Ethernet cable summary
- a summary of the different types of cable used for the different types of
Ethernet including 10Base-T and 100Base-T, etc. A description of Cat 5 and other
category cables is provided as well as Cat-5 crossover cables. This type of
cable uses RJ45 connectors and accordingly is often referred to as RJ45 network
cable, or RJ45 patch cable.
The Ethernet standard is well established. It is used in a
variety of different environments and accordingly there is a variety of
different types of cable over which it operates. It is possible not only for
Ethernet to operate at different speeds, but there are different varieties of
cable that can be used within the same speed category. In order to ensure that
Ethernet operates correctly, the types of cable, their electrical conditions and
the maximum lengths over which they may operate are specified.
For many applications, ready made Ethernet cables may be
purchased, and a knowledge of the construction of any Ethernet cables is not
required. However for other applications it is necessary to know the
construction of the Ethernet cable. As a result of this advertisements for
different types of cable, Cat-5, Cat-5e, Cat-6 may be widely seen. These cables
may be used for different applications.
A summary of Ethernet cables and their maximum operating
lengths is given below:
| Specification |
Cable type |
Maximum length |
| 10BaseT |
Unshielded Twisted Pair |
100 metres |
| 10Base2 |
Thin coaxial cable |
180 metres |
| 10Base5 |
Thick coaxial cable |
500 metres |
| 10BaseF |
Fibre optic cable |
2000 metres |
| 100BaseT |
Unshielded twisted pair |
100 metres |
| 100BaseTX |
Unshielded twisted pair |
220 metres |
Ethernet cable type summary
Lengths provided are those accepted as the maximum.
These lengths are not necessarily included in the IEEE standard.
Categories for Ethernet cables
A variety of different cables are available for Ethernet and
other telecommunications and networking applications. These cables that are
described by their different categories, e.g. Cat 5 cables, Cat-6 cables, etc,
which are often recognised by the TIA (telecommunications Industries
Association) and they are summarised below:
- Cat-1: This is not recognised by the TIA/EIA. It is the form
of wiring that is used for standard telephone (POTS) wiring, or for ISDN.
- Cat-2: : This is not recognised by theTIA/EIA. It was the form
of wiring that was used for 4Mbit/s token ring networks.
- Cat-3: : This cable is defined in TIA/EIA-568-B. It is used
for data networks employing frequencies up to 16 MHz. It was popular for use
with 10 Mbps Ethernet networks (100Base-T), but has now been superseded by
Cat-5 cable.
- Cat-4: : This cable is not recognised by the TIA/EIA. However
it can be sued for networks carrying frequencies up to 20 MHz. It was often
used on 16Mbps token ring networks.
- Cat-5: : This is not recognised by the TIA/EIA. It is the
cable that is widely used for 100Base-T and 1000Base-T networks as it
provides performance to allow data at 100 Mbps and slightly more (125 MHz
for 1000Base-T) Ethernet.
- Cat-5e: : This form of cable is recognised by the TIA/EIA and
is defined in TIA/EIA-568-B.. It has a slightly higher frequency
specification that Cat-5 cable as the performance extends up to 125 Mbps. It
can be used for 100Base-T and 1000Base-t (Gigabit Ethernet).
- Cat-6: : This cable is defined in TIA/EIA-568-B. It provides
more than double the performance of Cat-5 and Cat-5e cables allowing data at
up to 250Mbps to be passed.
- Cat-7: : This is an informal number for ISO/IEC 11801 Class F
cabling. It comprises four individually shielded pairs inside an overall
shield. It is aimed at applications where transmission of frequencies up to
600 Mbps is required.
Further descriptions of cat-5 and Cat-5e cables are given
below as these are widely sued for Ethernet networking applications today.
Cat 5 cable
Cat 5 cables or to give them their full name category 5 cable
is the current preferred cable type for LAN network and telephone wiring where
twisted pair cabling is required. Cat 5 cables consist of an unshielded cable
comprising four twisted pairs, typically of 24 gauge wire. The terminating
connector is an RJ-45 jack. In view of this these Cat5 network cables are often
referred to as RJ45 network cables or RJ45 patch cables. Certified Cat-5 cables
will have the wording "Cat-5" written on the side. As they conform to EIA/TIA
568A-5, this is written on the outer sheath. It is always best to use the
appropriate network cables when setting up a network as faulty or not to
standard cables can cause problems that may be difficult to identify and trace.
Cat5 network cable is now the standard form of twisted pair
cable and supersedes Cat 3. The Cat 5 cables can be used for data speeds up to
125 Mbps, thereby enabling them to support 100Base-T which has a maximum data
speed of 100 Mbps whereas the Cat-3 cable was designed to be compatible with
10Base-T. The Cat5 cable is able to support working up to lengths of 100 metres
at the full data rate.
Where it is necessary to operate at higher speeds, as in the
case of Gigabit Ethernet, an enhanced version of Cat 5 cable known as Cat 5e is
often recommended, although Cat 5 is specified to operate with Gigabit Ethernet,
1000Base-T. Alternatively Cat 5e can be used with 100Base-T to enable greater
lengths (up to 350 metres) to be achieved.
The wires and connections within the Cat 5 or Cat 5e cable
vary according to the applications. A summary of the signals carried and the
relevant wires and connections is given in the table below:
Pin
No |
Colour |
Tele phone |
10 Base -T |
100 Base -T |
1000 Base -T |
PoE
Mode A |
PoE
Mode B |
| 1 |
White / green |
|
+TX |
+TD |
+BI _DA |
48 V out |
|
| 2 |
Green |
|
-TX |
-TX |
-BI _DA |
48 V out |
|
| 3 |
White / orange |
|
+RX |
+RX |
+BI_DB |
48 V return |
|
| 4 |
Blue |
Ring |
|
|
+BI _DC |
|
48 V out |
| 5 |
Blue / white |
Tip |
|
|
-BI _DC |
|
48 V out |
| 6 |
Orange |
|
-RX |
-RX |
-BI_DB |
48 V return |
|
| 7 |
White / brown |
|
|
|
+BI_DD |
|
48 V return |
| 8 |
Brown |
|
|
|
-BI_DD |
|
48 V return |
RJ-45 / Cat 5 / Cat 5e Wiring
In the table, TX is transmitted data, and RX is received
data. BI_Dn is bi-directional data, A, B, C, and D.
Cat 5 crossover cables
There are a number of different configurations of cable that
may be employed according to the equipment and the requirement. The most common
type are the straight through cables which are wired in a 1 to 1 configuration.
However Cat-5 crossover cables are also required on occasions.
Typically a Cat-5 cable used to connect a computer (PC) to a
switch will be a straight through cable. However if two computers or two
switches are connected together then a Cat5 crossover cable is used.
Many Ethernet interfaces in use today are able to detect the
type of cable, whether it is a straight through or crossover cable, and they are
able to adapt to the required format. This means that the requirement for Cat-5
crossover cables is less than it might otherwise be.
When using Cat-5 Ethernet crossover cables, they are not
marked with the fact that they are crossover cables. Accordingly it is often
wise to mark them to avoid confusion later.
Cat 5e cables
In order to improve the performance of the cabling used for
Ethernet and other applications, the Cat 5 cable was upgraded to cat 5e. This
cable provides for improved levels of screening and reduced cross-talk. This is
achieved by having individually screened twisted pairs.
Summary
Cat 5 network cable is now the standard for networking. Using
a cost effective RJ45 connector, these cables may often be referred to as RJ45
network cable or RJ45 patch cable as they are able to link or patch different
Ethernet items together very easily. Now with the introduction of Cat 5e
Ethernet cables, these are becoming more widespread in their use.
Although this is not a complete summary of all the types of
Ethernet cable that may be found, it gives a guide to some of the most common.
10Base-T and 100Base-T are possibly the most widely used forms of Ethernet,
although higher speeds are now becoming common place. In addition to this the
variety of cables including Cat-5 cable and all its versions including crossover
Cat 5 cables may be required and obtained from a variety of suppliers.
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