Twisted Pair Ethernet (10baseT/UTP)

by Johannes Helmig [Published on 24 March 2001 / Last Updated on 24 March 2001]

Note: most of the rules for 10BaseT are also valid for Twisted Pair Ethernet (100baseTX/100BaseT4)

Twisted Pair Ethernet (10baseT), sometime also called "UTP" from "Unshielded Twisted Pair", is based on using a cable similar to phone-wiring. The cable is connected via an RJ-45 connectors to the network card installed in the PC.

If you have a Combo / Multi-Connector network Board, check whether you need to configure the RJ45 plug (it is not always done automatically ! ).

These Twisted Pair cables connect now each PC to the "hub":

which is amplifying and distributing the signal to other connected systems.

Hubs are available in different configuration, with 4, 8, 12, 15 or 24 RJ-45 connections (and most models offer also a BNC-connector for connection of a 10base2 Thin Ethernet cable).
You can plug in the RJ45-connector into a hub while the network is running on the other connected systems, allowing to move / add systems without having to shutdown the network (see : Twisted Pair versus Coax: Reliability / Advantages )

When the network grows, you may need a second hub:

Warning: there are different cable to connect the hubs !
If the hub has only regular connectors, the cable MUST be a cross-cable !

However, some hubs offer special connectors for use of 'Standard' cables
to connect between hubs (that depends on the hub, check the hub's manual)
or a switch, able to select : 'workstation' or ' hub' connection.

Have a look at the back of your hub:

Usually the ports are numbered, and the highest port has a switch labeled"
"Uplink" or something like "MDI/X" in the picture above, allowing you
to configure the port for connection to another hub using a regular cable.
Note: if you use a regular cable to connect 2 hubs, ONLY one hub must
configure the port for this purpose, on the other hub you MUST connect
the cable to a regular port :


For even larger networks, more hubs are required:

Again, watch out for the type of cable required to connect the hubs.

Often , you find a combination of Twisted-Pair and Thin Ethernet (10base2) cabling:

A Thin-Ethernet cable is used to connect the hubs, such a cable is then often called "the backbone", because it carries all the traffic to/from the server.
Warning: the Thin Ethernet (10base2) backbone MUST follow the 10base2 specifications (length, terminators,...).
Warning: a network cannot grow unlimited in the number of hubs and repeaters
(see: Large Networks: 5-4-3 Rule) and on very large network configurations, it may be required to install Switches to optimize the network utilisation.


When connecting just 2 PC's together, there is a possibility to do it without a hub:

BUT: it is now a different type of cable: it is a "crossed" 10baseT cable !
Using a 'regular' cable (which is supposed to be used for connection to a hub) is a common
cause of error, such a 'regular' or 'straight' 10baseT cable does NOT work in such a configuration
without a hub.

I strongly suggest to purchase a cable, but if you think you can make it properly, here is the layout
of such a crossed 10baseT-cable
(i.e 10 MHz, this cable is NOT for 100baseT/100Mhz, for that look at Twisted Pair Ethernet (100baseTX/100BaseT4))

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