Troubleshooting A Dhcp Server - H3C S7500 Series Operation Manual

Operation Manual – DHCP
H3C S7500 Series Ethernet Switches
# Configure DHCP address pool 2, including address range, gateway, WINS server
address, and lease time.
[H3C] dhcp server ip-pool 2
[H3C-dhcp-pool-2] network 10.1.1.128 mask 255.255.255.128
[H3C-dhcp-pool-2] expired day 5
[H3C-dhcp-pool-2] nbns-list 10.1.1.4
[H3C-dhcp-pool-2] gateway-list 10.1.1.254

2.7 Troubleshooting a DHCP Server

I. Symptom
The IP address dynamically assigned by a DHCP server to a client conflicts with the
IP address of another host.
II. Analysis
With DHCP enabled, IP address conflicts are usually caused by IP addresses that are
manually configured on hosts.
III. 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.
Chapter 2 DHCP Server Configuration
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