There’s an article up on SecurityFocus called “Basic journey of a packet”. It gets into some of the details of TCP/IP and routing, and should prove a useful introduction to those not fully on what’s happening behind the scenes. From the article:
Once an Internet application is invoked, a whole series of events takes place. This article will be a simple introduction to how a packet is created and the various devices it will travel through on the way to its destination. Having an understanding of just what happens between point A and point Z can be quite helpful in furthering your understanding of networking.
I think the article gives a good sense of how incredibly complex networking really is. At each layer from the physical to application there’s an incredible amount of work going on, just to simply view a webpage. Networking is a good example of how powerful layers of abstraction can be. Each stage builds upon the last, while still creating an simpler interface for the next. It creates a sort of stack, with each stage being simpler and easier to use. At the bottom you have the physical layer, which would require a good deal of knowledge of physics and electronics to begin to comprehend. Yet once you get to the top you’re dealing with something as simple as typing “www.google.com” into your browser and hitting go. Much of the technology we take for granted today works because of these kinds of abstractions.
The article also mentions the differences between networking and programming. I think for both network administrators and programmers it’s very useful to have at least a passing understanding of what’s happening at each stage, each layer of abstraction. Whether you’re fixing a network problem or debugging a web application, you never know if you might be working with an application error or a broken ethernet link.
