Alphabet soup, jargon, and Ethernet LAN specs

In a recent thread, the OP asked about maximum distance for an Ethernet cable. In the ensuing discussion, a fair about of misinformation was posted, along with some confusing (but irrelevant) distinctions.

At the crux of the problem, I think, is a general lack of understanding of the nomenclature of Ethernet LANs, and the reasoning behind some of the specification limits. One of the posters took offense at my attempts to guide the discussion. So, I’m posting this separately. Hopefully, it will help. And, sorry, Mr Wolf, I did not intend to offend or belittle.

Cable Types:
Cat3 – voice grade twisted pair
Cat5 – data grade twisted pair
Cat5e – Cat5 enhanced; offers improved bandwidth and improved signal attenuation characteristics compared with Cat5. Can handle 1000Mbps.
Cat6 / Cat6e – Improved bandwidth & improved signal attenuation, especially at higher frequencies. Not often used in home networks (except by the terminally geeky ).

10, 100, 1000
Simply the speed of the LAN in Mbps (megabits per second). Divide by 8 to convert to MB/sec (megabytes per second). The latter unit of measure is typically used in hard drive interface specifications (ATA100 = 100 MB/sec).

BASE
Simply stands for “baseband”. Nobody except network experts cares what "baseband" means.

T, TX, T4
“T” simply stands for “twisted pair.” If it is not stated otherwise, that means it is using two pairs of wires – on pair for transmit, the other pair for receive (that is, four wires). “TX” is simply “T” for 100MBps with Cat5 cable (instead of Cat3 which was the minimum for 10Base-T). 100Mbps fast Ethernet also has a 100Base-T4 variation that allows the use of Cat3 cable over 4 pairs (8 wires). T4 is defunct. There was also a 100-Base-T2 over Cat3 cable that is also defunct.

Distance specs
For 10Mbps Ethernet, the 100M distance was limited by signal attenuation over the voice grade cable. With Cat5 cable, you can actually go 150M (or maybe farther) with 10Mbps Ethernet. But, that is largely moot since nobody is putting in new 10Mbps networks anymore. For 100Mbps and higher, the distance is limited by signal timing, not signal attenuation (assuming you are using the approved cable). So, no matter the cable grade, it will still take the same amout of time for the signal to go 100 meters.

Hope that helps.