Using the set dhcp relay agent Command to Enable Option 82 Suboption Support

Note: The set dhcp relay agent command, when used to configure option 82 suboptions is a legacy command, which JunosE Software continues to support to provide backward-compatibility for existing scripts. We recommend that you use the dhcp relay agent sub-option command for new option 82 suboption configurations.

You can use the set dhcp relay agent command to enable support for DHCP relay agent option, which includes the option 82 suboptions—Agent Circuit ID (suboption 1) and Agent Remote ID (suboption 2). This command does not support the Vendor-Specific option (suboption 9).

The suboptions include information from the DHCP relay agent that the DHCP server can use to implement parameter assignment policies. The DHCP server echoes the suboptions when it replies to the client—the DHCP relay agent can optionally strip the option 82 information before relaying the packets to the client. (Use the CLI command set dhcp relay preserve-trusted-client-option to configure this behavior for trusted clients.)

When you issue the set dhcp relay agent command, the router adds the configured DHCP relay agent information suboptions to every packet it relays from a DHCP client to a DHCP server.

The circuit-id-only keyword specifies the Agent Circuit ID suboption, which contains the following information, based on interface type. This keyword disables support for the Agent Remote ID suboption.

• ATM interface
  [<hostname>|<vrname>:]<interface type> <slot>/<port>[.<sub-if>]:<vpi>.<vci>

  Examples:

  atm 4/1.2:0.101relayVr:atm 4/1:0.101bostonHost:atm 4/1.2:0.101

• Ethernet interface
  [<hostname>|<vrname>:]<interface type> <slot>/<port>

  Examples:

  fastEthernet 1/2relayVr:fastEthernet 1/2bostonHost:fastEthernet 1/2

• Ethernet interface with VLAN
  [<hostname>|<vrname>:]<interface type> <slot>/<port>[.<sub-if>]:<vlan id>

  Examples:

  fastEthernet 1/2.3:4relayVr:fastEthernet 1/2:4bostonHost:fastEthernet 1/2.3:4

• Ethernet interface with Stacked VLAN
  [<hostname>|<vrname>:]<interface type> <slot>/<port>[.<sub-if>]:
  <svlan id>-<vlan id>

  Examples:

  fastEthernet 1/2.3:4-5relayVr:fastEthernet 1/2:4-5bostonHost:fastEthernet 1/2.3:4-5

• LAG interface
  [<hostname>|<vrname>:]<interface type> <bundle name>

  Examples:

  lag bundleArelayVr:lag bundleAbostonHost:lag bundleA

• LAG interface with VLAN
  [<hostname>|<vrname>:]<interface type> <bundle name>[.<sub-if>]:<vlan id>

  Examples:

  lag bundleA.1:2relayVr:lag bundleA:2bostonHost:lag bundleA.1:2

• LAG interface with Stacked VLAN
  [<hostname>|<vrname>:]<interface type> <bundle name>[.<sub-if>]:
  <svlan id>-<vlan id>

  Examples:

  lag bundleA.1:2-3relayVr:lag bundleA:2-3bostonHost:lag bundleA.1:2-3

The remote-id-only keyword specifies the Agent Remote ID suboption, which contains a value only when (1) the interface is a dynamic ATM interface and (2) the subscriber command is used to configure a username and domain name for the interface. If both conditions are met, the suboption contains a string with the username and domain name in the format: username@domainname. The remote-id-only keyword disables support for the Agent Circuit ID suboption.

If you do not explicitly specify the circuit-id-only or remote-id-only keyword, both suboptions are used.