3Com Switch 8800 Advanced Software V5 Configuration Guide

Troubleshooting DHCP Relay Agent Configuration 743

# Enable the DHCP relay agent on Vlan-interface1.

[Sysname] interface vlan-interface 1

[Sysname-Vlan-interface1] dhcp select relay

[Sysname-Vlan-interface1] quit

# Configure DHCP server group 1 with the DHCP server 10.1.1.1, and correlate

the DHCP server group 1 with Vlan-interface1.

[Sysname] dhcp relay server-group 1 ip 10.1.1.1

[Sysname] interface vlan-interface 1

[Sysname-Vlan-interface1] dhcp relay server-select 1

■ Performing the configuration on the DHCP server is also required to guarantee

the client-server communication via the relay agent. Since the DHCP server

configuration varies with devices, it is not mentioned here.

■ If the DHCP relay agent and server are on different subnets, routes in between

must be reachable.

Troubleshooting DHCP

Relay Agent

Configuration

Symptom

DHCP clients cannot obtain any configuration parameters via the DHCP relay

agent.

Analysis

Some problems may occur with the DHCP relay agent or server configuration.

Enable debugging and execute the display command on the DHCP relay agent to

view the debugging information and interface state information for locating the

problem.

Solution

Check that:

■ The DHCP is enabled on the DHCP server and relay agent.

■ The address pool on the same subnet where DHCP clients reside is available on

the DHCP server.

■ The routes between the DHCP server and DHCP relay agent are reachable.

■ The relay agent interface connected to DHCP clients is correlated with correct

DHCP server group and IP addresses for the group members are correct.