I’ve picked up some Cisco equipment to play around with. Here is my setup:
2 routers connected via a serial link.
The serial interface on Router1 is configured as follows:
ip address 10.0.0.1 255.255.255.252
clock rate 4000000
The serial interface on Router2 is configured as follows:
ip address 10.0.0.2 255.255.255.252
FastEthernet0/0 on Router1 is the default gateway for a laptop I have connected to Router1. The configuration of FastEthernet0/0 is as follows:
ip address 192.168.10.254 255.255.255.0
The routing table on Router1 is as follows:
Gateway of last resort is not set
10.0.0.0/30 is subnetted, 1 subnets
C 10.0.0.0 is directly connected, Serial0/1/0
C 192.168.10.0/24 is directly connected, FastEthernet0/0
The IP configuration on the laptop connected to Router1 is as follows:
IP address = 192.168.10.10
Subnet Mask = 255.255.255.0
Default gateway = 192.168.10.254
From Router1 (10.0.0.1), I can successfully ping Router2 (10.0.0.2).
From the laptop, I can successfully ping the default gateway (192.168.10.254).
From the laptop, I can successfully ping the serial interface on Router1 (10.0.0.1). However, I cannot ping the far side of the point-to-point connection on Router2 (10.0.0.2), and I don’t know why. Router1 obviously knows about the 10.0.0.0 network as it is shown as connected in the routing table. Why can’t I ping 10.0.0.2 from the laptop? Any explanation would be greatly appreciated.