IPv4 DHCP RELAY

IPv4 DHCP relay agent provides a method of relaying/forwarding DHCP and BOOTP requests from a DHCP client and DHCP server on different IP networks. It acts as an interface between DHCP client and the server. The DHCP Relay Agent listens for DHCPv4 or DHCPv6 queries from clients or other relay agents on one or more interfaces, passing them along to upstream servers. When a reply is received from upstream, it is multicast or unicast back downstream to the source of the original request. This page explains about configuring DHCP Relay in zWAN CPE for IPv4.

The DHCP relay service allows you to pass DHCP broadcast messages to network segments that a client computer is not directly attached to. DHCP relaying can be used to share a single DHCP server across logical network segments that are separated by a firewall. The DHCP relay service does not handle IP addresses. It sends unicast messages instead of broadcast messages.

Network Topology

Pre-requisite

DHCP server config should be disabled/deleted on interfaces which are to be added as part of DHCP relay configuration.

Functionality

The zWAN CPE can be configured for DHCP relay by adding the DHCP server IP and the relay interfaces in the zWAN CPE.

Parameters

• Config Name: Configuration Name for reference
• Config Status: Configuration Status to enable the specific relay server config
• Server IP: IP addresses of the DHCP server
• Relay interfaces: Network interfaces that are used by the DHCP relay agent to connect to the DHCP server and client networks. Minimum 2 interfaces required.

Advanced Options

• Port: Default is 67 (Optional)
• Max Packet Size: Default 1400 Bytes (Optional)
• Add AgentID: Append an Agent ID field (Optional)
• Relay AIDPolicy: Default is ‘append’ (Optional)
• Drop Reply AID Mismatch Policy: Drop packets from upstream servers if mismatch occurs (Optional)
• Packet HopCount: Default is 10, Max is 255 (Optional)
• RFC 3527 Compliance and Gateway Interface: Enables RFC 3527 compliance (Optional)

Functionalities in UI

• • Add V4 Relay configuration

• • Edit V4 Relay configuration

• • Delete V4 Relay configuration

• • List V4 Relay configuration

• • Display Config Info

Use Case

Network Topology of DHCP Relay from Branch to DC where separate DHCP server is running behind DC

References

• Barracuda Campus
• Netgate pfSense Documentation
• NVIDIA Cumulus Linux