How do you get a serial interface and line protocol to be up on a cisco router?

Question

I have two cisco routers connected with serial cables and they are being configured with a console cable. I set the ip address of both routers 192.168.1.1 255.255.255.0 192.168.2.1 255.255.255.0 and then run a no shut. I exit to exec mode and run a show interface and all I get is Serial is up, line protocol is down. How do I get the line protocol to also be up?

Answer 1

Your IP address are in a different address range. The address you need are:

192.168.1.1 255.255.255.0 and on the other is, 192.168.1.2 255.255.255.0
That makes 256 - 2 = 254 hosts in this range.

Remember a class A is net.host.host.host
class B is net.net.host.host
class C is net.net.net.host

Answer 2

Make sure that one side of the cable is DTE while the other side is DCE.

Add the following command to the serial interface of both routers: 'encapsulation ppp'

Next, configure the clock speed on the router connected to the DCE end of the cable. 'clock rate 64000' Note that the speed can be adjusted...

Answer 3

The previous answer is correct, but is not enough to cause the problem that you're seeing. More likely, there is a physical layer problem between the two interfaces. "debug serial" may well give you the help that you're looking for.