Is ethernet describing the protocol and therefore cat5 cables became labelled ethernet cables because they are used for this protocol?

  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could post and accept your own answer.
    – Ron Maupin
    Jan 4, 2021 at 1:13

4 Answers 4


The IEEE 802.3 standards define certain L1 characteristics/operation, but do not define the connectors to use to connect the devices.

For instance, while 802.3 does define that 100BASE-TX will use twisted pair cabling that must meet certain characteristices (attenuation, cross talk, etc), it does not define if this must be UTP or some variation of STP. It also doesn't define a certain "Category" of cabling, although typically the cabling "Categories" are designed to meet specific requirements of the 802.3 standards.

With reference to the standard not defining the connector, this is probably best illustrated using fiber as an example. The 802.3 standards define the characteristics/operation of 1000BASE-SX, but you can find 1000BASE-SX connections that use LC, SC, MTRJ, ST or a number of other types of connectors. As long as the connector allows the connection to meet the requirements of the standard, it is perfectly okay to use it.

As to why the cables are called Ethernet cables, I have already addressed that in this answer to a previous question, so it is probably better to view that answer as well rather than for me to copy it here.

  • 1
    It may be worth mentioning the ANSI/TIA/EIA standards which do define the cable categories and characteristics which limit which versions of ethernet which can run on each category, and the 8P8C connectors used on UTP.
    – Ron Maupin
    Jan 29, 2016 at 5:13
  • In a sense I did when I mentioned that the categories were designed to meet the 802.3 standards. There are a number of global standards bodies and it can introduce issues like which standards bodies are involved, how they work (or don't work) together, and how they may have differences in the definition of a particular category. Or things like ISO/IEC having category standards that ANSI/TIA//EIA doesn't recognize as categories at all. I left it abstracted to avoid the whole mess as it really isn't important to the OP's core question of if 802.3 Ethernet defines the connectors as well.
    – YLearn
    Jan 29, 2016 at 8:45

Ethernet runs on various different media, of which UTP cabling is only one medium. There are other LAN and other technologies, such as POTS, which can use UTP cabling.

UTP cabling has various registered categories. Category-5 cabling is no longer registered, and it hasn't been this century. The current registered categories are Category-3, Category-5E, Category-6, and Category-6A. Different variants of ethernet on UTP require a minimum category. For instance, 10 Mb ethernet can run on Category-3 or above, but 100 Mb ethernet requires at least Category-5E.


'Ethernet Cables' really describe RJ45. RJ45 has standards associated to it to carry a Layer 2 (see OSI model) signal called Ethernet.

Other Layer 2 signals include

  • Token Ring

  • MPLS

  • MOE (metro optical ethernet)

RJ45 has two twisted pair that must have a certain amount of twists in them per foot to prevent signal crossover from power cords, radio signals, etc. Additionally, 'the signal' can only traverse a certain amount of distance before the signal attenuates, which is in the standard.

  • 4
    RJ45 is just a connector type for UTP cabling. Ethernet has various layer-1 media besides UTP: coax, fiber, etc.
    – Ron Maupin
    Jan 28, 2016 at 19:59
  • I guess I explained this very poorly. My point is that RJ45 cables, as they are sometimes referred as, have to maintain certain standards to transmit the signal according to the RFP. I'll try and remediate later. Crushed. If you want to answer properly I can delete this post.
    – Citizen
    Jan 28, 2016 at 20:01
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    If we really want to get technical, what is commonly referred to as an RJ45 is not actually a registered jack (i.e. what RJ stands for), rather it is an 8P8C connector. It is similar to the actual RJ45S which likely caused the initial confusion and adoption into normal usage, however the RJ45S is keyed and wired a bit differently. The 8P8C connector we use with Ethernet is not keyed and uses TIA/EIA-568-A or B for it's wiring scheme.
    – YLearn
    Jan 28, 2016 at 22:42

Ethernet is a family of specifications that governs a few different things

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