Now that we’ve covered routers and switches, let’s turn to the third piece of network hardware you might encounter in the wild — a hub. To be clear, hubs are actually pretty rare these days. Modern network companies don’t build them anymore. There’s a reason for this: Hubs are the simplest and slowest method of extending a home or small business network.
Routers, as we’ve previously explained, perform a number of sophisticated routing functions, and are capable of simultaneously managing both wired and wireless connections, as well as providing a firewall and basic security functionality. Switches are less complex than routers and typically only provide wired Ethernet ports, but can direct traffic to each individual computer. This last capability is critical — it’s the difference between a switch and a hub.
Delivering the Mail:
Let’s assume we have four computers, each with its own IP address. An IP address is like your home address — it tells the router or switch how to send packets (or mail, to extend our physical analogy) to your system, not your neighbor’s. A switch knows how to drive traffic to each individual system. A hub doesn’t.
This is where the physical analogy breaks down a bit. Imagine that your mailman had no idea who lived in which apartment in a building, or each house on a street – so his solution was to photocopy everyone’s mail and give everyone a copy of everything. Not only would this be incredibly frustrating, it would impose a substantial burden on each individual person. The CPU/spouse/increasingly angry homeowner would have to sort through each and every packet of information, searching for the ones that belong to him or her.
This system also scales extremely poorly. If there are two or three computers connected to the hub, they can handle the additional sorting. Plug 20 computers into a hub, and every system is sorting through 19 other sets of incorrect information to find their own data. Furthermore, this puts a huge burden on our hypothetical postman, who has to sustain traffic to all 20 connections (meaning, photocopy and distribute 20 sets of mail). Eventually, whatever speed he gained by refusing to sort the mail will be completely consumed by the work of hauling it around and blasting it out.
Why would anyone build such a flawed system in the first place? A few decades ago, it made sense to separate the functions of a switch compared with those of a hub. Today’s computers transfer far more bandwidth across home networks. Before the rise of Facebook, YouTube, and Netflix, there wasn’t much traffic flowing across the Internet. If you were using AOL Instant Messenger and answering a few emails, it didn’t matter so much if your packets were duplicated. Since not many people owned more than two computers in a home, it also didn’t matter if the port duplication hardware was rather, well, stupid.
Today, on the modern Internet, it can matter a great deal — and advances in circuit design and function have obviated the once-substantial price difference that separated hubs and switches. With the cost savings gone and bandwidth needs skyrocketing, putting a hub on a modern network would substantially impair its performance.
The upshot of all this is that you’re unlikely to encounter a hub out in the wild. But if you do encounter one, or happen to be using one yourself, we’d recommend replacing it. A simple switch is fine – even a low-cost switch will offer vastly improved performance compared with an older hub.
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