Chapter17.Frame Relay Troubleshooting

Chapter 17. Frame Relay Troubleshooting

Troubleshooting Frame Relay connections is a design-dependant process, which starts with a clear understanding of the kind of connection you are troubleshooting. You need to know if this is a point-to-point or point-to-multipoint design, if it is a routing or bridging design, if you have a partial-mesh or full-mesh design, if you are using a switched virtual circuit (SVC) or permanent virtual circuit (PVC), how the signaling is maintained, and so on.

The troubleshooting has to be performed as a configurationcontext activity as well. You need to start with the configuration solutions, such as access rate (whether it is 56 kbps or fraction T1), expected bandwidth, committed information rate (CIR) and excess information rate (EIR), and many of the other parameters explained in Chapters 14, "Frame Relay Technology Background," 15, "Frame Relay Design Solutions," and 16, "Basic and Advanced Frame Relay Configurations." You must also make sure that the equipment is properly configured for multicast, compression, and Voice over Frame Relay.

This chapter uses the systematic layer-by-layer approach to troubleshooting that is covered in Chapter 4, "Troubleshooting Approaches, Models, and Tools," and contains physical and data link layer troubleshooting techniques, as follows:

• Physical layer troubleshooting:

  - Line and clocking problems

  - Physical layer-related performance issues

• Data link layer troubleshooting:

  - PVC configuration issues, PVC encapsulation, and bandwidth definition issues

  - Local Management Interface (LMI) issues, including LMI types, messages and keepalives, timers, counters, and code types

• Performance problems:

  - Flapping links and end-to-end problems

  - Troubleshooting Frame Relay shaping problems and congestion control

  - Troubleshooting compression over Frame Relay