The 100Base-TX (sometimes referred to 100Base-T)
cable is
the most popular cable around since it has actually replaced the older
10Base-T
and 10Base-2 (Coaxial). The 100Base-TX cable provides fast speeds up to
100Mbits
and is more reliable since it uses CAT5 cable (see
the CAT 1/2/3/4/5 page).There is also 100Base-T4 and 100Base-FX
available,
which we discuss later.
So what does 100Base-TX/T4/FX mean?
We are going to break the "100Base-T" into
three
parts so we can make it easier to understand:
100
The number 100 represents the frequency in MHz
(Mega HertZ)
for which this cable is made. In this case it is 100 MHz. The greater
the MHz,
the greater speeds the cable can handle. If you try to use this type of
cable
for greater frequencies (and, therefore, speeds) it will either not
work or
become extremely unreliable. The 100 MHz speed translates to 100Mbit
per
second, which in theory means 12 Mbps. In practice though, you wouldn't
get
more than 4 Mbps.
Base
The word "Base" refers to Baseband. Baseband is
the
type of communication used by Ethernet and it means that when a
computer is
transmitting, it uses all the available bandwith, whereas Broadband
(cable
modems) shares the bandwidth available. This is the reason cable modem
users
notice a slowdown in speed when they are connected on a busy node, or
when
their neighbor is downloading all the time at maximum speed! Of course
with
Ethernet you will notice a slowdown in speed but it will be smaller in
comparison to broadband.
TX/T4/FX
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. The 100Base-T is used
sometimes
to refer to the 100Base-TX cable specification. For more information,
see the
"UTP
-Unshielded Twisted Pair" page where you can find
information
on pinouts for the cables. All 100MB rated cables, except the
100Base-FX, use
CAT5 cable.
100Base-TX
The TX (sometimes referred as "T" only)
means it's a CAT5 UTP straight through cable using two of the four
available
pairs and supports speeds up to 100 Mb. Maximum length is 100 meters
and
minimum length between nodes is 2.5 meters.
100Base-T4
The T4 means it's a CAT5 UTP straight
through cable
using all four available pairs and supports speeds up to 100 Mb.
Maximum length
is 100 meters and minimum length between nodes is 2.5 meters.
100Base-FX
The FX means it's a two strand fiber cable
and
supports speeds up to 100 Mbs. Maximum length is usually up to two kms.
To summarize, keep the following in mind:
- 100Base-TX/T4 works for 100 Mb
networks only and uses unshielded twisted pair cable with RJ-45
connectors at each end
- All CAT5 UTP cables have four pairs of
cables (eight wires).
- 100Base-TX (sometimes called
100Base-T) uses two of the four available pairs within the UTP cable,
whereas the 100Base-T4 uses all four pairs.
- 100Base-FX also works for speeds up to
100 Mb but uses fiber optic cable instead of UTP.
Cabling tips for network professionals series
Lesson 1: Network history and fundamentals
Lesson 2: Straight-through UTP cables
Lesson 3: CAT5 UTP crossover cable
Lesson 4: 10Base-T/2/5/F/35 - Ethernet
Lesson 5: 100Base-(T) TX/T4/FX - Ethernet
Lesson 6: Fiber cable
Lesson 7: Direct cable connection
Lesson 8: Serial direct cable connection
Lesson 9: Parallel direct cable connection
Lesson 10: USB direct cable connection
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