Configure the DHCPv4 Relay

You can configure the DHCPv4 relay feature on any Layer 3 interface, such as a switch front-end Ethernet interface (VE port) or a physical interface.

About this task

The DHCPv4 relay feature allows forwarding of requests and replies between DHCP servers and clients connected to the switch when these servers and clients are not on the same subnet.

Consider the following when you configure the IP DHCP relay agent:

You can configure up to 16 DHCP server IP addresses per interface. When multiple addresses are configured, the relay agent relays the packets to all server addresses. The total number of addresses configurable on the router is 4000.
The DHCP server and the clients it communicates with can be attached to different VRF instances. For more information, see VRF Support in DHCPv4.

Procedure

Access global configuration mode.
```
device# configure
```
Access interface configuration mode.
```
device(config)# interface ethernet 1/18
```
Identify the DHCP server to which DHCP client requests are to be forwarded.
1. If the DHCP server and its clients are attached to the same VRF instance, use the following syntax.
```
device(config-if-eth-1/18)# ip dhcp relay address 100.1.1.2
```
2. If the DHCP server and its clients are on different VRF instances, use the following syntax.
```
(config)# int ve 100
device(config-ve-100)# ip dhcp relay 100.1.1.2 use-vrf blue
```

Example

This example removes a relay address.

device(config-if)# no ip dhcp relay address 200.1.1.2

Example

This example removes a relay address when the DHCP server is on a different VRF instance.

device(config-ve-103)# no ip dhcp relay address 10.1.2.255 use-vrf blue