Base-T and Base-TX

Hey guys i just wondered if you can clear something up for me. It's just something minor but would probably help if i knew it...

In 100 base t and 100 base tx, i know that tx = full duplex (ie all 4 pairs) and 100 base t = 2 pairs used, but what is the specific meaning of T and X?

Thanks!

Ps. looked on google and firewall, can't find anything specific.

NeoTech you ask a very detailed question that many network guys simply look past.

The "T" refers to "Twisted Pair" physical medium that carries the signal. This shows the structure of the cable and tells us it contains pairs which are twisted. For example, UTP has twisted pairs and this is the cable used in such cases. For more information, see the "UTP -Unshielded Twisted Pair" page where you can find information on pinouts for the cables.

Source: www.firewall.cx/cabling_10baseT.php


ZiPPy

That's interesting. I'd always believed that 10BaseT is 10Mbps over twisted pair cabling and, when the cable standard improves to allow a transmission speed of 100Mbps, this is reflected by the "T" changing to "TX", almost as if the additional "X" means "extended" or "extra". I suppose it's similar to 10BaseF and 100BaseFX.

I'll be interested to see how other folks interpret this.

Some common standards that use twisted pairs are: 10BASE-T, 100BASE-TX, 100BASE-T4, 100BASE-T2 and 1000BASE-T

Wikipedia says that if there are multiple standards for the same transmission speed, they are distinguished by a letter or digit following the T, such as TX, T4, T2 en.wikipedia.org/wiki/10BASE-T

However, this doesn't seam to be a rule for other standards. For example, there is 100BASE-FX, 100BASE-BX, 100BASE-SX. But there is no such things as 100BASE-F, 100BASE-S, 100BASE-B . At least in the official Cisco academy stuff.

Any other ideas ?

@S0lo - you raise a good point. I've always been confused by the extensive tables that I met in CCNA1 detailing the 10Base(whatever), 100base(whatever) and 1000base(whatever) and their maximum cable lengths along with the actual medium used. If only there was some consistency in nomenclature - that would make everyone's life easier! Of course everyone learns these to pass the exams then I suspect that they're forgotten, unless a particular cable or subset of the whole lot is/are used on a day-to-day basis.

The X as i understand it means the signal can travel both ways (simultanious send and receive) as oppossed to uni directional signalling that you get in say single-cable token ring networks...

This is probably why there is no 10base-TX, as 10mbps ethernet didnt support full duplex. All the ones you guys mentioned that are only in X variants probably dont have a uni-directional transmission variant. :shock: