Cannot ping other lan with xp as router

Case Study - Can't ping other LAN with XP Pro as a router

Environment: A student tries to setup a XP as a router to connect two LANs, 192.168.100.0/24 and 192.168.200.0/24. Here are the configurations:

In 192.168.100.0 LAN1: Windows 2000 Pro with IP 192.168.100.1, Subnet mask 255.255.255.0 and default gateway 192.168.100.254. There is a D-Link router with IP 192.168.100.254 to connect to the Internet.

The XP as router: NIC1: 192.168.100.2/255.255.255.0, DG 192.168.100.254.

NIC2: 192.168.200.2/255.255.255.0, IP routing enabled.

In 192.168.200.0 LAN2: Windows XP Pro with 192.168.200.1, Subnet mask 255.255.255.0 and default gateway 192.168.200.2

Situation: In LAN1, the computer can ping outside web and the XP router. However, it can’t ping any thing in LAN2, no 192.168.200.1 and 192.168.200.2.

In LAN2, the computer can ping public IP, the XP router and 192.168.100.1, 192.168.100.2 and 192.168.100.254. Why can’t he ping LAN2 from LAN1?

Analysis: This is routing issue. So, we print out routing tables from all computers. We found LAN1 computer pointed all traffic to 192.168.100.254. Here is the routing table.

Active Routes:

Network Destination Netmask Gateway Interface Metric

0.0.0.0 0.0.0.0 192.168.100.254 192.168.100.1 1

192.168.100.0 255.255.255.0 192.168.100.1 192.168.100.1 1

192.168.100.1 255.255.255.255 127.0.0.1 127.0.0.1 1

192.255.255.255 255.255.255.255 192.168.100.1 192.168.100.1 1

127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1

224.0.0.0 224.0.0.0 192.168.100.1 192.168.100.1 1

255.255.255.255 255.255.255.255 192.168.100.1 1000003 1

Default Gateway: 192.168.100.254

Resolution: To enable to access LAN2, he needs to add a route on the Windows 2000 computer to point the traffic to 192.168.100.2, in our case, route add 192.168.200.0 mask 255.255.255.0 192.168.100.2.

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