There are many approaches to network troubleshooting. The first is to work up through the layers of the OSI model. This method isolates problems that can masquerade as other problems. You can waste a lot of time troubleshooting a browser that does not function properly, only to find that the computer is not connected to the network. It is best to start troubleshooting at Layer 1. Ask yourself whether things are plugged in and connected before you go to the next higher level, with its more complicated issues. An effective troubleshooting approach by OSI layer is summarized in the graphic.

In this chapter, you learned that:

• the term token-ring refers both, to IBM's token-ring and to IEEEs 802.5 specification
• FDDI has four specifications:

1.       Media Access Control (MAC)

2.       Physical Layer Protocol (PHY)

3.       Physical Layer Medium (PMD)

4.       Station Management (SMT)

• Ethernet and IEEE 802.3 currently maintain the greatest market share of any LAN protocol
• the term Ethernet is often used to refer to all carrier sense multiple access/collision detection (CSMA/CD) LAN’s that generally conform to Ethernet specifications, including IEEE 802.3

Additionally, you learned about Layer 2 devices and their effects on data flow. Finally, you were introduced to basic Ethernet 10BASE-T troubleshooting.  In the next chapter, you will be introduced to network design and documentation.