December, 2002

You wouldn't believe how many times I have been asked the question "So what exactly is the difference between a switch and a hub anyway?" Or how many times I have heard it answered "Well, switches switch and… err… a hub doesn't." This would leave one to believe that maybe there isn't much difference at all or maybe this is just another one of those marketing strategies so that computer vendors can charge us more. Well that is not the case and there really is a difference (quite a significant one).

Hubs have been around a long time. So long in fact, that many people assume that anything that "connects all their computers together" is a hub. Well, that may not be the case. The term "hub" has become generic for any device that connects computers together. To add to the confusion, there is very little difference in their physical appearance. But on the inside, there is a world of difference.

For those techno weenies out there (like me) that have heard of the OSI model, a switch operates on Layer 2 (or above) of the OSI model and a hub operates at Layer 1. There is NO intelligence to a hub. A hub is literally as though you just meshed all of the copper wires in all the cables from the workstations into one. Everything that one workstation "hears" or transmits all of the others hear. Immediately this may not sound like such a bad idea, but it can have tremendous impact on the performance of your network, especially when you start daisy chaining the hubs together.

The difference with a switch is that once a communications session has been established between two devices (whether computers, network printers or anything else) then none of the other computers or devices can "hear" them. This drastically reduces network traffic.

Now it is necessary to point out here a very common mistake: switches DO NOT block broadcasts. If you don't know what a broadcast is, then you probably can ignore what I am saying. But a broadcast and broadcast "storms" cannot be prevented with a switch (at least not Layer 2 switches).

The good news is that now the cost of a switch is not much more than a hub. In fact, some places don't even sell hubs any more.

Bottom line:

If you're small office / home network has 2-4 computers then you really have no need to upgrade. But if your network has 5+ workstations then it may be worth your investment to purchase a switch.

Now, just before you start thinking this is too simple. There is actually a very wide variety of the types of switches and their brands out there. Look for future articles describing the vendors to stay away from and the features and options you have when purchasing.