When I teach classes on protocol and communications analysis, I often find that the audience is missing one fundamental piece of knowledge--a basic understanding of how data flows through a network. For example, how does a packet get from your workstation to the server on another network? How do the interconnecting devices (such as routers, switches, and hubs) affect the path that the packet takes? How do these devices change the content of the packet? Does the packet travel across any networks unnecessarily?

This article explains how interconnecting devices such as hubs, switches, and routers affect the flow of data on a network. Specifically, this articles explains how each device forwards packets and whether or not it changes packets before forwarding them.

This article is a must read for anyone who works on networks. This article doesn't take long to read, so find a nice spot where no one will bother you for 30 minutes.