...
Option 82 contains two common sub-options: Circuit ID and Remote ID. Circuit ID is mainly used to identify the VLAN and the interface of the client, Remote ID identifies the device from which the client accessed, usually the MAC address of the device.
Packet Format
Circuit ID Sub-option
Circuit ID includes three types: Type 0 (value is port index), Type 1 (value is port name + VLAN ID) and Type 2 (value is port description + VLAN ID). The format is listed below by types.
...
- DHCP relay configurations must be identical on both VRRP Master/Backup devices, such as the DHCP server address.
- In VRRP topology, DHCP relay only works on the L3 VLAN interface with single VIF, single IP address and single VRID.
- DHCP relay agent address is required in VRRP topology, and it must be specified as the virtual IP address of the VRRP group. The command set protocols dhcp relay interface <vlan-interface-name> relay-agent-address <agent-ipv4-address> can be used to set the DHCP relay agent address. It is used to fill in the giaddr field to identify the client gateway in the DHCP relay Discover/Request/Inform/Release/Decline message where the giaddr is zero. For those DHCP messages in which the giaddr isn’t zero, the giaddr remains unchanged.
- Dynamic ARP Inspection (DAI) is supported in the Active-Active VRRP mode, but NOT supported in the standard VRRP mode.
...