Prajith

There are several things that would produce the line up line protocol down condition on a serial interface. Things that you should check include:

- problems with clocking can produce the protocol down. What is providing clock for the serial link?

- mismatched protocols can cause the protocol down condition. If one end is PPP and the other end is HDLC (or Frame Relay) it would produce the protocol down condition.

- if the serial link uses Frame Relay encapsulation and if the interface specifies an LMI type that does not match the provider Frame Relay switch LMI type it would produce the protocol down condition.

- if the serial interface on one router is configured with normal keepalives and the serial interface on the other router is configured with no keepalives it would produce the protocol down condition.

Check these things and let us know if any of them were causing your problem.

HTH

Rick