3com 3031 Instruccion De Instalación

forwarding DHCP messages, so that DHCP client can request configuration 
information (for example IP address) successfully from DHCP server. 

DHCP server is configured with an IP address pool whose segment is 10.110.0.0, 
so the IP addresses can be allocated to the DHCP clients on this segment. DHCP 
server is also configured with routes to the segment 10.110.0.0. 

Figure 106   DHCP relay configuration

1 Configurations on the router: 

a Enable DHCP services

[3Com]dhcp enable

b Enter an interface where DHCP relay function has been enabled, configure IP 

address and mask for it, and ensure that the interface and DHCP client are in 
the same segment.

[3Com]interface ethernet 6/0/0

[3Com-Ethernet6/0/0]ip address 10.110.1.1 255.255.0.0

c Activate DHCP relay services

[3Com-Ethernet6/0/0]dhcp select relay

d Configure IP relay address for the interface to specify the target DHCP server. 

[3Com-Ethernet6/0/0]ip relay address 202.38.1.2

Configurations on DHCP server will not be mentioned here. 

Two types of DHCP client configurations are mentioned here: one is that the 
Ethernet gets dynamic IP address, the other is that the Ethernet sub-interface gets 
dynamic IP address (supporting VLAN). 

1 Networking requirements

The interfaces Ethernet0/0/0 and Ethernet2/0/0 of the router RTA are connected 
respectively into LAN1 and LAN2, which are respectively configured with DHCP 
server 1 and DHCP server 2. The segment for LAN1 is 169.254.0.0/16 and that for 
LAN2 is 172.10.0.0/16. The configuration task is to make the two interfaces get IP 
addresses through DHCP. 

Ethernet

Ethernet

IP Network

DHCP client

DHCP client

DHCP Relay

10.110.0.0

DHCP Server

202.38.1.2

10.110.1.1

202.38.0.0

202.38.1.1