Network Cabling

This is a key part of most networks. Even those that rely heavily on wireless will require at least a minimum of cabling.

There are two main types of cabling in use today:

1. Unshielded Twisted Pair (UTP) cable.
   
   UTP cable has had a number of different incarnations. The first that had a wide impact was Category 4, which supported 10Mbps networks (known as 10Base-T). This was soon replaced by Category 5, which supported 100Mbps (100Base-TX), Category 5e and Category 6 which support 1Gbps (1000Base-T/TX). Category 6a also supports 10Gbps Ethernet to a limited extent. Virtually all Category 5, 5e, 6 and 6a cable is eight core (four twisted pairs).
   
   10Base-T and 100Base-TX will work with two twisted pairs so it is a well documented (but unapproved!) practice to run two Ethernet links down a single 8-core UTP cable. This should be avoided as performance and range are degraded.
   
   1Gbps and 10Gbps Ethernet requires all 4 pairs so a cable can carry only a single connection. More recent Category 7 and 7a cables are categorized up to higher speeds than Cat 6 and 6a, but have a shielded construction that will require shielded connectors (as do some Cat6 cables)...
   
   Generally, cables laid into ducts in buildings will be solid-core UTP terminated in wall-mounted 8P8C (or 'RJ45') sockets or 19" rack-mounted 8P8C jack strips. These are fitted using a 'punch-down' tool similar to those used for telephone connections.
   
   Patch leads that connect between devices and the 8P8C sockets will generally use multi-strand UTP cable (for increased flexibility) terminated with crimped-on 8P8C plugs. Generally, unless you intend to manufacture lots of special or non-standard patch leads, commercial patch leads should be used as the attrition rate for unskilled manufacture of patch leads by hand crimping is very high!
2. Fiber Optic cable.
   
   The use of fiber optic cable in home and small business LANs is extremely limited. It is far more fragile and difficult to handle than UTP and the cut fragments of fiber present a significant health and safety hazard. Normally, all work on fiber should be carried out by specialist contractors.
   
   The two major types of fiber are:
   
   • Multi-mode, where the diameter of the glass core is much larger than the wavelength of the light. This means that there are multiple different paths the light can take within the fiber and hence there is a significant variability to how long the light pulses take to traverse the fiber. This results in loss of definition of the pulses and severely limits the range that can be achieved to a few hundred meters. Recently, however, multi-frequency interface cards have been introduced to allow several different signals to be passed through a single fiber to achieve greater bandwidth.
   • Single-mode fiber has a core of similar diameter to a wavelength of light. The light is constrained to a single path and much greater ranges can be achieved (up to 70km), at the expense of much greater cost.
   All fibre is extremely sensitive to handling, and tight curves and excessive flexing must be avoided. If the fiber bends too tightly, or the core fractures, the range and performance of the fiber can be grossly reduced.
   

Most small networks will use Unshielded Twisted Pair (UTP) cables exclusively. The cost and fragility of Fiber Optic cables tend to limit their use to server rooms, extended LAN or WAN connections or backbone connections between buildings or floors of buildings.

Historically,there were two other types of Ethernet network cable. Both used coaxial cable. The original (10Base5) became known a 'Thick wire' and the later 10base2 became known as 'Thin wire'. Old equipment to this standard can still be found in second-hand sales, but should be avoided!