Content

| Summary

This module examined troubleshooting techniques and common problems associated with the following Layer 2 protocols and technologies:

- Switches and switched technologies
- PPP
- ISDN
- Frame Relay

The difficulty in troubleshooting these technologies is the inability of common Layer 3 troubleshooting tools, such as ping, to assist with anything but the identification that the network is down. It is only through a thorough understanding of the protocols and their operation that a network technician will be able to choose the appropriate troubleshooting methodology and IOS commands to solve the problem in an efficient manner.

In the case of switched networks, it is quite possible to design a functional but suboptimal network. With no apparent network failure, it will only be the awareness of common problems and the ability of a network technician to identify Layer 2 traffic paths that will allow the network technician to achieve the full performance a network is capable of.

After completing this module, the students should be confident that they can recognize common Layer 2 problems and address them quickly and accurately