Forwarding Local UDP Broadcasts To A Different VRF (S-, K-Series)

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:

• Enables IP forwarding for the UPD protocol on VRF Alpha-Group
• Enables DHCP/BOOTP relay on VLAN 10 of VRF Alpha-Group and sets the new destination address to 134.141.95.105 on VRF Internet-Access
• Configures the inclusion of DHCP relay agent information in the packet sent to the DHCP server by the client

  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)->