3Com Switch 7750 Configuration Guide Guide

Troubleshooting DHCP Relay 585
Network diagram
Figure 148 Network diagram for DHCP relay
Configuration procedure
# Enter system view.
<SW7750> system-view
# Enable DHCP.
[SW7750] dhcp enable
# Create DHCP server group 1 and configure an IP address of 202.38.1.2 for it.
[SW7750] dhcp-server 1 ip 202.38.1.2
# Map VLAN 2 interface to DHCP server group 1.
[SW7750] interface Vlan-interface 2
[SW7750-Vlan-interface2] dhcp-server 1
# Configure an IP address for VLAN 2 interface, so that this interface is on the
same network segment with the DHCP clients.)
[SW7750-Vlan-interface2] ip address 10.110.1.1 255.255.0.0
n
You need to perform corresponding configurations on the DHCP server to enable
the DHCP clients to obtain IP addresses from the DHCP server. The DHCP server
configurations vary with different DHCP server devices, so the configurations are
omitted.
Troubleshooting DHCP
Relay
Symptom
A client fails to obtain configuration information through a DHCP relay.
Analysis
This problem may be caused by improper DHCP relay configuration. When a DHCP
relay operates improperly, you can locate the problem by enabling debugging and
checking the information about debugging and interface state (You can display
the information by executing the corresponding display command.)
Ethernet
Ethernet
Internet
DHCP client
DHCP client
Switch ( DHCP Relay )
10.110.0.0
DHCP Server
202.38.1.2
10.110.1.1
202.38.1.0
202.38.1.1
Ethernet
Ethernet
Internet
DHCP client
DHCP client
Switch ( DHCP Relay )
10.110.0.0
DHCP Server
202.38.1.2
10.110.1.1
202.38.1.1
Ethernet
Ethernet
Internet
DHCP client
DHCP client
Switch ( DHCP Relay )
10.110.0.0
DHCP Server
202.38.1.2
10.110.1.1
202.38.1.0
202.38.1.1
Ethernet
Ethernet
Internet
DHCP client
DHCP client
Switch ( DHCP Relay )
10.110.0.0
DHCP Server
202.38.1.2
10.110.1.1
202.38.1.1