Summary

This chapter has introduced some basic troubleshooting techniques and guidelines. The two main ingredients in all network engineers' troubleshooting techniques are as follows:

• Knowledge of the way things are supposed to behave.

• The ability to forget how things are supposed to behave and to have faith that what you are seeing is what is really happening.

The next chapter, which is about bridging IP between different LAN types, seeks to explain a common problem encountered by network engineers attempting to connect different LAN types by bridging. The problem is that in many cases, bridges cannot provide IP connectivity between TCP/IP hosts on different types of LANs. This is because they do not take into account the IP functions occurring at layer three that are needed to establish IP connectivity. Most bridges do not know how to handle these layer three issues because they operate only at layer two (normally the highest layer that bridges are required to understand).