Troubleshooting A Dhcp Server - 3Com E4500-24 Cli Configuration Manual

[Sysname] interface vlan-interface 3
[Sysname-Vlan-interface3] ip address 10.1.2.1 24
[Sysname-Vlan-interface3] quit
# Create a domain and a RADIUS scheme. Associate the domain with the RADIUS scheme.
[Sysname] radius scheme 123
[Sysname-radius-123] primary authentication 10.1.2.2
[Sysname-radius-123] primary accounting 10.1.2.2
[Sysname] domain 123
[Sysname-isp-123] scheme radius-scheme 123
[Sysname-isp-123] quit
# Create an address pool on the DHCP server.
[Sysname] dhcp server ip-pool test
[Sysname-dhcp-pool-test] network 10.1.1.0 mask 255.255.255.0
# Enable DHCP accounting.
[Sysname-dhcp-pool-test] accounting domain 123

Troubleshooting a DHCP Server

Symptom
The IP address dynamically assigned by a DHCP server to a client conflicts with the IP address of
another host.
Analysis
With DHCP enabled, IP address conflicts are usually caused by IP addresses that are manually
configured on hosts.
Solution
Disconnect the DHCP client from the network and then check whether there is a host using the
conflicting IP address by performing ping operation on another host on the network, with the
conflicting IP address as the destination and an enough timeout time.
The IP address is manually configured on a host if you receive a response packet of the ping
operation. You can then disable the IP address from being dynamically assigned by using the dhcp
server forbidden-ip command on the DHCP server.
Attach the DHCP client to the network, release the dynamically assigned IP address and obtain an
IP address again. For example, enter DOS by executing the cmd command in Windows XP, and
then release the IP address by executing the ipconfig/release command. Then obtain an IP
address again by executing the ipconfig/renew command.
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