DHCP Configuration 3 Points

A number of Windows XP users on VLAN_D support DHCP and the ability to receive more than one IP gateway. Configure R2 to provide only a pool of DHCP addresses with the following criteria:

■ The IP addresses pool ranges from 144.254.4.0/26 shared between R2 and R3.

■ The DNS servers are 139.134.2.2 and 139.134.1.1.

■ Default gateway of 144.254.4.1 or 144.254.4.2 only.

■ Hosts must retain DHCP-assigned addresses forever.

■ The predefined addresses 144.254.4.1, 144.254.4.2, and 144.254.4.3 are never allocated to DHCP clients.

You can assume that you have Windows XP clients only and support more than one gateway if any one router fails.

DHCP Configuration Solution

VLAN_D contains the subnet 144.254.4.0/26 with the allocated IP addresses, one each to R2 E0/0, R3 Fast0/0, and the Catalyst 3550 management interface. You must ensure that any DHCP servers (R2, in this case) do not allocate these three preassigned address.

Example 8-63 configures R2 for DHCP pool allocation.

Example 8-63 DHCP Configuration on R2

ip dhcp excluded-address 144.254.4.1 ip dhcp excluded-address 144.254.4.2 ip dhcp excluded-address 144.254.4.3 !

ip dhcp pool ccie network 144.254.4.0 255.255.255.192

domain-name cisco.com dns-server 139.134.2.2 139.134.1.1

default-router 144.254.4.1 144.254.4.2 lease infinite

R2 provides the DNS domain name and two default gateways. Notice that the lease is enabled to be used forever by DHCP clients with the IOS command lease infinite. If R2 fails, all DHCP clients with existing IP addresses will route through Router R3 with the default gateway 144.254.4.1.

Was this article helpful?

0 0

Post a comment