I understand the number in the naming convention. The number represents how many Megabits per second can the standard support. However, I do not understand the rest of the naming convention. What do "BASE," "T," "X," etc. mean?

Can someone explain what do names mean and how did these standards come into effect?

  • 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 provide and accept your own answer. – Ron Maupin Mar 2 at 23:11

The first number represents the speed.

If the next part is "BASE", then it is baseband. If it is "BROAD", then it is broadband. This is the original meaning of baseband/broadband, not the government idea (any speed at or above an arbitrary speed) of broadband.

The last part is tricky. "2" means about (185) 200 meters. "5" means 500 meters. "36" means 3600 meters. "T" means twisted-pair cable (limited to 100 meters). "TX" is a variation of twisted-pair". Things like "SX" or "LX" are for fiber. "SX" is for short range, "LX" is for long range. There are other variations of fiber, too.

Ethernet (and other LAN standards) is developed by the IEEE. The ethernet IEEE working group is 802.3. There are other working groups, e.g. 802.11 for Wi-Fi, some of which have been disbanded, e.g. 802.5 for token ring, and the standards are frozen.

  • What do "baseband" and "broadband" mean in this context? – Russell Borogove Aug 29 '17 at 21:06
  • Baseband uses the full bandwidth to send data, while broadband only uses part of the bandwidth, allowing simultaneous signals on the same physical link (think cable TV, where you have multiple channels being sent at the same time on the same cable). – Ron Maupin Aug 29 '17 at 21:08
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    I've seen PASS as the second part as well - meaning a specific band that is not a baseband. (10PASS-TS appears to be a thing) – immibis Aug 29 '17 at 23:58

In addition to Ron's answer:

The 'X' in -TX or -SX stands for 4b/5b (100 Mbit/s) or (improved) 8b/10b line code. The 'R' in 10GBASE-SR or -LR stands for (more efficient) 64b/66b line code. A line code is required to enable clock recovery and bit-level synchronization. Without line code, the receiver would lose track of the bit boundaries when many equal bits are transmitted.

-S is for Short wavelength optical (~850 nm), -L for Long wavelength (~1300 nm), -E for Extra long wavelength (~1500 nm) and so on. Short waves are usually used with multi-mode fiber for short distance (less than 1 km), longer waves with single-mode fiber for long distance (1 km to 100 km). These three wavelengths are selected from the low-absorption bands of silica glass.

I've compiled a comprehensive and fairly complete list for Wikipedia a while back, all taken from IEEE 802.3.

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