So, you've read our guide to switches vs routers, and you've decided that it's time to buy a switch. Before you rush out to buy a device, there are some things to think about. Not all switches are equal, and you'll need to understand some things about your network usage before committing to one.
One of the first things to understand about your network is the number of devices on it. Remember that devices and users aren't the same, and you will probably need to connect multiple devices for each employee. Allocate extra network ports for devices including printers, IP surveillance cameras, and wireless access points that need their own wired connection so that they can relay traffic to the internal LAN.
Second, consider the role of the switch. The most common kind is an access switch that connects your users to the network. If your local area network (LAN) supports more than around 50 users, it might be better to invest in several of these. They could connect in turn to a higher-speed core or distribution switch (a kind of 'switch for switches') that connects your access switches to the backbone of your network).
The role of your switch will also determine the layer of the network stack that you want your switch to operate at. Many access switches operate at layer two, which is only interested in the Ethernet (MAC) addresses of your connected devices and is fine for handling internal LAN traffic. A layer three switch takes IP addresses into account. This enables it to separate traffic into virtual LANS (VLANS) that keep groups of computers separate from each other on your network, making it perfect for a core or distribution switch that co-ordinates traffic between access switches.
The third consideration is whether to buy a managed or an unmanaged switch. An unmanaged switch is largely a fire-and-forget network tool. You run cables from your devices into its ports, and the switch takes care of everything else, managing things like data rates and whether to use half-duplex or full-duplex networking. If you're in a small office with no demanding network applications, these are for you.
If you want extra control over your network, then you'll buy a managed switch. These are more expensive network devices that offer you the chance to tinker with your connections. They'll usually come with a built-in interface that you can access in your web browser, so that you can configure a range of options. You'll be able to set different quality of service (QoS) levels for VLANs in your network, so that two computers that need to exchange lots of data quickly get priority, for example. You can often limit bandwidth rates for specific devices so that Colin in accounts can't annoy the office by watching the footy in ultra-high definition on YouTube in his lunch hour.
Fourth, think about the speed of your switch. Luckily, this is a pretty easy consideration. Most switches today support communications at 1000 Mbit/sec (Gigabit) speeds, but you'll still find some with ports limited to a fraction of that, at 10/100 Mbit speeds. You choice here depends on how modern and fast the connected devices on the network are, but we'll assume that unless you're running some painfully ancient kit, Gigabit switches are the way to go for your access switch layer. If you're connecting Wi-Fi access points to your switch this is your only realistic option, as they will aggregate traffic from several devices concurrently. Depending on the size of your network, your core switch could be faster, operating at up to 10 Gbit/sec.
Finally, consider the price of your switch. New core or distribution switches can set you back thousands depending on the features, while you can pick up access switches far cheaper depending on properties such as whether they're managed or not. Understanding the price per connection and factoring in your projected capacity growth and what you expect to do with your network in the future will help you build a switching architecture with the right amount of muscle without overbilling. Your network - and your users - will thank you.