3Com 5500 Configuration Procedure # Enable Dhcp, # Enable unauthorized Dhcp server detection

196CHAPTER 21: DHCP CONFIGURATION GUIDE

Applicable Products

Product series	Software version	Hardware version
Switch 5500	Release V03.02.04	All versions
Switch 5500G	Release V03.02.04	All versions

Configuration Procedure # Enable DHCP.

[SwitchA] dhcp enable

#Exclude the IP addresses of the DNS server, WINS server, and gateways from dynamic assignment.

[SwitchA] dhcp server forbidden-ip 10.1.1.2

[SwitchA] dhcp server forbidden-ip 10.1.1.4

[SwitchA] dhcp server forbidden-ip 10.1.1.126

[SwitchA] dhcp server forbidden-ip 10.1.1.254

# Enable unauthorized DHCP server detection.

[SwitchA] dhcp server detect

#Configure the address range, domain name suffix and DNS server address in DHCP address pool 0.

[SwitchA] dhcp server ip-pool 0

[SwitchA-dhcp-pool-0]	network 10.1.1.0 mask 255.255.255.0
[SwitchA-dhcp-pool-0]	domain-name aabbcc.com
[SwitchA-dhcp-pool-0]	dns-list 10.1.1.2
[SwitchA-dhcp-pool-0]	quit

#Configure the address range, gateway address, and lease duration in DHCP address pool 1.

[SwitchA] dhcp server ip-pool 1

[SwitchA-dhcp-pool-1]	network 10.1.1.0 mask 255.255.255.128
[SwitchA-dhcp-pool-1]	gateway-list 10.1.1.126
[SwitchA-dhcp-pool-1]	expired day 10 hour 12
[SwitchA-dhcp-pool-1]	quit

#Configure the address range, lease duration, DNS server address and gateway address in DHCP address pool 2.

[SwitchA] dhcp server ip-pool 2

[SwitchA-dhcp-pool-2] network 10.1.1.128 mask 255.255.255.128

[SwitchA-dhcp-pool-2] expired day 5

[SwitchA-dhcp-pool-2] nbns-list 10.1.1.4

[SwitchA-dhcp-pool-2] gateway-list 10.1.1.254

[SwitchA-dhcp-pool-2] quit

With the unauthorized DHCP server detection enabled, Switch A will log information about all DHCP servers, including authorized ones. The administrator needs to find unauthorized DHCP servers from the system log information. If Switch A detects an unauthorized DHCP server, the following log information is recorded.