Network administrators work with many different types of copper cables. In this video, you’ll learn about cable categories, coax, twinax, and 568A and 568B termination standards.
Copper cabling is the foundation of our Ethernet networks. If you have a network at home, you’re usually connecting with copper Ethernet cable. Whenever we’re building out new networks, we need to make sure that we’re using the correct type of cable for the type of network that we’re installing. And of course, anything that we’re plugging into our network, whether it is a copper wired network or a wireless access point will ultimately come back to that wired connection.
If you were to look inside any of our twisted pair Ethernet cables, you would see four pairs of wires. And you would see that the pairs are twisted around each other. These wires are sending equal and opposite signals down both sides of the wires. You’ll sometimes see this referred to as transmit+ and transmit- or receive+ and receive-.
The reason for sending these opposite signals down the same wires is that we’re taking advantage of the twist, because the wire is twisted, it’s always moving away from any noise or interference that may be occurring anywhere close to the cable. This allows us to compare those signals on the other end, reconstruct what may have been damaged or interfered with during the transmission, and be able to properly receive the total signal.
You’ll also notice that the different pairs have different twist rates, which is another way that we could use to be able to reconstruct that signal on the other side. There are different ways to construct twisted pair cabling using different types of cables and different ways to manufacture the cable itself. These different characteristics of cables are called categories of cables. And we use these categories to determine what type of cable we would use for a different type of network.
For example, if you’re using 1000BASE-T, the IEEE 802.3 standard tells us that we could use category 5 cables to be able to send this gigabit Ethernet connection to a maximum distance of 100 meters. This category 5 cable is a type of category we no longer use. We’ve updated that category to category 5e. The E is for enhanced.
So when you see 1000BASE-T being used, we’re using a minimum of category 5e these days to be able to go 100 meters. But if you happen to have some older category 5 that’s still in the wall and you would like to send 1000BASE-T signal over it, it’ll work great up to 100 meters in length.
If you’re running 10 gig Ethernet, that’s 10GBASE-T, you need a minimum of category 6. If you’re using unshielded twisted pair cable, that supports up to 55 meters in length. And shielded cable will support 100 meters in length. If you’re using category 6A– the A means augmented– you can still run 10GBASE-T to a distance of 100 meters. And if you have category 7– this is a shielded type of cable– it will use 10GBASE-T for that 10 gigabit Ethernet up to a 100 meter distance as well.
And if your requirements are for 40 gigabit Ethernet using the 40GBASE-T standard, then you want to use category 8, which is a shielded cable. And its maximum supported distance is 30 meters.
Not all cable connections are twisted pairs. Sometimes you may be using coaxial cable. Coaxial means that you have two or more forms using the same access. And in this case, it is a single wire conductor that’s used in this particular coax cable. This is commonly the coax cable we would use for cable modem connectivity, for example.
If you look at the coax that’s used inside of your home, you can look on the outside of the cable. And it’s probably labeled to be an RG-6 or a similar type of coax. This is what we normally use for television, our digital cable connectivity, and for our digital internet connections. This is the type of cable you would commonly use for television and for your cable modem connections.
Twinax is similar to coax, except instead of having one single conductor inside the cable, there are two separate conductors, the twins in the twinax. This is the type of cable you would commonly see associated with 10 gig Ethernet over copper, specifically using SFP transceivers. This allows for full duplex connection, because you do have two connections– one for send and one for receive. But it does have a limited distance when used with 10 gig Ethernet. It has a distance of about 5 meters in length.
But because it is coax, it is a copper cable and has a relatively low cost when you compare it to fiber connectivity, especially fiber connectivity on the devices. This is also a very efficient copper cable connection with a lower latency than twisted pair cabling.
One of the things you’ll notice if you go from place to place or company to company is that all of their structured cabling, all of their Ethernet wires, and everything that’s connected inside of their network is identical from location to location. This is by design. There are a set of standards that dictate exactly how you should install and use these twisted pair and copper cable connections. These are the international ISO/IEC 11801 cabling standards.
Inside of North America, you would commonly see the Telecommunications Industry Association standards, or the TIA standards, specifically the ANSI/TIA-568 standard, which is the commercial building telecommunications cabling standard. If you want more information on the TIA, you can find it on their website at tiaonline.org.
The TIA-568 standard is extensive. But for the purposes of what we’ll talk about in this video, we’re going to talk about the standards associated with pin and pair assignments of eight-conductor 100-ohm balanced twisted pair cabling. This is the cable we often use when we’re using Ethernet networks. Specifically, we’re going to talk about two types of standards, the T568A and the T568B.
These 568A and 568B standards dictate what type of colors of cables we will use when punching down these Ethernet connections. The T568A standard has a different set of colors than the T568B standard. But by using either the A or the B standard, we can be assured that we’re matching an A or B standard that’s used anywhere else almost universally.
The standard itself mentions times when you may want to use T568A colors and T568B colors. For example, it mentions that if you’re using horizontal cabling, you would probably use T568A. But many organizations use 568B. Normally, an organization would pick which standard they’re going to follow, and then they use that for their entire infrastructure.
So if you’re walking into an organization and you’re wondering which standard to follow, you simply ask somebody, what do you use here? Do you use 568A or 568B, or you can look at their existing cables and see what colors they’re currently using. There are differences between the T568A and the T568B.
So it’s important that you punch down or use the same standard on both ends of the cable. You don’t want to use T568A on one side and 568B on the other. That creates a lot of confusion. And you may find that the cable is not working as expected.
You may find some documentation that tries to compare the 568A or B standard with Ethernet crossover cables. But the 568A or B standard is not related to Ethernet crossover. Crossover cables are defined in the IEEE 802.3 standard, and not in the 568 standard. We’ll go through crossover cables and how this applies to the colors used in crossover cables in a later video.
Here are the colors used for these two standards. We’re specifically looking at these colors based on the eight wires that are inside of an RJ45 connection. And you can see they’re numbered numbers 1 through 8. For the T568A and 568B, you can see that some of the wires are different, but some are the same. For example, pins 4 and 5 are blue and white and blue in both standards, and pins 7 and 8 are white and brown, and brown in both standards.
The only two pair that are different between the standards are pins 1 and 1 and pins 3 and 6. You can see in 568A pins 1 and 2 are white and green and green, and pins 3 and 6 are white and orange and orange. In the T568B standard, those colors are simply reversed.
One way to tell what standard is being used in a particular cable is to look very closely at the colors that are along the outside. And we should be able to map back what each individual color is and make sure that it correlates back to one of the A or B standards. In this example, we can look at the back of this cable, and we can put that B standard right next to it and see that each one of those colors does match up. So this particular connector is wired with the T568B standard.
This would be good to try yourself. Grab an Ethernet cable you have sitting around. Have a look at the wires that are on the connector, and see if yours are wired for T568A or T568B.