Connecting 2 or more switches on a computer network is a very common functionality. By connecting 2 or more switches together, we gain a larger amount of connectivity and benefits on a network.
One of the first things that occurs from connecting multiple switches together on the same network is that you increase the size of the broadcast domain (more nodes are connected together). You also create a larger physical distance on the network.
There Are 2 Basic Ways…
There are essentially 2 ways to make these connections between switches:
- Uplink ports (whereby you connect the uplink port on one switch to a normal networking port on the other switch using a straight-thru cable)
- Port-to-Port using the normal networking switch ports (typically on the front of the switch) using a cross-over cable
The Different Types of Network Cables
Now, I’d like to point out that if you don’t yet understand the different types of networking cables and their pin layouts inside each type of cable (in this case we’re talking about straight-thru and cross-over), make sure to check out this post and video where I go through the different types of cables and how the internal wires and pins are arranged within each.
1. Using ‘Uplink’ Ports
So let’s take a closer look at the Uplink Port connection between 2 switches. I’ll show you how that works. Then we’ll look more closely at the more commonly used connection method used between 2 switches, the cross-over cable using the normal networking ports (again typically on the front of the switch).
When you use an Uplink port, 9 times out of 10 the manufacturer will clearly mark that port on the physical switch as being the “Uplink”
If you choose to use the uplink port, you will have to use a straight-thru type network cable to connect the other switch using one of its normal network connection ports (these would be the same ports you might connect any other device to that 2nd switch with – printers, desktops, laptops, servers, etc.).
There are several different reasons for using the uplink port on one switch connected to a networking port on the other switch. In my experience, you get some benefits in the way the port can be configured in the switch’s configuration.
Sometimes (again depending on the manufacturer) you can give yourself more “real estate” by freeing up a normal network port on the front of the switch in using the uplink port for connecting to an adjacent switch on the network. You can often change some specific settings for things like spanning tree and management access in the configuration settings for the uplink port that you may not have available on the normal network port.
To daisy-chain multiple switches together using the uplink port method, you will use one uplink port connected to one regular port, then uplink port connected to the next switch’s regular port (just like in this diagram).
If you choose to work with uplink ports on switches, just take your time and watch that the connections are done correctly. I also wanted to point out that switch manufacturers sometimes call the uplink port by a different name or give it a different label – You may see it called “crossover” or MDI-X or OUT.
Also, I feel like this is a really good time to point something else out on network switches. If you see a line on the label connecting the uplink port and another port (like this whereby you have a line running to the 2X port), this more often than not means you can only use one port or the other – you cannot use both ports at the same time.
And last but not least when dealing with uplink ports on switches, some manufacturers will place a button next to the uplink port. This button allows you to change the port from an uplink port to a regular port. When you press the button, it changes the pin layout inside the port to make the port either uplink or regular network port.
2. Normal Networking Ports
This leads us to the other type of connection between switches using regular network port to regular network port using a cross-over cable.
This is actually the more common type of connection used on-the-fly by network technicians, admins and engineers. If you choose to connect 2 switches together using their regular network ports, you have to use a cross-over cable. You cannot use a straight-thru cable. This is because if you inadvertently use a straight-thru cable, both switches will attempt to send their data on the second pair of wires (3 and 6) and will try to listen for data on the first pair (1 and 2). A cross-over cable reverses the pins on each end of the cable. So one end will be wired with the T568A standard and the other end with the T568B standard.
Again, check out this video showing the different types of cable pin layouts.
So when connecting switches together, those are the 2 types of connection you can use.
Now there’s one other thing I wanted to point out here. On most newer Layer 2, Layer 3 and multilayer switches, you will have a feature (and it may be physically marked on next to each port) but you will have a feature called MDI-X. The MDI stands for (media-dependent interface) which is for a regular port on a switch. When you see MDI-X this means it’s capable of being an uplink port.
Most newer switches have a feature called Auto MDI-X which actually senses which type of cable is connected and can change from MDI (regular port) to MDI-X (uplink port) if it needs to – this is more often due to human error. But I’ve seen a lot of technicians just use whatever type of network cable they have available and they rely on the auto MDI-X to make the correct determination. I don’t recommend this, as you need to know what you’re using on your network and how things are connected, but that’s neither here nor there.
In troubleshooting connectivity issues on a network, if the connection isn’t working, one of the first things you look at is the MDI/MDI-X and determining if you’re using the correct cable on the connection and if the cable is good or no.
So those are the basics of connecting switches together! If you like this post, be sure to watch for the next!