: Specifies the end IP address, which cannot be lower than the start-ip-address. If you do not specify this argument, only the start-ip-address is excluded from dynamic allocation. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If the excluded IP addresses belong to the public network, do not specify this option. Usage guidelines The IP addresses of some devices such as the gateway and FTP server cannot be assigned to clients. Use this command to exclude such addresses from dynamic allocation. If the excluded IP address is in a static DHCP binding, the address can still be assigned to the client. The address or address range specified in the undo dhcp server forbidden-ip command must be the same as that specified in the dhcp server forbidden-ip command. To remove an IP address from the specified address range, you must remove the entire address range. You can execute this command multiple times to exclude multiple IP address ranges from dynamic allocation. Examples # Exclude the IP addresses of 10.110.1.1 through 10.110.1.63 from dynamic allocation globally. <Sysname> system-view [Sysname] dhcp server forbidden-ip 10.110.1.1 10.110.1.63 Related commands forbidden-ip static-bind dhcp server ip-poolUse dhcp server ip-pool to create a DHCP address pool and enter its view, or enter the view of an existing DHCP address pool. Use undo dhcp server ip-pool to delete the specified DHCP address pool. Syntax dhcp server ip-pool pool-name undo dhcp server ip-pool pool-name Default No DHCP address pools exist. Views System view Predefined user roles network-admin mdc-admin Parameters pool-name: Specifies a DHCP address pool name, a case-insensitive string of 1 to 63 characters. The pool name uniquely identifies an address pool. Usage guidelines A DHCP address pool is used to store the configuration parameters to be assigned to DHCP clients. Examples # Create a DHCP address pool named pool1. <Sysname> system-view [Sysname] dhcp server ip-pool pool1 [Sysname-dhcp-pool-pool1] Related commands class ip-pool dhcp server apply ip-pool display dhcp server pool dhcp server ping packetsUse dhcp server ping packets to set the maximum number of ping packets. Use undo dhcp server ping packets to restore the default. Syntax dhcp server ping packets number undo dhcp server ping packets Default The maximum number of ping packets is 1. Views System view Predefined user roles network-admin mdc-admin Parameters number: Sets the maximum number of ping packets, in the range of 0 to 10. To disable the address conflict detection, set the value to 0. Usage guidelines To avoid IP address conflicts, the DHCP server pings an IP address before assigning it to a DHCP client. If a ping attempt succeeds, the server determines that the IP address is in use and picks a new IP address. If all the ping attempts fail, the server assigns the IP address to the requesting DHCP client. Examples # Set the maximum number of ping packets to 10. <Sysname> system-view [Sysname] dhcp server ping packets 10 Related commands dhcp server ping timeout display dhcp server conflict reset dhcp server conflict dhcp server ping timeoutUse dhcp server ping timeout to set the ping response timeout time on the DHCP server. Use undo dhcp server ping timeout to restore the default. Syntax dhcp server ping timeout milliseconds undo dhcp server ping timeout Default The ping response timeout time is 500 milliseconds. Views System view Predefined user roles network-admin mdc-admin Parameters milliseconds: Specifies the timeout time in the range of 0 to 10000 milliseconds. To disable the ping operation for address conflict detection, set the value to 0 milliseconds. Usage guidelines To avoid IP address conflicts, the DHCP server pings an IP address before assigning it to a DHCP client. If a ping attempt succeeds, the server determines that the IP address is in use and picks a new IP address. If all the ping attempts fail, the server assigns the IP address to the requesting DHCP client. Examples # Set the response timeout time to 1000 milliseconds. <Sysname> system-view [Sysname] dhcp server ping timeout 1000 Related commands dhcp server ping packets display dhcp server conflict reset dhcp server conflict dhcp server relay information enableUse dhcp server relay information enable to enable the DHCP server to handle Option 82. Use undo dhcp server relay information enable to configure the DHCP server to ignore Option 82. Syntax dhcp server relay information enable undo dhcp server relay information enable Default The DHCP server handles Option 82. Views System view Predefined user roles network-admin mdc-admin Usage guidelines Upon receiving a DHCP request that contains Option 82, the server copies the original Option 82 into the response. If the server is configured to ignore Option 82, the response will not contain Option 82. Examples # Configure the DHCP server to ignore Option 82. <Sysname> system-view [Sysname] undo dhcp server relay information enable display dhcp server conflictUse display dhcp server conflict to display information about IP address conflicts. Syntax display dhcp server conflict [ ip ip-address ] [ vpn-instance vpn-instance-name ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters ip ip-address: Displays conflict information about the specified IP address. If you do not specify this option, this command displays information about all IP address conflicts. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command displays IP address conflict information for the public network. Usage guidelines The DHCP server generates IP address conflict information in the following situations: · Before assigning an IP address to a DHCP client, the DHCP server pings the IP address and discovers that another host is using the address. · The DHCP client sends a DECLINE packet to the DHCP server to inform the server of an IP address conflict. · The DHCP server discovers that the only assignable address in the address pool is its own IP address. Examples # Display information about all IP address conflicts. <Sysname> display dhcp server conflict IP address Detect time 4.4.4.1 Apr 25 16:57:20 2007 4.4.4.2 Apr 25 17:00:10 2007 Table 1 Command output
Related commands reset dhcp server conflict display dhcp server databaseUse display dhcp server database to display information about DHCP binding auto backup. Syntax display dhcp server database Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Examples # Display information about DHCP binding auto backup. <Sysname> display dhcp server database File name : database.dhcp Username : Password : Update interval : 600 seconds Latest write time : Feb 8 16:09:53 2014 Status : Last write succeeded. Table 2 Command output
display dhcp server expiredUse display dhcp server expired to display the lease expiration information. Syntax display dhcp server expired [ [ ip ip-address ][ vpn-instance vpn-instance-name ]| pool pool-name ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters ip ip-address: Displays lease expiration information about the specified IP address. If you do not specify an IP address, this command displays lease expiration information about all IP addresses. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command displays lease expiration information about IP addresses for the public network. pool pool-name: Displays lease expiration information about the specified address pool. The pool name is a case-insensitive string of 1 to 63 characters. If you do not specify an address pool, this command displays lease expiration information about all address pools. Usage guidelines DHCP assigns these expired IP addresses to DHCP clients when all available addresses have been assigned. Examples # Display all lease expiration information. <Sysname> display dhcp server expired IP address Client-identifier/Hardware address Lease expiration 4.4.4.6 3030-3066-2e65-3230-302e-3130-3234 Apr 25 17:10:47 2007 -2d45-7468-6572-6e65-7430-2f31 Table 3 Command output
Related commands reset dhcp server expired display dhcp server free-ipUse display dhcp server free-ip to display information about assignable IP addresses. Syntax display dhcp server free-ip [ pool pool-name | vpn-instance vpn-instance-name ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters pool pool-name: Displays assignable IP addresses in the specified address pool. The pool name is a case-insensitive string of 1 to 63 characters. If you do not specify an address pool, this command displays all assignable IP addresses for all address pools. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command displays assignable IP addresses in address pools for the public network. Examples # Display assignable IP addresses in all address pools. <Sysname> display dhcp server free-ip Pool name: 1 Network: 10.0.0.0 mask 255.0.0.0 IP ranges from 10.0.0.10 to 10.0.0.100 IP ranges from 10.0.0.105 to 10.0.0.255 Secondary networks: 10.1.0.0 mask 255.255.0.0 IP ranges from 10.1.0.0 to 10.1.0.255 10.2.0.0 mask 255.255.0.0 IP Ranges from 10.2.0.0 to 10.2.0.255 Pool name: 2 Network: 20.1.1.0 mask 255.255.255.0 IP ranges from 20.1.1.0 to 20.1.1.255 Table 4 Command output
Related commands address range dhcp server ip-pool network display dhcp server ip-in-useUse display dhcp server ip-in-use to display binding information about assigned IP addresses. Syntax display dhcp server ip-in-use [ [ ip ip-address ] [ vpn-instance vpn-instance-name ] | pool pool-name ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters ip ip-address: Displays binding information about the specified assigned IP address. If you do not specify an IP address, this command displays binding information about all assigned IP addresses. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command displays binding information about assigned IP addresses for the public network. pool pool-name: Displays binding information about assigned IP addresses in the specified address pool. The pool name is a case-insensitive string of 1 to 63 characters. If you do not specify an address pool, this command displays binding information about assigned IP addresses in all address pools. Usage guidelines The binding information can be used by other security modules only when the DHCP server is configured on the gateway of DHCP clients. If the lease deadline exceeds the year 2100, the lease expiration time is displayed as After 2100. Examples # Display binding information about all assigned DHCP addresses. <Sysname> display dhcp server ip-in-use IP address Client identifier/ Lease expiration Type Hardware address 10.1.1.1 4444-4444-4444 Not used Static(F) 10.1.1.2 3030-3030-2e30-3030- May 1 14:02:49 2015 Auto(C) 662e-3030-3033-2d45- 7468-6572-6e65-74 10.1.1.3 1111-1111-1111 After 2100 Static(C) Table 5 Command output
Related commands reset dhcp server ip-in-use display dhcp server poolUse display dhcp server pool to display information about a DHCP address pool. Syntax display dhcp server pool [ pool-name | vpn-instance vpn-instance-name ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters pool-name: Displays information about the specified address pool. The pool name is a case-insensitive string of 1 to 63 characters. If you do not specify the pool-name argument, this command displays information about all address pools. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command displays information about address pools for the public network. Examples # Display information about all DHCP address pools. <Sysname> display dhcp server pool Pool name: 0 Network 20.1.1.0 mask 255.255.255.0 class a range 20.1.1.50 20.1.1.60 bootfile-name abc.cfg dns-list 20.1.1.66 20.1.1.67 20.1.1.68 domain-name www.aabbcc.com bims-server ip 192.168.0.51 sharekey cipher $c$3$K13OmQPi791YvQoF2Gs1E+65LOU= option 2 ip-address 1.1.1.1 expired 1 2 3 0 Pool name: 1 Network 20.1.1.0 mask 255.255.255.0 secondary networks: 20.1.2.0 mask 255.255.255.0 20.1.3.0 mask 255.255.255.0 bims-server ip 192.168.0.51 port 50 sharekey cipher $c$3$K13OmQPi791YvQoF2Gs1E+65LOU= forbidden-ip 20.1.1.22 20.1.1.36 20.1.1.37 forbidden-ip 20.1.1.22 20.1.1.23 20.1.1.24 gateway-list 1.1.1.1 2.2.2.2 4.4.4.4 nbns-list 5.5.5.5 6.6.6.6 7.7.7.7 netbios-type m-node option 2 ip-address 1.1.1.1 expired 1 0 0 0 Pool name: 2 Network 20.1.1.0 mask 255.255.255.0 address range 20.1.1.1 to 20.1.1.15 class departmentA range 20.1.1.20 to 20.1.1.29 class departmentB range 20.1.1.30 to 20.1.1.40 next-server 20.1.1.33 tftp-server domain-name www.dian.org.cn tftp-server ip-address 192.168.0.120 voice-config ncp-ip 10.1.1.2 voice-config as-ip 10.1.1.5 voice-config voice-vlan 3 enable voice-config fail-over 10.1.1.1 123* option 2 ip-address 1.1.1.3 expired 1 0 0 0 Pool name: 3 static bindings: ip-address 10.10.1.2 mask 255.0.0.0 hardware-address 00e0-00fc-0001 ethernet ip-address 10.10.1.3 mask 255.0.0.0 client-identifier aaaa-bbbb expired unlimited Table 6 Command output
display dhcp server statisticsUse display dhcp server statistics to display the DHCP server statistics. Syntax display dhcp server statistics [ pool pool-name | vpn-instance vpn-instance-name ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters pool pool-name: Specifies an address pool by its name, a case-insensitive string of 1 to 63 characters. If you do not specify this option, this command displays information about all address pools. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command displays DHCP server statistics for the public network. Examples # Display the DHCP server statistics. <Sysname> display dhcp server statistics Pool number: 1 Pool utilization: 0.39% Bindings: Automatic: 1 Manual: 0 Expired: 0 Conflict: 1 Messages received: 10 DHCPDISCOVER: 5 DHCPREQUEST: 3 DHCPDECLINE: 0 DHCPRELEASE: 2 DHCPINFORM: 0 BOOTPREQUEST: 0 Messages sent: 6 DHCPOFFER: 3 DHCPACK: 3 DHCPNAK: 0 BOOTPREPLY: 0 Bad Messages: 0 Table 7 Command output
Related commands reset dhcp server statistics dns-listUse dns-list to specify DNS server addresses in a DHCP address pool. Use undo dns-list to remove DNS server addresses from a DHCP address pool. Syntax dns-list ip-address&<1-8> undo dns-list [ ip-address&<1-8> ] Default No DNS server address is specified. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip-address&<1-8>: Specifies a space-separated list of up to eight DNS servers. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. If you do not specify any parameters, the undo dns-list command deletes all DNS server addresses in the DHCP address pool. Examples # Specify DNS server address 10.1.1.254 in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] dns-list 10.1.1.254 Related commands display dhcp server pool domain-nameUse domain-name to specify a domain name in a DHCP address pool. Use undo domain-name to restore the default. Syntax domain-name domain-name undo domain-name Default No domain name is specified. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters domain-name: Specifies the domain name, a case-sensitive string of 1 to 50 characters. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify domain name company.com in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] domain-name company.com Related commands display dhcp server pool expiredUse expired to set the lease duration in a DHCP address pool. Use undo expired to restore the default lease duration for a DHCP address pool. Syntax expired { day day [ hour hour [ minute minute [ second second ] ] ] | unlimited } undo expired Default The lease duration of a dynamic DHCP address pool is one day. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters day day: Specifies the number of days, in the range of 0 to 365. hour hour: Specifies the number of hours, in the range of 0 to 23. The default is 0. minute minute: Specifies the number of minutes, in the range of 0 to 59. The default is 0. second second: Specifies the number of seconds, in the range of 0 to 59. The default is 0. unlimited: Specifies the unlimited lease duration, which is actually 136 years. Usage guidelines The DHCP server assigns an IP address together with the lease duration to the DHCP client. Before the lease expires, the DHCP client must extend the lease duration. · If the lease extension operation succeeds, the DHCP client can continue to use the IP address. · If the lease extension operation does not succeed, both of the following events occur: ¡ The DHCP client cannot use the IP address after the lease duration expires. ¡ The DHCP server will label the IP address as an expired address. Examples # Set the lease duration to 1 day, 2 hours, 3 minutes, and 4 seconds in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] expired day 1 hour 2 minute 3 second 4 Related commands display dhcp server expired display dhcp server pool reset dhcp server expired forbidden-ipUse forbidden-ip to exclude IP addresses from dynamic allocation in an address pool. Use undo forbidden-ip to remove the configuration. Syntax forbidden-ip ip-address&<1-8> undo forbidden-ip [ ip-address&<1-8> ] Default No IP addresses are excluded from dynamic allocation in an address pool. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip-address&<1-8>: Specifies a space-separated list of up to eight excluded IP addresses. Usage guidelines The excluded IP addresses in an address pool are still assignable in other address pools. You can exclude a maximum of 4096 IP addresses in an address pool by executing this command multiple times. If you do not specify any parameters, the undo forbidden-ip command removes all excluded IP addresses. Examples # Exclude IP addresses 192.168.1.3 and 192.168.1.10 from dynamic allocation in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] forbidden-ip 192.168.1.3 192.168.1.10 Related commands dhcp server forbidden-ip display dhcp server pool gateway-listUse gateway-list to specify gateway addresses in a DHCP address pool or a DHCP secondary subnet. Use undo gateway-list to remove the specified gateway addresses from a DHCP address pool or a DHCP secondary subnet. Syntax gateway-list ip-address&<1-64> [ export-route ] undo gateway-list [ ip-address&<1-64> ] [ export-route ] Default No gateway address is configured in a DHCP address pool or a DHCP secondary subnet. Views DHCP address pool view DHCP secondary subnet view Predefined user roles network-admin mdc-admin Parameters ip-address&<1-64>: Specifies a space-separated list of up to 64 gateway addresses. Gateway addresses must reside on the same subnet as the assignable IP addresses. export-route: Binds the gateways to the device's MAC address in the address management module. The ARP module will use the entries to reply to ARP requests from the DHCP clients. If you do not specify this keyword, the gateways will not be bound to the device's MAC address. Usage guidelines The DHCP server assigns gateway addresses to clients on a secondary subnet in the following ways: · If gateways are specified in both address pool view and secondary subnet view, DHCP assigns those specified in the secondary subnet view. · If gateways are specified in address pool view but not in secondary subnet view, DHCP assigns those specified in address pool view. If you do not specify any parameters, the undo gateway-list command deletes all gateway addresses. Examples # Specify gateway address 10.1.1.1 in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] gateway-list 10.1.1.1 Related commands display dhcp server pool if-matchUse if-match to configure a match rule for a DHCP user class. Use undo if-match to delete a match rule for a DHCP user class. Syntax if-match rule rule-number { hardware-address hardware-address mask hardware-address-mask | option option-code [ ascii ascii-string [ offset offset | partial ] | hex hex-string [ mask mask | offset offset length length | partial ] ] | relay-agent gateway-address } undo if-match rule rule-number Default No match rules are configured for the DHCP user class. Views DHCP user class view Predefined user roles network-admin mdc-admin Parameters rule rule-number: Assigns the match rule an ID in the range of 1 to 16. A smaller ID represents a higher match priority. hardware-address hardware-address: Specifies a hardware address, a string of 4 to 39 characters. The string contains hyphen-separated hexadecimal numbers. The last hexadecimal number can be a two-digit or four-digit number, and the other hexadecimal numbers must be four-digit numbers. For example, aabb-ccdd-ee is valid, and aabb-c-dddd or aabb-cc-dddd is invalid. mask hardware-address-mask: Specifies the mask to be ANDed with the specified hardware address for the match operation. The length of the maskmust be the same as that of the hardware address. option option-code: Specifies a DHCP option by its number in the range of 1 to 254. ascii ascii-string: Specifies an ASCII string of 1 to 128 characters. offset offset: Specifies the offset in bytes after which the match operation starts. The value range is 0 to 254. If you specify an ASCII string, a packet matches the rule if the option content after the offset is the same as the ASCII string. If you specify a hexadecimal number, a packet matches the rule if the option content of the specified length after the offset is the same as the hexadecimal number. partial: Enables partial match. A packet matches a rule if the specified option in the packet contains the ASCII string or hexadecimal number specified in the rule. For example, if you specify abc in the rule, option content xabc, xyzabca, xabcyz, and abcxyz all match the rule. hex hex-string: Specifies a hexadecimal number. The length of the hexadecimal number must be an even number in the range of 2 to 256. mask mask: Specifies a hexadecimal mask for the match operation. The mask length must be an even number in the range of 2 to 256 and be the same as the hex-string length. The DHCP server selects option content of the mask length from the start and ANDs the selected option content and the specified hexadecimal number with the mask. The packet matches the rule if the two AND operation results are the same. length length: Specifies the length of the option content to be matched, in the range of 1 to 128 bytes. The length must be the same as the hex-string length. relay-agent gateway-address: Specifies a giaddr field value. The value is an IPv4 address in the dotted decimal notation. A packet matches the rule if its giaddr field value is the same as that in the rule. Usage guidelines If a DHCP request sent by a DHCP client matches a rule in a DHCP user class, the DHCP client matches the user class. You can configure multiple match rules for a DHCP user class. Each match rule is uniquely identified by a rule ID within its type (hardware address, option, or relay agent address). · If the rule that you are configuring has the same ID and type as an existing rule, the new rule overwrites the existing rule. · If the rule that you are configuring has the same ID as an existing rule but a different type, the new rule takes effect and coexists with the existing rule. As a best practice, do not assign the same ID to rules of different types. · Rules of different IDs cannot have the same rule content. When you configure an if-match hardware-address rule, follow these guidelines: · The hardware address type supports only the MAC address. A rule does not match clients with hardware addresses of other types. · The specified hardware address must be of the same length as the client hardware addresses to be matched. To match MAC addresses, the specified hardware address must be six bytes long. · The fs and 0s in the mask for the hardware match operation can be noncontiguous. For example, the rule if-match rule 1 hardware-address 0094-0000-1100 mask ffff-0000-ff00 matches hardware addresses in which the first two bytes are 0094 and the fifth byte is 11. When you configure an if-match option rule, follow these guidelines: · To match packets that contain an option, specify only the option-code argument. · To match a hexadecimal number by AND operations, specify the option option-code hex hex-string mask mask options. · To match a hexadecimal number directly, specify the option option-code hex hex-string [ offset offset length length | partial ] options. If you do not specify the offset, length, or partial parameter, a packet matches a rule if the option content starts with the hexadecimal number. · To match an ASCII string, specify the option option-code ascii ascii-string [ offset offset | partial ] options. If you do not specify the offset or partial parameter, a packet matches a rule if the option content starts with the ASCII string. Examples # Configure match rule 1 for DHCP user class exam to match DHCP requests in which the hardware address is six bytes long and begins with 0094. <Sysname> system-view [Sysname] dhcp class exam [Sysname-dhcp-class-exam] if-match rule 1 hardware-address 0094-0000-0101 mask ffff-0000-0000 # Configure match rule 2 for DHCP user class exam to match DHCP requests that contain Option 82. <Sysname> system-view [Sysname] dhcp class exam [Sysname-dhcp-class-exam] if-match rule 2 option 82 # Configure match rule 3 for DHCP user class exam. The rule matches DHCP requests in which the highest bit of the fourth byte in Option 82 is the hexadecimal number 1. <Sysname> system-view [Sysname] dhcp class exam [Sysname-dhcp-class-exam] if-match rule 3 option 82 hex 00000080 mask 00000080 # Configure match rule 4 for DHCP user class exam. The rule matches DHCP requests in which the first three bytes of Option 82 are the hexadecimal number 13ae92. <Sysname> system-view [Sysname] dhcp class exam [Sysname-dhcp-class-exam] if-match rule 4 option 82 hex 13ae92 offset 0 length 3 # Configure match rule 5 for DHCP user class exam. The rule matches DHCP requests in which the Option 82 contains the hexadecimal number 13ae. <Sysname> system-view [Sysname] dhcp class exam [Sysname-dhcp-class-exam] if-match rule 5 option 82 hex 13ae partial # Configure match rule 6 for DHCP user class exam to match DHCP requests in which the giaddr field is 10.1.1.1. <Sysname> system-view [Sysname] dhcp class exam [Sysname-dhcp-class-exam] if-match rule 6 relay-agent 10.1.1.1 Related commands dhcp class ip-in-use thresholdUse ip-in-use threshold to set a threshold for the address pool usage alarming. Use undo ip-in-use threshold to restore the default. Syntax ip-in-use threshold threshold-value undo ip-in-use threshold Default The address pool usage threshold is 100%. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters threshold-value: Specifies the threshold for the address pool usage percentage. The value range is 1 to 100. Usage guidelines If you execute this command in the same address pool view multiple times, the most recent configuration takes effect. When the address pool usage exceeds the threshold, the system sends log messages to the information center. According to the log information, you can optimize the address pool configuration. For more information about the information center, see Network Management and Monitoring Configuration Guide. Examples # Set the address pool usage threshold to 85%. <Sysname> system-view [Sysname] dhcp server ip-pool p1 [Sysname-dhcp-pool-p1] ip-in-use threshold 85 nbns-listUse nbns-list to specify WINS server addresses in a DHCP address pool. Use undo nbns-list to remove the specified WINS server addresses. Syntax nbns-list ip-address&<1-8> undo nbns-list [ ip-address&<1-8> ] Default No WINS server address is specified. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip-address&<1-8>: Specifies a space-separated list of up to eight WINS server IP addresses. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. If you do not specify any parameters, the undo nbns-list command deletes all WINS server addresses. Examples # Specify WINS server address 10.1.1.1 in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] nbns-list 10.1.1.1 Related commands display dhcp server pool netbios-type netbios-typeUse netbios-type to specify the NetBIOS node type in a DHCP address pool. Use undo netbios-type to restore the default. Syntax netbios-type { b-node | h-node | m-node | p-node } undo netbios-type Default No NetBIOS node type is specified. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters b-node: Specifies the broadcast node. A b-node client sends the destination name in a broadcast message to get the name-to-IP mapping from a server. h-node: Specifies the hybrid node. An h-node client unicasts the destination name to a WINS server. If it does not receive a response, the h-node client broadcasts the destination name to get the mapping from a server. m-node: Specifies the mixed node. An m-node client broadcasts the destination name. If it does not receive a response, the m-node client unicasts the destination name to the WINS server to get the mapping. p-node: Specifies the peer-to-peer node. A p-node client sends the destination name in a unicast message to get the mapping from the WINS server. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify the NetBIOS node type as p-node in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] netbios-type p-node Related commands display dhcp server pool nbns-list networkUse network to specify the subnet for dynamic allocation in a DHCP address pool. Use undo network to remove the specified subnet. Syntax network network-address [ mask-length | mask mask ] [ export-route ] [ secondary ] undo network network-address [ mask-length | mask mask ] [ secondary ] Default No subnet is specified in a DHCP address pool. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters network-address: Specifies the subnet for dynamic allocation. If no mask length or mask is specified, the natural mask will be used. mask-length: Specifies the mask length in the range of 1 to 30. mask mask: Specifies the mask in dotted decimal format. export-route: Advertises the subnet assigned to DHCP clients. If you do not specify this keyword, the subnet will not be advertised. secondary: Specifies the subnet as a secondary subnet. If you do not specify this keyword, this command specifies the primary subnet. If the addresses in the primary subnet are used up, the DHCP server can select addresses from a secondary subnet for clients. Usage guidelines You can use the secondary keyword to specify a secondary subnet and enter its view. In secondary subnet view, you can specify gateways by using the gateway-list command for DHCP clients in the secondary subnet. You can specify only one primary subnet for a DHCP address pool. If you execute the network command multiple times, the most recent configuration takes effect. You can specify up to 32 secondary subnets for a DHCP address pool. The primary subnet and secondary subnets in a DHCP address pool must not have the same network address and mask. If you have used the address range or class command in an address pool, you cannot specify a secondary subnet in the same address pool. Modifying or removing the network configuration deletes the assigned addresses from the current address pool. If you execute the network export-route command multiple times, the most recent configuration takes effect. Examples # Specify primary subnet 192.168.8.0/24 and secondary subnet 192.168.10.0/24 in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] network 192.168.8.0 mask 255.255.255.0 [Sysname-dhcp-pool-0] network 192.168.10.0 mask 255.255.255.0 secondary [Sysname-dhcp-pool-0-secondary] Related commands display dhcp server pool gateway-list next-serverUse next-server to specify the IP address of a server in a DHCP address pool. Use undo next-server to restore the default. Syntax next-server ip-address undo next-server Default No server's IP address is specified in a DHCP address pool. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip-address: Specifies the IP address of a server. Usage guidelines Upon startup, the DHCP client obtains an IP address and the specified server IP address. Then it contacts the specified server, such as a TFTP server, to get other boot information. If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify a server's IP address 10.1.1.254 in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] next-server 10.1.1.254 Related commands display dhcp server pool optionUse option to customize a DHCP option. Use undo option to remove a customized DHCP option. Syntax option code { ascii ascii-string | hex hex-string | ip-address ip-address&<1-8> } undo option code Default No DHCP option is customized. Views DHCP address pool view DHCP option group view Predefined user roles network-admin mdc-admin Parameters code: Specifies the number of the customized option, in the range of 2 to 254, excluding 50 through 54, 56, 58, 59, 61, and 82. ascii ascii-string: Specifies a case-sensitive ASCII string of 1 to 255 characters as the option content. hex hex-string: Specifies a hexadecimal number as the option content. The length of the hexadecimal number must be an even number in the range of 2 to 256. ip-address ip-address&<1-8>: Specifies a space-separated list of up to eight IP addresses as the option content. Usage guidelines The DHCP server fills the customized option with the specified ASCII string, hexadecimal number, or IP addresses, and sends it in a response to the client. You can customize options for the following purposes: · Add newly released options. · Add options for which the vendor defines the contents, for example, Option 43. · Add options for which the CLI does not provide a dedicated configuration command. For example, you can use the option 4 ip-address 1.1.1.1 command to define the time server address1.1.1.1 for DHCP clients. · Add all option values if the actual requirement exceeds the limit for a dedicated option configuration command. For example, the dns-list command can specify up to eight DNS servers. To specify more than eight DNS server, you must use the option 6 command to define all DNS servers. DHCP options specified by dedicated commands take precedence over those specified by the option commands. For example, if a DNS server address is specified by both the dns-list command and the option 6 command, the server uses the address specified by the dns-list command. DHCP options specified in DHCP option groups take precedence over those specified in DHCP address pools. If you execute this command multiple times with the same code specified, the most recent configuration takes effect. Examples # Configure Option 7 to specify log server address 2.2.2.2 in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] option 7 ip-address 2.2.2.2 Related commands display dhcp server pool reset dhcp server conflictUse reset dhcp server conflict to clear IP address conflict information. Syntax reset dhcp server conflict [ ip ip-address ] [ vpn-instance vpn-instance-name ] Views User view Predefined user roles network-admin mdc-admin Parameters ip ip-address: Clears conflict information about the specified IP address. If you do not specify this option, this command clears all address conflict information. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command clears conflict information about IP addresses for the public network. Usage guidelines Address conflicts occur when dynamically assigned IP addresses have been statically configured for other hosts. After you modify the address pool configuration, the conflicted addresses might become assignable. To assign these addresses, use the reset dhcp server conflict command to clear the conflict information first. Examples # Clear all IP address conflict information. <Sysname> reset dhcp server conflict Related commands display dhcp server conflict reset dhcp server expiredUse reset dhcp server expired to clearbinding information about expired IP addresses. Syntax reset dhcp server expired [ [ ip ip-address ] [vpn-instance vpn-instance-name ]| pool pool-name ] Views User view Predefined user roles network-admin mdc-admin Parameters ip ip-address: Clears binding information about the specified expired IP address. If you do not specify an IP address, this command clears binding information about all expired IP addresses. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command clears lease expiration information about IP addresses for the public network. pool pool-name: Clears binding information about the expired IP addresses in the specified address pool. The pool name is a case-insensitive string of 1 to 63 characters. If you do not specify an address pool, this command clears binding information about expired IP addresses in all address pools. Examples # Clear binding information about all expired IP addresses. <Sysname> reset dhcp server expired Related commands display dhcp server expired reset dhcp server ip-in-useUse reset dhcp server ip-in-use to clear binding information about assigned IP addresses. Syntax reset dhcp server ip-in-use [ [ ip ip-address ] [ vpn-instance vpn-instance-name ] | pool pool-name ] Views User view Predefined user roles network-admin mdc-admin Parameters ip ip-address: Clears binding information about the specified assigned IP address. If you do not specify an IP address, this command clears binding information about all assigned IP addresses. vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command clears binding information for the public network. pool pool-name: Clears binding information about assigned IP addresses in the specified address pool. The pool name is a case-insensitive string of 1 to 63 characters. If you do not specify an address pool, this command clears binding information about assigned IP addresses in all address pools. Usage guidelines If you use this command to clear information about an assigned static binding, the static binding becomes a free static binding. Examples # Clear binding information about IP address 10.110.1.1. <Sysname> reset dhcp server ip-in-use ip 10.110.1.1 Related commands display dhcp server ip-in-use reset dhcp server statisticsUse reset dhcp server statistics to clear DHCP server statistics. Syntax reset dhcp server statistics [ vpn-instance vpn-instance-name ] Views User view Predefined user roles network-admin mdc-admin Parameters vpn-instance vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command clears DHCP server statistics for the public network. Examples # Clear DHCP server statistics. <Sysname> reset dhcp server statistics Related commands display dhcp server statistics static-bindUse static-bind to statically bind a client ID or MAC address to an IP address. Use undo static-bind to remove a static binding. Syntax static-bind ip-address ip-address [ mask-length | mask mask ] { client-identifier client-identifier | hardware-address hardware-address [ ethernet | token-ring ] } undo static-bind ip-address ip-address Default No static binding is specified in a DHCP address pool. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip-address ip-address: Specifies the IP address of the static binding. The natural mask is used if no mask length or mask is specified. mask-length: Specifies the mask length in the range of 1 to 30. mask mask: Specifies the mask, in dotted decimal format. client-identifier client-identifier: Specifies the client ID of the static binding, a string of 4 to 254 characters. The string can contain only hexadecimal numbers and hyphen (-), in the format of H-H-H…. The last H can be a two-digit or four-digit hexadecimal number while the other Hs must be all four-digit hexadecimal numbers. For example, aabb-cccc-dd is correct, and aabb-c-dddd and aabb-cc-dddd are not correct. hardware-address hardware-address: Specifies the client hardware address of the static binding, a string of 4 to 39 characters. The string can contain only hexadecimal numbers and hyphen (-), in the format of H-H-H…. The last H can be a two-digit or four-digit hexadecimal number while the other Hs must be all four-digit hexadecimal numbers. For example, aabb-cccc-dd is correct, and aabb-c-dddd and aabb-cc-dddd are not correct. ethernet: Specifies the client hardware address type as Ethernet. The default type is Ethernet. token-ring: Specifies the client hardware address type as token ring. Usage guidelines The IP address of a static binding must not be an interface address of the DHCP server. Otherwise, an IP address conflict occurs, and the bound client cannot obtain the IP address. You can specify multiple static bindings in an address pool. The total number of static bindings in all address pools cannot exceed 8192. An IP address can be bound to only one DHCP client. To modify the binding for a DHCP client, first execute the undo form of the command to delete the existing binding and then create a new binding. Examples # Bind IP address 10.1.1.1/24 to client ID 00aa-aabb in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] static-bind ip-address 10.1.1.1 mask 255.255.255.0 client-identifier 00aa-aabb Related commands display dhcp server pool tftp-server domain-nameUse tftp-server domain-name to specify a TFTP server name in a DHCP address pool. Use undo tftp-server domain-name to restore the default. Syntax tftp-server domain-name domain-name undo tftp-server domain-name Default No TFTP server name is specified. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters domain-name: Specifies the TFTP server name, a case-sensitive string of 1 to 63 characters. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify TFTP server name aaa in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] tftp-server domain-name aaa Related commands display dhcp server pool tftp-server ip-address tftp-server ip-addressUse tftp-server ip-address to specify a TFTP server address in a DHCP address pool. Use undo tftp-server ip-address to restore the default. Syntax tftp-server ip-address ip-address undo tftp-server ip-address Default No TFTP server address is specified. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip-address: Specifies the IP address of a TFTP server. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify TFTP server address 10.1.1.1 in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] tftp-server ip-address 10.1.1.1 Related commands display dhcp server pool tftp-server domain-name valid classUse valid class to add DHCP user classes to the whitelist. Use undo valid class to remove DHCP user classes from the whitelist. Syntax valid class class-name&<1-8> undo valid class class-name&<1-8> Default No DHCP user class is listed on the whitelist. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters class-name&<1-8>: Specifies a space-separated list of up to eight DHCP user classes by their names, a case-insensitive string of 1 to 63 characters. Usage guidelines For this command to take effect, you must enable the DHCP user class whitelist. Examples # Add DHCP user classes test1 and test2 to the whitelist in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] valid class test1 test2 Related commands dhcp class verify class verify classUse verify class to enable the DHCP user class whitelist. Use undo verify class to disable the DHCP user class whitelist. Syntax verify class undo verify class Default The DHCP user class whitelist is disabled. Views DHCP address pool view Predefined user roles network-admin mdc-admin Usage guidelines After you enable the DHCP user class whitelist, the DHCP server processes requests only from clients on the DHCP user class whitelist. The DHCP user class whitelist does not take effect on clients that request static IP addresses, and the server always processes their requests. Examples # Enable the DHCP user class whitelist in DHCP address pool 0. [Sysname] system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] verify class Related commands valid class voice-configUse voice-config to configure the content for Option 184 in a DHCP address pool. Use undo voice-config to remove the Option 184 content from a DHCP address pool. Syntax voice-config { as-ip ip-address | fail-over ip-address dialer-string | ncp-ip ip-address | voice-vlan vlan-id { disable | enable } } undo voice-config [ as-ip | fail-over | ncp-ip | voice-vlan ] Default No Option 184 content is configured in a DHCP address pool. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters as-ip ip-address: Specifies the IP address of the backup network calling processor. fail-over ip-address dialer-string: Specifies the failover IP address and dialer string. The dialer-string is a string of 1 to 39 characters. Valid characters are digits and asterisk (*). ncp-ip ip-address: Specifies the IP address of the primary network calling processor. voice-vlan vlan-id: Specifies the voice VLAN ID in the range of 2 to 4094. · disable: Disables the specified VLAN. DHCP clients will not take this VLAN as their voice VLAN. · enable: Enables the specified VLAN. DHCP clients will take this VLAN as their voice VLAN. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Configure Option 184 in DHCP address pool 0. The primary and backup network calling processors are at 10.1.1.1 and 10.2.2.2, respectively. The voice VLAN 3 is enabled. The failover IP address is 10.3.3.3. The dialer string is 99*. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] voice-config ncp-ip 10.1.1.1 [Sysname-dhcp-pool-0] voice-config as-ip 10.2.2.2 [Sysname-dhcp-pool-0] voice-config voice-vlan 3 enable [Sysname-dhcp-pool-0] voice-config fail-over 10.3.3.3 99* Related commands display dhcp server pool vpn-instanceUse vpn-instance to apply a DHCP address pool to a VPN instance. Use undo vpn-instance to restore the default. Syntax vpn-instance vpn-instance-name undo vpn-instance Default The DHCP address pool is not applied to any VPN instance. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters vpn-instance-name: Specifies an MPLS L3VPN instance by its name, a case-sensitive string of 1 to 31 characters. Usage guidelines If a DHCP address pool is applied to a VPN instance, the DHCP server assigns IP addresses in this address pool to clients in the specified VPN instance. The DHCP server identifies the VPN instance to which a DHCP client belongs according to the following information: · The client's VPN information stored in authentication modules. · The VPN information of the DHCP server's interface that receives DHCP packets from the client. The VPN information from authentication modules takes priority over the VPN information of the receiving interface. Examples # Apply DHCP address pool 0 to VPN instance abc. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] vpn-instance abc DHCP relay agent commandsdhcp relay check mac-addressUse dhcp relay check mac-address to enable MAC address check on the relay agent. Use undo dhcp relay check mac-address to disable MAC address check on the relay agent. Syntax dhcp relay check mac-address undo dhcp relay check mac-address Default The MAC address check feature is disabled. Views Interface view Predefined user roles network-admin mdc-admin Usage guidelines This feature enables the DHCP relay agent to compare the chaddr field of a received DHCP request with the source MAC address in the frame header. If they are the same, the DHCP relay agent forwards the request to the DHCP server. If they are not the same, the DHCP relay agent discards the request. The MAC address check feature takes effect only when the dhcp select relay command has already been configured on the interface. Enable the MAC address check feature only on the DHCP relay agent directly connected to the DHCP clients. A DHCP relay agent changes the source MAC address of DHCP packets before sending them. Examples # Enable MAC address check on the DHCP relay agent. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp relay check mac-address Related commands dhcp select relay dhcp relay check mac-address aging-timeUse dhcp relay check mac-address aging-time to set the aging time for MAC address check entries on the DHCP relay agent. Use undo dhcp relay check mac-address aging-time to restore the default. Syntax dhcp relay check mac-address aging-time time undo dhcp relay check mac-address aging-time Default The aging time is 30 seconds. Views System view Predefined user roles network-admin mdc-admin Parameters time: Specifies the aging time for MAC address check entries, in the range of 30 to 600 seconds. Usage guidelines This command takes effect only after you execute the dhcp relay check mac-address command. Examples # Set the aging time to 60 seconds for MAC address check entries on the DHCP relay agent. <Sysname> system-view [Sysname] dhcp relay check mac-address aging-time 60 dhcp relay client-information recordUse dhcp relay client-information record to enable recording client information in relay entries. Use undo dhcp relay client-information record to disable the feature. Syntax dhcp relay client-information record undo dhcp relay client-information record Default The DHCP relay agent does not record client information in relay entries. Views System view Predefined user roles network-admin mdc-admin Usage guidelines Client information is recorded only when the DHCP relay agent is configured on the gateway of DHCP clients. A relay entry contains information about a client such as the client's IP and MAC addresses. Disabling the recording of client information deletes all recorded relay entries. Examples # Enable the recording of relay entries on the relay agent. <Sysname> system-view [Sysname] dhcp relay client-information record Related commands dhcp relay client-information refresh dhcp relay client-information refresh enable dhcp relay client-information refreshUse dhcp relay client-information refresh to set the interval at which the DHCP relay agent refreshes relay entries. Use undo dhcp relay client-information refresh to restore the default. Syntax dhcp relay client-information refresh [ auto | interval interval ] undo dhcp relay client-information refresh Default The refresh interval is automatically calculated based on the number of relay entries. Views System view Predefined user roles network-admin mdc-admin Parameters auto: Automatically calculates the refresh interval. The more the entries, the shorter the refresh interval. The shortest interval is 50 ms. interval interval: Specifies the refresh interval in the range of 1 to 120 seconds. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Set the refresh interval to 100 seconds. <Sysname> system-view [Sysname] dhcp relay client-information refresh interval 100 Related commands dhcp relay client-information record dhcp relay client-information refresh enable dhcp relay client-information refresh enableUse dhcp relay client-information refresh enable to enable the DHCP relay agent to periodically refresh dynamic relay entries. Use undo dhcp relay client-information refresh enable to disable the DHCP relay agent to periodically refresh dynamic relay entries. Syntax dhcp relay client-information refresh enable undo dhcp relay client-information refresh enable Default The DHCP relay agent periodically refreshes relay entries. Views System view Predefined user roles network-admin mdc-admin Usage guidelines A DHCP client unicasts a DHCP-RELEASE message to the DHCP server to release its IP address. The DHCP relay agent conveys the message to the DHCP server and does not remove the IP-to-MAC entry of the client. With this feature, the DHCP relay agent uses a client's IP address and the relay interface's MAC address to periodically send a DHCP-REQUEST message to the DHCP server. · If the server returns a DHCP-ACK message or does not return any message within an interval, the DHCP relay agent performs the following operations: ¡ Removes the relay entry. ¡ Sends a DHCP-RELEASE message to the DHCP server to release the IP address. · If the server returns a DHCP-NAK message, the relay agent keeps the entry. With this feature disabled, the DHCP relay agent does not remove relay entries automatically. After a DHCP client releases its IP address, you must use the reset dhcp relay client-information on the relay agent to remove the corresponding relay entry. Examples # Disable periodic refresh of relay entries. <Sysname> system-view [Sysname] undo dhcp relay client-information refresh enable Related commands dhcp relay client-information record dhcp relay client-information refresh reset dhcp relay client-information dhcp relay dhcp-server timeoutUse dhcp relay dhcp-server timeout to set the DHCP server response timeout time for DHCP server switchover. Use undo dhcp relay dhcp-server timeout to restore the default. Syntax dhcp relay dhcp-server timeout time undo dhcp relay dhcp-server timeout Default The DHCP server response timeout time is 30 seconds. Views Interface view Predefined user roles network-admin mdc-admin Parameters time: Specifies the DHCP server response timeout time in the range of 30 to 65535 seconds. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Set the DHCP server response timeout time to 60 seconds for DHCP server switchover on VLAN-interface 2. <Sysname> system-view [Sysname] interface vlan-interface 2 [Sysname-Vlan-interface2] dhcp relay dhcp-server timeout 60 Related commands dhcp relay server-address algorithm dhcp relay gatewayUse dhcp relay gateway to specify the DHCP relay agent address to be inserted in DHCP requests. Use undo dhcp relay gateway to restore the default. Syntax dhcp relay gateway ip-address undo dhcp relay gateway Default The primary IP address of the interface is inserted in DHCP requests as the DHCP relay agent address. Views Interface view Predefined user roles network-admin mdc-admin Parameters ip-address: Specifies the DHCP relay agent address. It must be an IP address of the interface. Usage guidelines The DHCP relay agent uses the specified IP address instead of the primary IP address of the relay interface as the DHCP relay agent address. If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify 10.1.1.1 as the DHCP relay agent address to be inserted in DHCP requests on VLAN-interface 2. <Sysname> system-view [Sysname] interface vlan-interface 2 [Sysname-Vlan-interface2] dhcp relay gateway 10.1.1.1 Related commands gateway-list dhcp relay information circuit-idUse dhcp relay information circuit-id to configure the padding mode and padding format for the Circuit ID sub-option of Option 82. Use undo dhcp relay information circuit-id to restore the default. Syntax dhcp relay information circuit-id { bas | string circuit-id | vxlan-port | { normal | verbose [ node-identifier { mac | sysname | user-defined node-identifier } ] [ interface ] } [ format { ascii | hex } ] } undo dhcp relay information circuit-id Default The padding mode is normal and the padding format is hex. Views Interface view Predefined user roles network-admin mdc-admin Parameters bas: Specifies the bas mode for padding the Circuit ID sub-option. string circuit-id: Specifies the string mode that uses a case-sensitive string of 3 to 63 characters as the content of the Circuit ID sub-option. vxlan-port: Specifies the mode that uses the VXLAN ID and port number to pad the Circuit ID sub-option. normal: Specifies the normal mode, in which the padding content consists of the VLAN ID and port number. verbose: Specifies the verbose mode. The padding content includes the node identifier, interface information, and VLAN ID. The default node identifier is the MAC address of the access node. The default interface information consists of the Ethernet type (fixed to eth), chassis number, slot number, sub-slot number, and interface number. node-identifier { mac | sysname | user-defined node-identifier }: Specifies the access node identifier. · mac: Uses the MAC address of the access node as the node identifier. · sysname: Uses the device name as the node identifier. You can set the device name by using the sysname command in system view. The padding format for the device name is always ASCII regardless of the specified padding format.
· user-defined node-identifier: Uses a case-sensitive string of 1 to 50 characters as the node identifier. The padding format for the specified character string is always ASCII regardless of the specified padding format. interface: Uses the interface name as the interface information. The padding format for the interface name is always ASCII regardless of the specified padding format. format: Specifies the padding format for the Circuit ID sub-option. ascii: Specifies the ASCII padding format. hex: Specifies the hex padding format. Usage guidelines The Circuit ID sub-option cannot carry information about interface splitting or subinterfaces. For more information about interface splitting and subinterfaces, see Interface Configuration Guide. If you execute this command multiple times, the most recent configuration takes effect. The padding format for the string mode, the normal mode, or the verbose mode varies by command configuration. Table 8 shows how the padding format is determined for different modes. Table 8 Padding format for different modes
Examples # Specify the content mode as verbose, node identifier as the device name, and the padding format as ASCII for the Circuit ID sub-option. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp relay information enable [Sysname-Vlan-interface10] dhcp relay information strategy replace [Sysname-Vlan-interface10] dhcp relay information circuit-id verbose node-identifier sysname format ascii Related commands dhcp relay information enable dhcp relay information strategy display dhcp relay information dhcp relay information enableUse dhcp relay information enable to enable the DHCP relay agent to support Option 82. Use undo dhcp relay information enable to disable Option 82 support. Syntax dhcp relay information enable undo dhcp relay information enable Default The DHCP relay agent does not support Option 82. Views Interface view Predefined user roles network-admin mdc-admin Usage guidelines This command enables the DHCP relay agent to add Option 82 to DHCP requests that do not contain Option 82 before forwarding the requests to the DHCP server. The content of Option 82 is determined by the dhcp relay information circuit-id and dhcp relay information remote-id commands. If the DHCP requests contain Option 82, the relay agent handles the requests according to the strategy configured with the dhcp relay information strategy command. If this feature is disabled, the relay agent forwards requests that contain or do not contain Option 82 to the DHCP server. Examples # Enable Option 82 support on the relay agent. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp relay information enable Related commands dhcp relay information circuit-id dhcp relay information remote-id dhcp relay information strategy display dhcp relay information dhcp relay information remote-idUse dhcp relay information remote-id to configure the padding mode and padding format for the Remote ID sub-option of Option 82. Use undo dhcp relay information remote-id to restore the default. Syntax dhcp relay information remote-id { normal [ format { ascii | hex } ] | string remote-id | sysname } undo dhcp relay information remote-id Default The padding mode is normal and the padding format is hex. Views Interface view Predefined user roles network-admin mdc-admin Parameters normal: Specifies the normal mode in which the padding content is the MAC address of the receiving interface. format: Specifies the padding format for the Remote ID sub-option. The default padding format is hex. ascii: Specifies the ASCII padding format. hex: Specifies the hex padding format. string remote-id: Specifies the string mode that uses a case-sensitive string of 1 to 63 characters as the content of the Remote ID sub-option. sysname: Specifies the sysname mode that uses the device name as the content of the Remote ID sub-option. You can set the device name by using the sysname command. Usage guidelines The padding format for the specified character string (string) or the device name (sysname) is always ASCII. The padding format for the normal mode is determined by the command. If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify the padding content for the Remote ID sub-option of Option 82 as device001. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp relay information enable [Sysname-Vlan-interface10] dhcp relay information strategy replace [Sysname-Vlan-interface10] dhcp relay information remote-id string device001 Related commands dhcp relay information enable dhcp relay information strategy display dhcp relay information dhcp relay information strategyUse dhcp relay information strategy to configure the strategy for the DHCP relay agent to handle messages containing Option 82. Use undo dhcp relay information strategy to restore the default handling strategy. Syntax dhcp relay information strategy { drop | keep | replace } undo dhcp relay information strategy Default The handling strategy for messages that contain Option 82 is replace. Views Interface view Predefined user roles network-admin mdc-admin Parameters drop: Drops DHCP messages that contain Option 82 messages. keep: Keeps the original Option 82 intact and forwards the DHCP messages. replace: Replaces the original Option 82 with the configured Option 82 before forwarding the DHCP messages. Usage guidelines This command takes effect only on DHCP requests that contain Option 82. For DHCP requests that do not contain Option 82, the DHCP relay agent always adds Option 82 to the requests before forwarding the requests to the DHCP server. If the handling strategy is replace, configure a padding mode and padding format for Option 82. If the handling strategy is keep or drop, you do not need to configure any padding mode or padding format. The settings do not take effect even if you configure them. Examples # Specify the handling strategy for Option 82 as keep. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp relay information enable [Sysname-Vlan-interface10] dhcp relay information strategy keep Related commands dhcp relay information enable display dhcp relay information dhcp relay master-server switch-delayUse dhcp relay master-server switch-delay to enable the switchback to the master DHCP server and set the switchback delay time. Use undo dhcp relay master-server switch-delay to restore the default. Syntax dhcp relay master-server switch-delay delay-time undo dhcp relay master-server switch-delay Default The DHCP relay agent does not switch back to the master DHCP server. Views Interface view Predefined user roles network-admin mdc-admin Parameters delay-time: Specifies the delay time in the range of 1 to 65535 minutes. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Configure the DHCP relay agent to switch back to the master DHCP server 3 minutes after it switches to a backup DHCP server on VLAN-interface 2. <Sysname> system-view [Sysname] interface vlan-interface 2 [Sysname-Vlan-interface2] dhcp relay master-server switch-delay 3 Related commands dhcp relay server-address algorithm dhcp relay release ipUse dhcp relay release ip to release a client IP address. Syntax dhcp relay release ip ip-address [ vpn-instance vpn-instance-name ] Views System view Predefined user roles network-admin mdc-admin Parameters ip-address: Specifies the IP address to be released. vpn-instance vpn-instance-name: Specifies the MPLS L3VPN instance to which the specified IP address belongs. The vpn-instance-name argument is a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command releases the IP address on the public network. Usage guidelines After you execute this command, the relay agent sends a DHCP-RELEASE packet to the DHCP server and removes the relay entry of the IP address. Upon receiving the packet, the server removes binding information about the specified IP address to release the IP address. Examples # Release IP address 1.1.1.1. <Sysname> system-view [Sysname] dhcp relay release ip 1.1.1.1 dhcp relay server-addressUse dhcp relay server-address to specifyDHCP servers on the DHCP relay agent. Use undo dhcp relay server-address to remove DHCP servers. Syntax dhcp relay server-address ip-address undo dhcp relay server-address [ ip-address ] Default No DHCP server is specified on the DHCP relay agent. Views Interface view Predefined user roles network-admin mdc-admin Parameters ip-address: Specifies the IP address of a DHCP server. The DHCP relay agent forwards DHCP packets received from DHCP clients to this DHCP server. Usage guidelines The specified IP address of the DHCP server must not reside on the same subnet as the IP address of the DHCP relay agent interface. Otherwise, the DHCP clients might fail to obtain IP addresses. You can specify a maximum of eight DHCP servers on an interface. The DHCP relay agent forwards the packets from the clients to all the specified DHCP servers. If you do not specify an IP address, the undo dhcp relay server-address command removes all DHCP servers on the interface. Examples # Specify DHCP server address 1.1.1.1 on VLAN-interface 10. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp relay server-address 1.1.1.1 Related commands dhcp select relay display dhcp relay interface dhcp relay server-address algorithmUse dhcp relay server-address algorithm to specify the DHCP server selecting algorithm. Use undo dhcp relay server-address algorithm to restore the default. Syntax dhcp relay server-address algorithm { master-backup | polling } undo dhcp relay server-address algorithm Default The polling algorithm is used. The DHCP relay agent forwards DHCP requests to all DHCP servers at the same time. Views Interface view Predefined user roles network-admin mdc-admin Parameters master-backup: Forwards DHCP requests to the master DHCP server first. If the master server is not available or does not have assignable IP addresses, the relay agent forwards DHCP requests to backup DHCP servers in the order they are specified. polling: Forwards DHCP requests to all DHCP servers at the same time. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify master-backup as the DHCP server selecting algorithm on VLAN-interface 2. <Sysname> system-view [Sysname] interface vlan-interface 2 [Sysname-Vlan-interface2] dhcp relay server-address algorithm master-backup Related commands dhcp relay dhcp-server timeout dhcp relay master-server switch-delay dhcp relay server-address remote-server algorithm dhcp relay source-addressUse dhcp relay source-address to specify the source IP address for DHCP requests. Use undo dhcp relay source-address to restore the default. Syntax dhcp relay source-address { ip-address | interface interface-type interface-number } undo dhcp relay source-address Default No source IP address is specified for DHCP requests. Views Interface view Predefined user roles network-admin mdc-admin Parameters ip-address: Specifies the source IP address. interface interface-type interface-number: Uses the IP address of an interface as the source IP address. The interface-type interface-number arguments specify an interface by its type and number. Usage guidelines This command is required if multiple relay interfaces share the same IP address or if a relay interface does not have routes to DHCP servers. You can use this command to specify the IP address of another interface, typically the loopback interface, on the DHCP relay agent as the source IP address for DHCP requests. The relay interface inserts the source IP address in the source IP address field as well as the giaddr field in DHCP requests. If multiple relay interfaces share the same IP address, you must also configure the relay interface to support Option 82. Upon receiving a DHCP request, the relay interface inserts the subnet information in sub-option 5 in Option 82. The DHCP server assigns an IP address according to sub-option 5. The DHCP relay agent looks up the output interface in the MAC address table to forward the DHCP reply. If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify 1.1.1.1 as the source IP address for DHCP requests on VLAN-interface 2. <Sysname> system-view [Sysname] interface vlan-interface 2 [Sysname-Vlan-interface2] dhcp relay source-address 1.1.1.1 Related commands dhcp select relay dhcp smart-relay enableUse dhcp smart-relay enable to enable the DHCP smart relay feature. Use undo dhcp smart-relay enable to disable the DHCP smart relay feature. Syntax dhcp smart-relay enable undo dhcp smart-relay enable Default The DHCP smart relay feature is disabled. Views System view Predefined user roles network-admin mdc-admin Usage guidelines The smart relay feature allows the relay agent to use secondary IP addresses as the gateway address when the DHCP server does not reply the DHCP-OFFER message. The relay agent initially inserts its primary IP address in the giaddr field before forwarding a request to the DHCP server. If no DHCP-OFFER is returned after two retries, the relay agent switches to secondary IP addresses. Without this feature, the relay agent always uses the primary IP address as the gateway address. Examples # Enable the DHCP smart relay feature. <Sysname> system-view [Sysname] dhcp smart-relay enable Related commands dhcp select gateway-list dhcp-server timeoutUse dhcp-server timeout to set the DHCP server response timeout time for DHCP server switchover. Use undo dhcp-server timeout to restore the default. Syntax dhcp-server timeout time undo dhcp-server timeout Default The DHCP server response timeout time is 30 seconds. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters time: Specifies the DHCP server response timeout time in the range of 30 to 65535 seconds. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Set the DHCP server response timeout time to 60 seconds for DHCP server switchover in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] dhcp-server timeout 60 Related commands remote-server algorithm display dhcp relay check mac-addressUse display dhcp relay check mac-address to display MAC address check entries on the relay agent. Syntax display dhcp relay check mac-address Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Examples # Display MAC address check entries on the DHCP relay agent. <Sysname> display dhcp relay check mac-address Source-MAC Interface Aging-time 23f3-1122-adf1 Vlan2 10 23f3-1122-2230 Vlan3 30 Table 9 Command output
display dhcp relay client-informationUse display dhcp relay client-information to display relay entries on the relay agent. Syntax display dhcp relay client-information [ interface interface-type interface-number | ip ip-address [ vpn-instance vpn-instance-name ] ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters interface interface-type interface-number: Displays relay entries on the specified interface. If you do not specify an interface, this command displays relay entries on all interfaces. ip ip-address: Displays the relay entry for the specified IP address. If you do not specify an IP address, this command displays relay entries for all IP addresses. vpn-instance vpn-instance-name: Specifies the MPLS L3VPN instance to which the specified IP address belongs. The vpn-instance-name argument is a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command displays the relay entry for the specified IP address on the public network. Usage guidelines The DHCP relay agent records relay entries only after you configure the dhcp relay client-information record command. Examples # Display all relay entries on the relay agent. <Sysname> display dhcp relay client-information Total number of client-information items: 2 Total number of dynamic items: 1 Total number of temporary items: 1 IP address MAC address Type Interface VPN name 10.1.1.5 00e0-0000-0000 Temporary Vlan2 N/A Table 10 Command output
Related commands dhcp relay client-information record reset dhcp relay client-information display dhcp relay informationUse display dhcp relay information to display Option 82 configuration information for the DHCP relay agent. Syntax display dhcp relay information [ interface interface-type interface-number ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters interface interface-type interface-number: Displays Option 82 configuration information for the specified interface. If you do not specify an interface, this command displays Option 82 configuration information about all interfaces. Examples # Display Option 82 configuration information for all interfaces. <Sysname> display dhcp relay information Interface: Vlan-interface100 Status: Enable Strategy: Replace Circuit ID Pattern: Verbose Remote ID Pattern: Sysname Circuit ID format-type: Undefined Remote ID format-type: ASCII Node identifier: aabbcc Interface: Vlan-interface200 Status: Enable Strategy: Replace Circuit ID Pattern: User Defined Remote ID Pattern: User Defined Circuit ID format-type: ASCII Remote ID format-type: ASCII User defined: Circuit ID: vlan100 Remote ID: device001 Table 11 Command output
display dhcp relay server-addressUse display dhcp relay server-addressto display DHCP server addresses configured on an interface. Syntax display dhcp relay server-address [ interface interface-type interface-number ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters interface interface-type interface-number: Displays DHCP server addresses on the specified interface. If you do not specify an interface, this command displays DHCP server addresses on all interfaces. Examples # Display DHCP server addresses on all interfaces. <Sysname> display dhcp relay server-address Interface name Server IP address Vlan2 2.2.2.2 Table 12 Command output
Related commands dhcp relay server-address display dhcp relay statisticsUse display dhcp relay statistics to display DHCP packet statistics on the DHCP relay agent. Syntax display dhcp relay statistics [ interface interface-type interface-number ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters interface interface-type interface-number: Displays DHCP packet statistics on the specified interface. If you do not specify an interface, this command displays all DHCP packet statistics on the DHCP relay agent. Examples # Display all DHCP packet statistics on the DHCP relay agent. <Sysname> display dhcp relay statistics DHCP packets dropped: 0 DHCP packets received from clients: 0 DHCPDISCOVER: 0 DHCPREQUEST: 0 DHCPINFORM: 0 DHCPRELEASE: 0 DHCPDECLINE: 0 BOOTPREQUEST: 0 DHCP packets received from servers: 0 DHCPOFFER: 0 DHCPACK: 0 DHCPNAK: 0 BOOTPREPLY: 0 DHCP packets relayed to servers: 0 DHCPDISCOVER: 0 DHCPREQUEST: 0 DHCPINFORM: 0 DHCPRELEASE: 0 DHCPDECLINE: 0 BOOTPREQUEST: 0 DHCP packets relayed to clients: 0 DHCPOFFER: 0 DHCPACK: 0 DHCPNAK: 0 BOOTPREPLY: 0 DHCP packets sent to servers: 0 DHCPDISCOVER: 0 DHCPREQUEST: 0 DHCPINFORM: 0 DHCPRELEASE: 0 DHCPDECLINE: 0 BOOTPREQUEST: 0 DHCP packets sent to clients: 0 DHCPOFFER: 0 DHCPACK: 0 DHCPNAK: 0 BOOTPREPLY: 0 Related commands reset dhcp relay statistics gateway-listUse gateway-list to specify gateway addresses for DHCP clients in a DHCP address pool. Use undo gateway-list to remove gateway addresses from a DHCP address pool. Syntax gateway-list ip-address&<1-64> [ export-route ] undo gateway-list [ ip-address&<1-64> ] [ export-route ] Default No gateway address is specified in a DHCP address pool. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip-address&<1-64>: Specifies a space-separated list of up to 64 addresses. export-route: Binds the gateways to the device's MAC address in the address management module. The ARP module will use the entries to reply to ARP requests from the DHCP clients. If you do not specify this keyword, the gateways will not be bound to the device's MAC address. Usage guidelines DHCP clients of the same access type can be classified into different types by their locations. In this case, the relay interface typically has no IP address configured. You can use the gateway-list command to specify gateway addresses for clients matching the same DHCP address pool and bind the gateway addresses to the device's MAC address. Upon receiving a DHCP DISCOVER or REQUEST from a client that matches a DHCP address pool, the relay agent processes the packet as follows: 1. Fills the giaddr field of the packet with a specified gateway address. 2. Forwards the packet to all DHCP servers in the matching DHCP address pool. The DHCP servers select a DHCP address pool according to the gateway address. Examples # Specify gateway address 10.1.1.1 in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] gateway-list 10.1.1.1 Related commands dhcp smart-relay enable master-server switch-delayUse master-server switch-delay to enable the switchback to the master DHCP server and set the switchback delay time. Use undo master-server switch-delay to restore the default. Syntax master-server switch-delay delay-time undo master-server switch-delay Default The DHCP relay agent does not switch back to the master DHCP server. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters delay-time: Specifies the delay time in the range of 1 to 65535 minutes. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Configure the DHCP relay agent to switch back to the master DHCP server 3 minutes after it switches to a backup DHCP server in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] master-server switch-delay 3 Related commands remote-server algorithm remote-serverUse remote-server to specify DHCP servers for a DHCP address pool. Use undo remote-server to remove DHCP servers from a DHCP address pool. Syntax remote-server ip-address&<1-8> undo remote-server [ ip-address&<1-8> ] Default No DHCP server is specified for the DHCP address pool. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters ip-address&<1-8>: Specifies a space-separated list of up to eight DHCP server addresses. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. If you do not specify a DHCP server address, the undo remote-server command removes all DHCP servers in the DHCP address pool. Examples # Specify DHCP server 10.1.1.1 for DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] remote-server 10.1.1.1 remote-server algorithmUse remote-server algorithm to specify the DHCP server selecting algorithm. Use undo remote-server algorithm to restore the default. Syntax remote-server algorithm { master-backup | polling } undo remote-server algorithm Default The polling algorithm is used. The DHCP relay agent forwards DHCP requests to all DHCP servers at the same time. Views DHCP address pool view Predefined user roles network-admin mdc-admin Parameters master-backup: Forwards DHCP requests to the master DHCP server first. If the master server is not available or does not have assignable IP addresses, the relay agent forwards DHCP requests to backup DHCP servers in the order they are specified. polling: Forwards DHCP requests to all DHCP servers at the same time. Usage guidelines If you execute this command multiple times, the most recent configuration takes effect. Examples # Specify master-backup as the DHCP server selecting algorithm in DHCP address pool 0. <Sysname> system-view [Sysname] dhcp server ip-pool 0 [Sysname-dhcp-pool-0] remote-server algorithm master-backup Related commands dhcp relay server-address algorithm dhcp-server timeout master-server switch-delay remote-server reset dhcp relay client-informationUse reset dhcp relay client-information to clear relay entries on the DHCP relay agent. Syntax reset dhcp relay client-information [ interface interface-type interface-number | ip ip-address [ vpn-instance vpn-instance-name ] ] Views User view Predefined user roles network-admin mdc-admin Parameters interface interface-type interface-number: Clears relay entries on the specified interface. If you do not specify an interface, this command clears relay entries on all interfaces. ip ip-address: Clears the relay entry for the specified IP address. If you do not specify an IP address, this command clears relay entries for all IP addresses. vpn-instance vpn-instance-name: Specifies the MPLS L3VPN instance to which the specified IP address belongs. The vpn-instance-name argument is a case-sensitive string of 1 to 31 characters. If you do not specify a VPN instance, this command clears the relay entry for the specified IP address on the public network. Examples # Clear all relay entries on the DHCP relay agent. <Sysname> reset dhcp relay client-information Related commands display dhcp relay client-information reset dhcp relay statisticsUse reset dhcp relay statistics to clear relay agent statistics. Syntax reset dhcp relay statistics [ interface interface-type interface-number ] Views User view Predefined user roles network-admin mdc-admin Parameters interface interface-type interface-number: Specifies an interface by its type and number. If you do not specify an interface, this command clears all DHCP relay agent statistics. Examples # Clear all DHCP relay agent statistics. <Sysname> reset dhcp relay statistics Related commands display dhcp relay statistics DHCP client commandsdhcp client dad enableUse dhcp client dad enable to enable duplicate address detection. Use undo dhcp client dad enable to disable duplicate address detection. Syntax dhcp client dad enable undo dhcp client dad enable Default Duplicate address detection is enabled on an interface. Views System view Predefined user roles network-admin mdc-admin Usage guidelines DHCP client detects IP address conflict through ARP packets. An attacker can act as the IP address owner to send an ARP reply. This makes the client unable to use the IP address assigned by the server. As a best practice, disable duplicate address detection when ARP attacks exist on the network. Examples # Disable the duplicate address. <Sysname> system-view [Sysname] undo dhcp client dad enable dhcp client dscpUse dhcp client dscp to set the DSCP value for DHCP packets sent by the DHCP client. Use undo dhcp client dscp to restore the default. Syntax dhcp client dscp dscp-value undo dhcp client dscp Default The DSCP value is 56 in DHCP packets sent by the DHCP client. Views System view Predefined user roles network-admin mdc-admin Parameters dscp-value: Sets the DSCP value for DHCP packets, in the range of 0 to 63. Usage guidelines The DSCP value of a packet specifies the priority level of the packet and affects the transmission priority of the packet. A bigger DSCP value represents a higher priority. Examples # Set the DSCP value to 30 for DHCP packets sent by the DHCP client. <Sysname> system-view [Sysname] dhcp client dscp 30 dhcp client identifierUse dhcp client identifier to configure a DHCP client ID for an interface. Use undo dhcp client identifier to restore the default. Syntax dhcp client identifier { ascii ascii-string| hex hex-string | mac interface-type interface-number } undo dhcp client identifier Default An interface generates the DHCP client ID based on its MAC address. If the interface has no MAC address, it uses the MAC address of the first Ethernet interface to generate its client ID. Views Interface view Predefined user roles network-admin mdc-admin Parameters ascii ascii-string: Specifies a case-sensitive ASCII string of 1 to 63 characters as the client ID. hex hex-string: Specifies a hexadecimal number of 4 to 64 characters as the client ID. mac interface-type interface-number: Uses the MAC address of the specified interface as a DHCP client ID. The interface-type interface-number argument specifies an interface by its type and number. Usage guidelines A DHCP client ID is added to the DHCP option 61. A DHCP server can specify IP addresses for clients based on the DHCP client ID. You can specify a DHCP client ID by performing one of the following operations: · Naming an ASCIIstring or hexadecimal number as the client ID. · Using the MAC address of an interface to generate a client ID. Whichever method you use, make sure the IDs for different DHCP clients are unique. Examples # Use a hexadecimal number of FFFFFFFF as the client ID for VLAN-interface 10. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] dhcp client identifier hex FFFFFFFF Related commands display dhcp client display dhcp clientUse display dhcp client to display DHCP client information. Syntax display dhcp client [ verbose ] [ interface interface-type interface-number ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters verbose: Displays detailed DHCP client information. If you do not specify this keyword, the command displays brief DHCP client information. interface interface-type interface-number: Specifies an interface by its type and number. If you do not specify an interface, this command displays DHCP client information on all interfaces. Examples # Display brief DHCP client information on all interfaces. <Sysname> display dhcp client Vlan-interface10 DHCP client information: Current state: BOUND Allocated IP: 40.1.1.20 255.255.255.0 Allocated lease: 259200 seconds, T1: 129600 seconds, T2: 226800 seconds DHCP server: 40.1.1.2 # Display detailed DHCP client information on all interfaces. <Sysname> display dhcp client verbose Vlan-interface10 DHCP client information: Current state: BOUND Allocated IP: 40.1.1.20 255.255.255.0 Allocated lease: 259200 seconds, T1: 129600 seconds, T2: 226800 seconds Lease from May 21 19:00:29 2012 to May 31 19:00:29 2012 DHCP server: 40.1.1.2 Transaction ID: 0x1c09322d Default router: 40.1.1.2 Classless static routes: Destination: 1.1.0.1, Mask: 255.0.0.0, NextHop: 192.168.40.16 Destination: 10.198.122.63, Mask: 255.255.255.255, NextHop: 192.168.40.16 DNS servers: 44.1.1.11 44.1.1.12 Domain name: ddd.com Boot servers: 200.200.200.200 1.1.1.1 ACS parameter: URL: http://192.168.1.1:7547/acs Username: bims Password: ****** Client ID type: acsii(type value=00) Client ID value: 000c.29d3.8659-Vlan10 Client ID (with type) hex: 0030-3030-632e-3239- 6433-2e38-3635-392d- 4574-6830-2f30-2f32 T1 will timeout in 1 day 11 hours 58 minutes 52 seconds. Table 13 Command output
Related commands dhcp client identifier ip address dhcp-alloc ip address dhcp-allocUse ip address dhcp-alloc to configure an interface to use DHCP for IP address acquisition. Use undo ip address dhcp-alloc to cancel an interface from using DHCP. Syntax ip address dhcp-alloc undo ip address dhcp-alloc Default An interface does not use DHCP for IP address acquisition. Views Interface view Predefined user roles network-admin mdc-admin Usage guidelines When you execute the undo ip address dhcp-alloc command, the interface sends a DHCP-RELEASE message to release the IP address obtained through DHCP. If the interface is down, the message cannot be sent out. This situation can occur when a subinterface obtained an IP address through DHCP, and the shutdown command is executed on its primary interface. The subinterface will fail to send a DHCP-RELEASE message. Examples # Configure VLAN-interface 10 to use DHCP for IP address acquisition. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] ip address dhcp-alloc DHCP snooping commandsDHCP snooping works between the DHCP client and the DHCP server or between the DHCP client and the relay agent. DHCP snooping does not work between the DHCP server and the DHCP relay agent. dhcp snooping binding database filenameUse dhcp snooping binding database filename to configure the DHCP snooping device to back up DHCP snooping entries to a file. Use undo dhcp snooping binding database filename to restore the default. Syntax dhcp snooping binding database filename { filename | url url [ username username [ password { cipher | simple } string ] ] } undo dhcp snooping binding database filename Default The DHCP snooping device does not back up DHCP snooping entries. Views System view Predefined user roles network-admin mdc-admin Parameters filename: Specifies the name of a local backup file. For information about the filename argument, see Fundamentals Configuration Guide. url url: Specifies the URL of a remote backup file, a case-sensitive string of 1 to 255 characters. Do not include a username or password in the URL. Supported path format type varies by server. username username: Specifies the username for accessing the URL of the remote backup file, a case-sensitive string of 1 to 32 characters. Do not specify this option if a username is not required for accessing the URL. cipher: Specifies a password in encrypted form. simple: Specifies a password in plaintext form. For security purposes, the password specified in plaintext form will be stored in encrypted form. string: Specifies the password. Its plaintext form is a case-sensitive string of 1 to 32 characters. Its encrypted form is a case-sensitive string of 1 to 73 characters. Do not specify this argument if a password is not required for accessing the URL of the remote backup file. Usage guidelines This command automatically creates the file if you specify a nonexistent file. With this command executed, the DHCP snooping device backs up DHCP snooping entries immediately and runs auto backup. The DHCP snooping device, by default, waits 300 seconds after a DHCP snooping entry change to update the backup file. To change the waiting period, use the dhcp snooping binding database update interval command. If no DHCP snooping entry changes, the backup file is not updated. As a best practice, back up the DHCP snooping entries to a remote file. If you use the local storage medium, the frequent erasing and writing might damage the medium and then cause the DHCP snooping device to malfunction. When the file is on a remote device, follow these restrictions and guidelines to specify the URL, username, and password: · If the file is on an FTP server, enter URL in the following format: ftp://server address:port/file path, where the port number is optional. · If the file is on a TFTP server, enter URL in the following format: tftp://server address:port/file path, where the port number is optional. · The username and password must be the same as those configured on the FTP server. If the server authenticates only the username, the password can be omitted. · If the IP address of the server is an IPv6 address, enclose the address in a pair of brackets, for example, ftp://[1::1]/database.dhcp. · You can also specify the DNS domain name for the server address field, for example, ftp://company/database.dhcp. Examples # Configure the DHCP snooping device to back up DHCP snooping entries to file database.dhcp. <Sysname> system-view [Sysname] dhcp snooping binding database filename database.dhcp # Configure the DHCP snooping device to back up DHCP snooping entries to file database.dhcp in the working directory of the FTP server at 10.1.1.1. <Sysname> system-view [Sysname] dhcp snooping binding database filename url ftp://10.1.1.1/database.dhcp username 1 password simple 1 # Configure the DHCP snooping device to back up DHCP snooping entries to file database.dhcp in the working directory of the TFTP server at 10.1.1.1. <Sysname> system-view [Sysname] dhcp snooping binding database filename tftp://10.1.1.1/database.dhcp Related commands dhcp snooping binding database update interval dhcp snooping binding database update intervalUse dhcp snooping binding database update interval to set the waiting time for the DHCP snooping device to update the backup file after a DHCP snooping entry change. Use undo dhcp snooping binding database update interval to restore the default. Syntax dhcp snooping binding database update interval interval undo dhcp snooping binding database update interval Default The DHCP snooping device waits 300 seconds to update the backup file after a DHCP snooping entry change. If no DHCP snooping entry changes, the backup file is not updated. Views System view Predefined user roles network-admin mdc-admin Parameters interval: Specifies the waiting time in seconds, in the range of 60 to 864000. Usage guidelines When a DHCP snooping entry is learned, updated, or removed, the waiting period starts. The DHCP snooping device updates the backup file when the waiting period is reached. All changed entries during the period will be saved to the backup file. The waiting time takes effect only after you configure the DHCP snooping entry auto backup by using the dhcp snooping binding database filename command. Examples # Set the waiting time to 600 seconds for the DHCP snooping device to update the backup file. <Sysname> system-view [Sysname] dhcp snooping binding database update interval 600 Related commands dhcp snooping binding database filename dhcp snooping binding database update nowUse dhcp snooping binding database update now to manually save DHCP snooping entries to the backup file. Syntax dhcp snooping binding database update now Views System view Predefined user roles network-admin mdc-admin Usage guidelines Each time this command is executed, the DHCP snooping entries are saved to the backup file. This command takes effect only after you configure the DHCP snooping auto backup by using the dhcp snooping binding database filename command. Examples # Manually save DHCP snooping entries to the backup file. <Sysname> system-view [Sysname] dhcp snooping binding database update now Related commands dhcp snooping binding database filename dhcp snooping binding recordUse dhcp snooping binding record to enable recording of client information in DHCP snooping entries. Use undo dhcp snooping binding record to disable recording of client information in DHCP snooping entries. Syntax dhcp snooping binding record undo dhcp snooping binding record Default DHCP snooping does not record client information. Views Layer 2 Ethernet interface/Layer 2 aggregate interface view Predefined user roles network-admin mdc-admin Usage guidelines This command enables DHCP snooping on the port directly connecting to the clients to record client information in DHCP snooping entries. Examples # Enable the recording of client information in DHCP snooping entries on Ten-GigabitEthernet 1/0/1. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping binding record dhcp snooping check mac-addressUse dhcp snooping check mac-address to enable MAC address check for DHCP snooping. Use undo dhcp snooping check mac-address to disable MAC address check for DHCP snooping. Syntax dhcp snooping check mac-address undo dhcp snooping check mac-address Default MAC address check for DHCP snooping is disabled. Views Layer 2 Ethernet interface/Layer 2 aggregate interface view Layer 3 Ethernet interface/Layer 3 aggregate interface view Predefined user roles network-admin mdc-admin Usage guidelines With MAC address check enabled, DHCP snooping compares the chaddr field of a received DHCP request with the source MAC address field in the frame header. If they are the same, DHCP snooping considers this request valid and forwards it to the DHCP server. If they are not the same, DHCP snooping discards the DHCP request. Examples # Enable MAC address check for DHCP snooping. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping check mac-address dhcp snooping check request-messageUse dhcp snooping check request-message to enable DHCP-REQUEST check for DHCP snooping. Use undo dhcp snooping check request-message to disable DHCP-REQUEST check for DHCP snooping. Syntax dhcp snooping check request-message undo dhcp snooping check request-message Default DHCP-REQUEST check for DHCP snooping is disabled. Views Layer 2 Ethernet interface/Layer 2 aggregate interface view Predefined user roles network-admin mdc-admin Usage guidelines DHCP-REQUEST packets include lease renewal packets, DHCP-DECLINE packets, and DHCP-RELEASE packets. This feature prevents unauthorized clients that forge DHCP-REQUEST packets from attacking the DHCP server. With this feature enabled, DHCP snooping looks for a matching DHCP snooping entry for each received DHCP-REQUEST message. · If a match is found, DHCP snooping compares the entry with the message. If they have consistent information, DHCP snooping considers the packet valid and forwards it to the DHCP server. If they have different information, DHCP snooping considers the message invalid and discards it. · If no match is found, DHCP snooping forwards the message to the DHCP server. Examples # Enable DHCP-REQUEST check for DHCP snooping. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping check request-message dhcp snooping denyUse dhcp snooping deny to configure a port as DHCP packet blocking port. Use undo dhcp snooping deny to restore the default. Syntax dhcp snooping deny undo dhcp snooping deny Default A port does not block DHCP requests. Views Layer 2 Ethernet interface/Layer 2 aggregate interface view Predefined user roles network-admin mdc-admin Usage guidelines A DHCP packet blocking port drops all incoming DHCP requests. Examples # Configure Ten-GigabitEthernet 1/0/1 as a DHCP packet blocking port. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping deny dhcp snooping enableUse dhcp snooping enable to enable DHCP snooping. Use undo dhcp snooping enable to disable DHCP snooping. Syntax dhcp snooping enable undo dhcp snooping enable Default DHCP snooping is disabled. Views System view Predefined user roles network-admin mdc-admin Usage guidelines Use the DHCP snooping feature together with the trusted port configuration. Trusted ports forward responses from DHCP servers and untrusted ports discard responses from DHCP servers. This mechanism ensures that DHCP clients obtain IP addresses from authorized DHCP servers. When DHCP snooping is disabled, all ports on the device forward responses from DHCP servers. Examples # Enable DHCP snooping. <Sysname> system-view [Sysname] dhcp snooping enable dhcp snooping information circuit-idUse dhcp snooping information circuit-id to configure the padding mode and padding format for the Circuit ID sub-option. Use undo dhcp snooping information circuit-id to restore the default. Syntax dhcp snooping information circuit-id { [ vlan vlan-id] string circuit-id | { normal | verbose [ node-identifier { mac | sysname | user-defined node-identifier} ] } [ format { ascii | hex } ] } undo dhcp snooping information circuit-id [ vlan vlan-id ] Default The padding mode is normal and the padding format is hex. Views Layer 2 Ethernet interface view Layer 2 aggregate interface view Predefined user roles network-admin mdc-admin Parameters vlan vlan-id: Pads the Circuit ID sub-option for packets received from the specified VLAN. If you do not specify a VLAN, the device pads the Circuit ID sub-option for packets received from the default VLAN. string circuit-id: Specifies the string mode, in which the padding content for the Circuit ID sub-option is a case-sensitive string of 3 to 63 characters. normal: Specifies the normal mode. The padding content includes the VLAN ID and interface number. verbose: Specifies the verbose mode. The padding content includes the node identifier, interface information, and VLAN ID. The default node identifier is the MAC address of the access node. The default interface information consists of the Ethernet type (fixed to eth), chassis number, slot number, sub-slot number, and interface number. node-identifier { mac | sysname | user-defined node-identifier }: Specifies the access node identifier. · mac: Uses the MAC address of the access node as the node identifier. · sysname: Uses the device name as the node identifier. You can set the device name by using the sysname command in system view. The padding format for the device name is always ASCII regardless of the specified padding format.
· user-defined node-identifier: Uses a case-sensitive string of 1 to 50 characters as the node identifier. The padding format for the specified character string is always ASCII regardless of the specified padding format. format: Specifies the padding format for the Circuit ID sub-option. ascii: Specifies the ASCII padding format. hex: Specifies the hex padding format. Usage guidelines The Circuit ID sub-option cannot carry information about interface splitting or subinterfaces. For more information about interface splitting and subinterfaces, see Interface Configuration Guide. If you execute this command multiple times, the most recent configuration takes effect. The padding format for the string mode, the normal mode, or the verbose mode varies by command configuration. Table 14 shows how the padding format is determined for different modes. Table 14 Padding format for different modes
Examples # Configure verbose as the padding mode, device name as the node identifier, and ASCII as the padding format for the Circuit ID sub-option. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information enable [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information strategy replace [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information circuit-id verbose node-identifier sysname format ascii Related commands dhcp snooping information enable dhcp snooping information strategy display dhcp snooping information dhcp snooping information enableUse dhcp snooping information enable to enable DHCP snooping to support Option 82. Use undo dhcp snooping information enable to disable this feature. Syntax dhcp snooping information enable undo dhcp snooping information enable Default DHCP snooping does not support Option 82. Views Layer 2 Ethernet interface view Layer 2 aggregate interface view Predefined user roles network-admin mdc-admin Usage guidelines This command enables DHCP snooping to add Option 82 into DHCP requests that do not contain Option 82 before forwarding the requests to the DHCP server. The content of Option 82 is determined by the dhcp snooping information circuit-id and dhcp snooping information remote-id commands. If the received DHCP request packets contain Option 82, DHCP snooping handles the packets according to the strategy configured by the dhcp snooping information strategy command. Examples # Enable DHCP snooping to support Option 82. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information enable Related commands dhcp snooping information circuit-id dhcp snooping information remote-id dhcp snooping information strategy dhcp snooping information remote-idUse dhcp snooping information remote-id to configure the padding mode and padding format for the Remote ID sub-option. Use undo dhcp snooping information remote-id to restore the default. Syntax dhcp snooping information remote-id { normal [ format { ascii | hex } ] | [ vlan vlan-id ] { string remote-id | sysname } } undo dhcp snooping information remote-id [ vlan vlan-id ] Default The padding mode is normal and the padding format is hex. Views Layer 2 Ethernet interface view Layer 2 aggregate interface view Predefined user roles network-admin mdc-admin Parameters vlan vlan-id:Pads the Remote ID sub-option for packets received from the specified VLAN. If you do not specify a VLAN, the device pads the Remote ID sub-option for packets received from the default VLAN. string remote-id: Specifies the string mode that uses a case-sensitive string of 1 to 63 characters as the content of the Remote ID sub-option. sysname: Specifies the sysname mode that uses the device name as the Remote ID sub-option. You can configure the device name by using the sysname command in system view. normal: Specifies the normal mode. The padding content is the MAC address of the receiving interface. format: Specifies the padding format for the Remote ID sub-option. The default padding format is hex. ascii: Specifies the ASCII padding format. hex: Specifies the hex padding format. Usage guidelines DHCP snooping uses ASCII to pad the specified string or device name for the Remote ID sub-option. The padding format for the normal padding mode is determined by the command configuration. If you execute this command multiple times, the most recent configuration takes effect. Examples # Pad the Remote ID sub-option with a characterstring of device001. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information enable [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information strategy replace [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information remote-id string device001 Related commands dhcp snooping information enable dhcp snooping information strategy display dhcp snooping information dhcp snooping information strategyUse dhcp snooping information strategy to configure the handling strategy for Option 82 in request messages. Use undo dhcp snooping information strategy to restore the default. Syntax dhcp snooping information strategy { drop | keep | replace } undo dhcp snooping information strategy Default The handling strategy for Option 82 in request messages is replace. Views Layer 2 Ethernet interface view Layer 2 aggregate interface view Predefined user roles network-admin mdc-admin Parameters drop: Drops DHCP messages that contain Option 82. keep: Keeps the original Option 82 intact and forwards the DHCP messages. replace: Replaces the original Option 82 with the configured Option 82 before forwarding the DHCP messages. Usage guidelines This command takes effect only on DHCP requests that contain Option 82. For DHCP requests that do not contain Option 82, the DHCP snooping device always adds Option 82 into the requests before forwarding them to the DHCP server. If the handling strategy is replace, configure a padding mode and a padding format for Option 82. If the handling strategy is keep or drop, you do not need to configure a padding mode or padding format for Option 82. Examples # Specify the handling strategy for Option 82 in request messages as keep. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information enable [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping information strategy keep Related commands dhcp snooping information circuit-id dhcp snooping information remote-id dhcp snooping log enableUse dhcp snooping log enable to enable DHCP snooping logging. Use undo dhcp snooping log enable to disable DHCP snooping logging. Syntax dhcp snooping log enable undo dhcp snooping log enable Default DHCP snooping logging is disabled. Views System view Predefined user roles network-admin mdc-admin Usage guidelines This command enables the DHCP snooping device to generate DHCP snooping logs and send them to the information center. For information about the log destination and output rule configuration in the information center, see Network Management and Monitoring Configuration Guide. As a best practice, disable this feature if the log generation affects the device performance. Examples # Enable DHCP snooping logging. <Sysname> system-view [Sysname] dhcp snooping log enable dhcp snooping max-learning-numUse dhcp snooping max-learning-numto set the maximum number of DHCP snooping entries that an interface can learn. Use undo dhcp snooping max-learning-num to restore the default. Syntax dhcp snooping max-learning-num max-number undo dhcp snooping max-learning-num Default The maximum number of DHCP snooping entries for an interface to learn is unlimited. Views Layer 2 Ethernet interface/Layer 2 aggregate interface view Layer 3 Ethernet interface/Layer 3 aggregate interface view Predefined user roles network-admin mdc-admin Parameters max-number: Specifies the maximum number of DHCP snooping entries for an interface to learn. The value range is 1 to 4294967295. Usage guidelines When an interface learns the maximum number of DHCP snooping entries, the interface stops learning DHCP snooping entries. This does not affect the operating of the DHCP snooping feature. Examples # Allow Layer 2 Ethernet interface Ten-GigabitEthernet 1/0/1 to learn a maximum of 10 DHCP snooping entries. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping max-learning-num 10 dhcp snooping rate-limitUse dhcp snooping rate-limit to enable DHCP snooping packet rate limit on an interface and set the limit value. Use undo dhcp snooping rate-limit to disable DHCP snooping packet rate limit. Syntax dhcp snooping rate-limit rate undo dhcp snooping rate-limit Default The DHCP snooping packet rate limit is disabled on an interface. Views Layer 2 Ethernet interface/Layer 2 aggregate interface view Predefined user roles network-admin mdc-admin Parameters rate: Specifies the maximum rate in Kbps. The value range is 64 to 512. Usage guidelines This command takes effect only when DHCP snooping is enabled. With the rate limit feature, the interface discards DHCP packets that exceed the maximum rate. The rate configured on a Layer 2 aggregate interface applies to all members of the aggregate interface. If a member interface leaves the aggregation group, it uses the rate configured in its Ethernet interface view. The device-supported maximum rate is an integer multiple of eight. If you set the maximum rate to 67, the value 64 or 72 takes effect. Examples # Set the maximum rate to 64 Kbps at which Layer 2 Ethernet interface Ten-GigabitEthernet 1/0/1 can receive DHCP packets. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping rate-limit 64 dhcp snooping trustUse dhcp snooping trust to configure a port as a trusted port. Use undo dhcp snooping trust to restore the default state of a port. Syntax dhcp snooping trust undo dhcp snooping trust Default After you enable DHCP snooping, all ports are untrusted. Views Layer 2 Ethernet interface/Layer 2 aggregate interface view Layer 3 Ethernet interface/Layer 3 aggregate interface view Predefined user roles network-admin mdc-admin Usage guidelines Specify the ports facing the DHCP server as trusted ports and specify the other ports as untrusted ports so DHCP clients can obtain valid IP addresses. Examples # Specify Layer 2 Ethernet interface Ten-GigabitEthernet 1/0/1 as a trusted port. <Sysname> system-view [Sysname] interface ten-gigabitethernet 1/0/1 [Sysname-Ten-GigabitEthernet1/0/1] dhcp snooping trust Related commands display dhcp snooping trust display dhcp snooping bindingUse display dhcp snooping binding to display DHCP snooping entries. Syntax display dhcp snooping binding [ ip ip-address [ vlan vlan-id ] ] [ verbose ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters ip ip-address: Displays the DHCP snooping entry for the specified IP address. If you do not specify an IP address, this command displays DHCP snooping entries for all IP addresses. vlan vlan-id: Specifies the VLAN ID where the IP address resides. If you do not specify a VLAN, this command displays DHCP snooping entries for the IP address in all VLANs. verbose: Displays detailed DHCP snooping entry information. If you do not specify this keyword, the command displays summary DHCP snooping entry information. Examples # Display summary information about all DHCP snooping entries. <Sysname> display dhcp snooping binding 2 DHCP snooping entries found IP address MAC address Lease VLAN SVLAN Interface =============== ============== ============ ===== ===== ================= 1.1.1.7 0000-0101-0107 16907533 2 3 XGE1/0/1 1.1.1.11 0000-0101-010b 16907537 2 3 XGE1/0/3 # Display detailed information about all DHCP snooping entries. <Sysname> display dhcp snooping binding verbose IP address: 1.1.1.7 MAC address: 0000-0101-0107 Lease: 16907553 seconds VLAN: 2 SVLAN: 3 Interface: Ten-GigabitEthernet1/0/1 Parameter requested list: 03 06 21 IP address: 1.1.1.104 MAC address: 0000-0101-010b Lease: 16907537 seconds VLAN: 2 SVLAN: 3 Interface: Ten-GigabitEthernet1/0/3 Parameter requested list: 37 0B 01 0F 03 06 2C 2E 2F 1F 21 F9 2B Table 15 Command output
Related commands dhcp snooping enable reset dhcp snooping binding display dhcp snooping binding databaseUse display dhcp snooping binding database to display information about DHCP snooping entry auto backup. Syntax display dhcp snooping binding database Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Examples # Display information about DHCP snooping entry auto backup. <Sysname> display dhcp snooping binding database File name : database.dhcp Username : Password : Update interval : 600 seconds Latest write time : Feb 27 18:48:04 2012 Status : Last write succeeded. Table 16 Command output
display dhcp snooping informationUse display dhcp snooping information to display Option 82 configuration on the DHCP snooping device. Syntax display dhcp snooping information { all | interface interface-type interface-number } Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters all: Displays Option 82 configuration on all Layer 2 Ethernet interfaces. interface interface-type interface-number: Specifies an interface by its type and number. Examples # Display Option 82 configuration on all interfaces. <Sysname> display dhcp snooping information all Interface: Bridge-Aggregation1 Status: Disable Strategy: Drop Circuit ID: Padding format: User Defined User defined: abcd Format: ASCII Remote ID: Padding format: Normal Format: ASCII VLAN 10: Circuit ID: abcd Remote ID: company Table 17 Command output
display dhcp snooping packet statisticsUse display dhcp snooping packet statistics to display DHCP packet statistics for DHCP snooping. Syntax In standalone mode: display dhcp snooping packet statistics [ slot slot-number ] In IRF mode: display dhcp snooping packet statistics [ chassis chassis-number slot slot-number ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters slot slot-number: Specifies a card by the slot number. If you do not specify a card, this command displays DHCP packet statistics for the active MPU. (In standalone mode.) chassis chassis-number slot slot-number: Specifies a card on an IRF member device or specifies a PEX. The chassis-number argument represents the member ID of the IRF member device or the virtual chassis number of the PEX. The slot-number argument represents the slot number of the card or PEX. If you do not specify a card or PEX, this command displays DHCP packet statistics for the global active MPU. (In IRF mode.) Examples # Display DHCP packet statistics for DHCP snooping. <Sysname> display dhcp snooping packet statistics DHCP packets received : 100 DHCP packets sent : 200 Invalid DHCP packets dropped : 0 Related commands reset dhcp snooping packet statistics display dhcp snooping trustUse display dhcp snooping trust to display information about trusted ports. Syntax display dhcp snooping trust Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Examples # Display information about trusted ports. <Sysname> display dhcp snooping trust DHCP snooping is enabled. Interface Trusted ========================= ============ Ten-GigabitEthernet1/0/1 Trusted Related commands dhcp snooping trust reset dhcp snooping bindingUse reset dhcp snooping binding to clear DHCP snooping entries. Syntax reset dhcp snooping binding { all | ip ip-address [ vlan vlan-id ]} Views User view Predefined user roles network-admin mdc-admin Parameters all: Clears all DHCP snooping entries. ip ip-address: Clears the DHCP snooping entry for the specified IP address. vlan vlan-id: Clears DHCP snooping entries for the specified VLAN. If you do not specify a VLAN, this command clears DHCP snooping entries for the default VLAN. Usage guidelines This command applies to all slots. Examples # Clear all DHCP snooping entries. <Sysname> reset dhcp snooping binding all Related commands display dhcp snooping binding reset dhcp snooping packet statisticsUse reset dhcp snooping packet statistics to clear DHCP packet statistics for DHCP snooping. Syntax In standalone mode: reset dhcp snooping packet statistics [ slot slot-number ] In IRF mode: reset dhcp snooping packet statistics [ chassis chassis-number slot slot-number ] Views User view Predefined user roles network-admin mdc-admin Parameters slot slot-number: Specifies a card by the slot number. If you do not specify a card, this command clears DHCP packet statistics for the active MPU. (In standalone mode.) chassis chassis-number slot slot-number: Specifies a card on an IRF member device or specifies a PEX. The chassis-number argument represents the member ID of the IRF member device or the virtual chassis number of the PEX. The slot-number argument represents the slot number of the card or PEX. If you do not specify a card or PEX, this command clears DHCP packet statistics for the global active MPU. (In IRF mode.) Examples # Clear DHCP packet statistics for DHCP snooping. <Sysname> reset dhcp snooping packet statistics Related commands display dhcp snooping packet statistics BOOTP client commandsdisplay bootp clientUse display bootp client to display information about a BOOTP client. Syntax display bootp client [ interface interface-type interface-number ] Views Any view Predefined user roles network-admin network-operator mdc-admin mdc-operator Parameters interface interface-type interface-number: Specifies an interface by its type and number. If you do not specify an interface, this command displays BOOTP client information on all interfaces. Examples # Display BOOTP client information on VLAN-interface 10. <Sysname> display bootp client interface vlan-interface 10 Vlan-interface10 BOOTP client information: Allocated IP: 169.254.0.2 255.255.0.0 Transaction ID: 0x3d8a7431 MAC Address: 00e0-fc0a-c3ef Table 18 Command output
Related commands ip address bootp-alloc ip address bootp-allocUse ip address bootp-alloc to configure an interface to use BOOTP for IP address acquisition. Use undo ip address bootp-alloc to cancel an interface from using BOOTP. Syntax ip address bootp-alloc undo ip address bootp-alloc Default An interface does not use BOOTP for IP address acquisition. Views Interface view Predefined user roles network-admin mdc-admin Examples # Configure VLAN-interface 10 to use BOOTP for IP address acquisition. <Sysname> system-view [Sysname] interface vlan-interface 10 [Sysname-Vlan-interface10] ip address bootp-alloc Related commands display bootp client Which port does the relay agent use when it sends DHCP information back to the client 68 80 67 53?DHCP messages from a client to a server are sent to the 'DHCP server' port (67), and DHCP messages from a server to a client are sent to the 'DHCP client' port (68).
What port does DHCP relay use?The default port is 67. Select the network interfaces that are used by the DHCP relay agent to connect to the DHCP server and client networks.
What incoming server port does DHCP relay on to receive requests?IPv4 DHCP relay traffic between relay and server is sent as UDP unicasts with source port of 67 and destination port of 67.
How does DHCP work with relay agent?The DHCP client sends a discover packet to find a DHCP server in the network from which to obtain configuration parameters for the subscriber (or DHCP client), including an IP address. The DHCP relay agent receives the discover packet and forwards copies to each of the two DHCP servers.
|