DHCP relaying allows you to share a single DHCP server across logical network segments that are separated by the firewall. The DHCP relay service only forwards DHCP traffic; it does not assign the IP addresses. When configuring DHCP relay, both the port the DHCP server is connected to and all ports the clients are connected to must be added to the DHCP relay interfaces.
Configure the DHCP relay agent
- Go to the NETWORK > DHCP Relay page.
- Select Enable DHCP Relay.
- From the Relay Interfaces list, select the network interfaces that are used by the DHCP relay agent to connect to the DHCP server and client networks. To add the interface, click + after each selection.
- In the DHCP Server IPs field, add the IP addresses of the DHCP servers. Click + after each entry.
- Enter the UDP Port the relay agent is listening on. Default: 67
- Enable Add Agent ID if you want the DHCP relay agent to add an Agent ID (AID) to the transmitted packets. An AID indicates that the data has been relayed.
- Enter the Max. DHCP packet Size in bytes. Default: 1400
- From the Agent ID Relay Policy list, select how your DHCP relay agent handles DHCP packets that are already flagged by an AID from another agent:
- Append – (default) Attach your AID to the existing AID.
- Replace – Replaces the existing AID with your AID.
- Forward – Passes DHCP packets without any modification.
- Discard – Discards DHCP packets that are already flagged by an AID.
- From the Agent ID Mismatch Policy list, select how your DHCP relay agent handles DHCP server replies that do not contain its AID:
- Discard – (default) Discards the DHCP packet.
Forward – Forwards the DHCP packet to the DHCP client.
- Enter the Max. Packet Hop Count to avoid infinite packet loops (default:
- Select Forward Unicast Packets if Bootstrap/BOOTP unicast messages should be forwarded by the DHCP relay.