DHCPv4 Relay
Enable a Cisco Router to relay a DHCPv4 broadcast messages to a DHCPv4 server
Configuring DHCPv4 Relay
This will cause the Router to relay DHCPv4 broadcasts to the DHCPv4 server
R1(config)# interface g0/0/0 R1(config-if)# ip helper-address 192.168.11.6 R1(config-if)# end R1#
DHCPv4 is not the only service that the router can be configured to relay. By default, the ip helper-address command forwards the following eight UDP services:
- Port 37: Time
- Port 49: TACACS
- Port 53: DNS
- Port 67: DHCP/BOOTP server
- Port 68: DHCP/BOOTP client
- Port 69: TFTP
- Port 137: NetBIOS name service
- Port 138: NetBIOS datagram service