When enabling DHCP/BOOTP relay and forwarding local UDP broadcasts to a new destination address that is located on a different VRF or the global router, the destination VRF or the global router must be specified in the ip helper-address command. The vrf vrf-name and global parameters have been added to the ip helper-address command.
When forwarding the local UDP broadcasts from a VRF to a destination address on the global router or a different VRF, the DHCP relay agent must include information about itself in order for the DHCP server to determine which pool of client addresses to pull the lease from. Including Option 82 in the DHCP relay information provides the required DHCP relay information.
Use the ip dhcp relay information option vpn command to include DHCP relay agent information in the packet sent to the DHCP server by the client.
The following example:
System(su)->router Alpha-Group System(su-*ha-Group)->configure System(su-*ha-Group-config)->ip forward-protocol udp System(su-*ha-Group-config)->interface vlan.0.10 System(su-*ha-Group-config-intf-vlan.0.10)->ip helper-address 134.141.95.105 vrf Internet-Access System(su-*ha-Group-config-intf-vlan.0.10)->exit System(su-*ha-Group-config)->ip dhcp relay information option vpn System(su-*ha-Group-config)->