Twisted Pair Ethernet (100baseTX/100BaseT4)

by Johannes Helmig [Published on 13 April 2001 / Last Updated on 13 April 2001]

When it comes to the Cabling rules, the High-Speed 100 MHz 100baseT is very similar to Twisted Pair Ethernet (10baseT/UTP), except: it does not make sense to connect 100baseT-hubs with a 10base2 (10Mhz) Backbone (for even faster networking, you can use Gigabit-Ethernet (1000baseT), which uses a different cable ).

When it comes to the cabling:
100baseT requires UTP
cat 5 cable !

Don't try to save on the cable (100 Mhz is a very high frequency) !


And there are different kinds of cables:
- 100baseTX for 4-wire (same as 10baseT)
- 100baseT4 for 8-wire cable

In case you need a patch/cross-cable to make a direct connection between 2 PCs or hubs, here is the wiring rules ( a cross-cable for 1000baseT has different wiring ! )

100baseTX:


You can use for 100baseTX the same rules as for Twisted Pair Ethernet (10baseT/UTP)


100 baseT4:


However: due to the high frequencies: get a hub (price for 100baseT hubs are coming down fast ) !


most 100Mhz network cards ("FastEthernet") can also operate as 10baseT, when connected to
a 10baseT hub (allowing to install already systems with the FastEthernet network cards but not
having to upgrade the network cabling, which can then be done later by swapping a 10Mhz hub
with a 100 Mhz hub or switch , assuming that the cabling has also be upgraded to be able to
handle the 100 Mhz ).

Some hubs are only for 10 Mhz, some hubs are only for 100 Mhz, and some allow to connect
10 Mhz or 100 Mhz : Dual-Speed Hubs:


( while usually the AutoSelection/Configuration is working well, there may be some situations
where it fails and the network will not operate at all and a manual configuration of Media-Speed
or of the Duplex-Mode is required )

For building larger networks with multiple hubs, the configuration rules are the same as for
Twisted Pair Ethernet (10baseT).

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