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Making Sense of IEEE Ethernet Standards

Making Sense of IEEE Ethernet Standards

Have you ever noticed that when you look at networking equipment, there are a lot of keywords and numbers and phrases? For instance, have you ever seen something like IEEE 802.3?

Have you ever wondered what all of this means?

Well, these designations refer to the IEEE Ethernet standards, and it turns out that learning a little bit about how these standards are named can give you a ton of useful information. If you want to take a minute to acquire this knowledge, you’ll find a nice crash course below.

What Is IEEE 802.3?

The first thing to learn is that the IEEE 802.3 standard is an international standard that makes sure everyone is on the same page when it comes to modern LAN networking. In other words, if you’re plugging a device into another device in order to make a network, you’re probably using equipment that adheres to these standards.

The standards are set and updated by the Institute of Electrical and Electronics Engineers (IEEE), and the 802.3 standard specifically refers to LAN networking.

Later, we’ll get into the specifics of the most common 802.3 standards, but there are a lot of variations. When you understand how to read the convention and standards, then you can figure out a lot about a network simply by looking at the name of the standard.

How Do You Read It?

So, let’s learn how to do that. The common convention is to start with a number. Then, you might see the word “Base.” After that is a hyphen and a letter (or letters). Each of these three components is telling you something specific.

Starting with the number, this explains the maximum data speeds supported by the standard. Generally, this is denoted in Mbps, but for very fast standards, you might see something like “10G.” The “G” there is telling you that the number is in Gbps instead of Mbps.

As for “Base,” this is also telling you something. It’s short for baseband, and it means that the signal is not being modulated at all for the standard. If you don’t see “Base,” then you are looking at a modulated signal.

Lastly, there is the letter convention. This is telling you what types of cables are used with each standard. There are a lot, but the ones you need to know are easy to list:

  • T: twisted pair
  • F: fiber optics
  • TX: Fast Ethernet
  • FX: Fast Ethernet over fiber optics
  • CX: copper twisted pair
  • SX: multimode fiber
  • LX: single-mode fiber

Simply knowing these rules of the naming convention already tells you everything you need to know about a standard, but we can get into more details for some of the most common standards.

The Common Standards

Again, the list below does not cover every standard. There are a lot. But, these are the standards you are most likely to see in a modern network.


The first and oldest among the standards in this list, 10Base-T is formally known as IEEE 802.3. You’ll notice that nothing comes after the “3” because this is the original 802.3 standard. Using the naming convention, this is a connection that runs over twisted pair cables and can reach speeds of 10 Mbps. These cables max out at 100 meters in length.


IEEE 802.3u is next on the list. This is a 100 Mbps connection that runs on Fast Ethernet. In fact, this is known commonly just as “Fast Ethernet.” This standard supports Cat5, 5e, and 6 Ethernet cables. Fast Ethernet does also run on twisted pairs, and it supports cable runs up to 100 meters.


The formal designation here is IEEE 802.3u. You might notice that the IEEE designation is identical to the connection above. That’s because this is also fast Ethernet. The important difference is that this form uses multimode fiber that supports cable runs up to 412 meters in length. Otherwise, the general performance is still very much in the range of Fast Ethernet.


Known as IEEE 802.3z, this is a copper twisted cable pair. While this standard supports higher speeds than the previous standards on the list, the cable runs are much shorter. 1000Base-CX can only maintain 1000 Mbps speeds at runs of 25 meters or less.


IEEE 802.3ab is the first form of what is commonly called “Gigabit Ethernet.” Since 1000 Mbps is the same as 1 Gbps, that’s the source of the name. This is a twisted-pair standard that supports these speeds at lengths of 100 meters per cable run. Most Ethernet hardware that you purchase today will support this standard.


The next Gigabit standard on the list is IEEE 802.3z. This form runs on multimode fiber optics. The performance is similar to that of 1000Base-T, but the implementation of multimode fiber allows cable runs much longer than 100 meters without dropping speeds.


This standard also uses the IEEE 802.3z designation. That’s because it provides the same performance. The key difference is found in the standard name. LX refers to single-mode fiber instead of multimode fiber. Ultimately, single-mode fiber supports even longer distances than multimode fiber (getting into km ranges).


The last of our common connection types is This is a twisted-pair standard that supports 10 Gbps connections. These are the fastest of the common connections, and this standard utilizes Ethernet cables, supporting Cat5e, 6, and 7 cable types.

That’s it. That covers the most common IEEE standards for modern LAN networking, and now that you know the convention, you can read other standards at a glance too.


Understanding IEEE 802.3 Ethernet standards can provide valuable insights into your network equipment and help you make informed decisions when setting up or upgrading your LAN networking infrastructure. By deciphering the naming conventions, you can quickly identify the data speeds, cable types, and modulation techniques used in various standards, making it easier to create a network that suits your needs.

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