Chapter Summary

In this chapter you learned the tools and commands you can use to make sure your Physical layer functions and performs properly. The router's interfaces and controllers are among your first troubleshooting targets. These router interfaces and controllers both continuously collect and store information on their performance and status.

Physical devices including TDRs, OTDRs, and cable testers can be used to test the physical cabling. This can help you determine whether connectivity issues are a result of faulty cabling or installations.

CDP can be use to see what devices the Cisco router or switch believes are directly connected. The show cdp command provides information as to the directly connected Cisco devices' platform, IOS version, connected ports, host names , and other important information.

NMS software and devices can be used to make monitoring the physical devices in your network easier. This can make diagnosing problems in your network quicker and easier. A number of software packages were discussed such as CiscoWorks, CWSI, Cisco Netsys, and Cisco View.

Also discussed in this chapter were protocol analyzers that are better known as network sniffers. These can be used to capture and take statistics of the data traffic traversing the physical network.

This chapter also discussed the Physical layer troubleshooting commands and their output. For the exam, it is important that you understand the Physical layer troubleshooting commands, when to use those commands, and how to interpret each command's output.