Successful troubleshooting relies on three main pillars: logical thinking, technical understanding, and experience with tools, and this series of articles on TCP/IP troubleshooting is firmly based on these pillars. For example, in my first article of this series, we outlined a structured approach that shows how to logically troubleshoot TCP/IP networking problems on Windows-based networks--logical thinking. Then in my second article we examined how routing tables work on Windows computers--technical understanding. In this article we'll gain understanding of how the Repair feature works for repairing common problems with network connections--experience with tools. Future articles will continue to touch each of these three bases (logical thinking, technical understanding, and experience with tools) in turn so you can hone your skills as a troubleshooter.

The Repair feature is a powerful tool that is seldom used because it is not well understood. Accessing this feature is easy--just right-click on a network connection in your Networking Connections folder (or on a connection icon in your system notification area) and select Repair from the shortcut menu. When you do this, a dialog box opens and a series of messages appear showing the progress of the repair actions being taken. What happens under the hood here is that a series of command-line actions are being performed, and each progress message displayed indicates one of these actions has been performed. Let's examine each of these steps that take place when you use Repair to understand what they do and why they are performed.

In the first article of this series, I outlined a structured approach for troubleshooting TCP/IP networking issues on Windows-based networks. Key to this structured approach were three things:

• Understanding the networking technologies and protocols that underlie the problem.
• Determining the different elements of the problem and their attributes.
• Determining which troubleshooting steps and tools should be applied to resolve the problem.

I displayed these items as a bullet list instead of a numbered list because network troubleshooting generally isn't as easy as 1-2-3. In other words, it's often more of an art (i.e. based on intuition) than a science (based on a methodology).

This article gives a high level overview of the routing protocols, and how they fit into our online lives.

Tthe TCP/IP protocol suite. All of those protocols are routed ones, but what are they in turn routed by? Read on to get a high level overview of the routing protocols, and how they fit into our online lives.

The routed vs. the routing

There has always been a great attraction for me to the networking protocols. I don’t know why I have always been fascinated by them, but they do interest me greatly. A good deal of my time has been spent studying and playing with the protocols contained in the TCP/IP protocol suite. What all those protocols have in common is that they are routed protocols. This begs the question of what routes them? A very good question indeed, and one that a great many books have been written about.

What I shall cover in this article is a breakdown of what routing protocols are. How they work, and what kinds of routing protocols there are. Things I won’t be covering are the Cisco IOS syntax used when configuring these routing protocols. Quite a few excellent books out there already do an admirable job of doing just that. Instead, as mentioned, I will concentrate on giving you a high level overview of what routing protocols are, the various types, and what it is that they do.

This is the first of a series of articles on TCP/IP troubleshooting, and future articles will focus on key issues highlighted in this article.

What do you think of when you hear the phrase "TCP/IP troubleshooting"? People who are visually imaginative may see a flowchart. More linear-minded types may see a series of numbered steps. Others (far too common) may feel a sense of inadequacy and frustration.

TCP/IP troubleshooting should be simple, right? After all, it's just a protocol—a series of steps to transfer bits over the network. But what a protocol—four layers, and multiple protocols at each layer.