Summary

Layer 2 WAN issues boil down to some pretty basic troubleshooting. Interfaces and controllers are the main targets. For example, if serial x is down and the line protocol is down, check the following:

  • Cable

  • Interface

  • CSU/DSU

  • Service provider issues

If serial x is up and the line protocol is down, check the following:

  • Clocking and DTE/DCE cable/interface

  • Encapsulation

  • LMI type

  • Other Frame Relay configuration

  • Loopback tests

  • Service provider issues

Frame Relay is a Layer 2 edge technology that is economic, scalable, manageable, and optimal for the public or private WAN. Connections are through virtual circuits. The entire path is known up front (PVC), and the big advantage to this is not having to set up and tear down the circuits. Unlike its predecessor, ...

Get CCNP Practical Studies: Troubleshooting now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial