The following example is utilizing two Cisco 2500 series routers with two serial interfaces and two ethernet interfaces. I created a lab Wide Area Network (WAN) in order to configure static routes on Cisco routers. My goal was to create a static route from the ethernet interface (172.16.3.1) on router-1 to reach the ethernet interface (172.16.5.1) on router-2. After creating the static route on the router-1 ethernet interface (172.16.3.0/24) to reach the 172.16.5.0/24 network on the ethernet interface of router-2 I was still unable to ping the 172.16.5.0/24 network from the 172.16.3.0/24 network. I then began troubleshooting.
My first thought was that the network cable could be the cause due to the fact that I had not used it prior. After switching the network cable in question with a known good cable and receiving the same results I was able to rule out the network cable as the cause of the issue.
My next suspicion was that the ethernet interface on router-2 was possibly dead. I knew this was not the case after viewing the results of the “show ip interface brief” command and seeing the interface was up/up.
router-2#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0 172.16.5.1 YES NVRAM up up
Serial0 172.16.4.2 YES NVRAM up up
Serial1 unassigned YES unset administratively down down
My next step in troubleshooting was to view the static route entry I previously created from the 172.16.3.0/24 network to the 172.16.5.0/24 network using the “show running-config” command. I did not use the “show ip route” command because the static route entry would not have shown itself in the routing table due to the fact that the two networks were not communicating (only networks that communicate show up in the routing table). Upon inspecting the static routing entry I realized I made a mistake in the command syntax and created a new static route entry from the 172.16.3.0/24 network on router-1 to the 172.16.5.0/24 network on router-2. Please keep in mind that the two prior networks are configured on the ethernet interfaces of the router and are separated by the WAN (172.16.4.0/24) on the serial0 interfaces of the routers. The new static entry looks like this.
router-1#config t
Enter configuration commands, one per line. End with CNTL/Z.
router-1(config)#ip route 172.16.5.0 255.255.255.0 172.16.4.2 permanent
router-1(config)#^Z
I then verified the route in the routing table.
router-1#show ip route
Codes: C – connected, S – static, I – IGRP, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP
i – IS-IS, L1 – IS-IS level-1, L2 – IS-IS level-2, * – candidate default
U – per-user static route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 3 subnets
C 172.16.4.0 is directly connected, Serial0
S 172.16.5.0 [1/0] via 172.16.4.2
C 172.16.3.0 is directly connected, Ethernet0
I tested the entry using the “ping” command from router-1.
router-1#ping 172.16.5.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 172.16.5.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
router-1#ping 172.16.5.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 172.16.5.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
The Internet Protocol (IP) address of 172.16.5.1 is the default gateway of the 172.16.5.0/24 network and the IP address of 172.16.5.2 is the host on the network. As you can see from the output above this static route entry was entered correctly and is functioning properly.
Enjoy!