Network cables are used to connect two or multiple networking devices in a network. There are three network cable types commonly used for networking:-
1. Coaxial cable
2. Twisted pair,
3. Fiber-optic cabling.
In today’s LANs, the twisted pair cabling is the most popular type of cabling, but the fiber-optic cabling usage is increasing, especially in high-performance networks. Coaxial cabling is generally used for cable Internet access. Let’s explain all three cable types in more detail.
1. Coaxial cabling
A coaxial cable has an inner conductor that runs down the middle of the cable. The conductor is surrounded by a layer of insulation which is then surrounded by another conducting shield, which makes this type of cabling resistant to outside interference. This type of cabling comes in two types – thinnet and thicknet. Both types have a maximum transmission speed of 10 Mbps. Coaxial cabling was previously used in computer networks, but today are largely replaced by twisted-pair cabling
Coaxial cable contains a conductor, insulator, braiding, and sheath. The sheath covers the braiding, the braiding covers the insulation, and the insulation covers the conductor.
Sheath is the outer most layer of the coaxial cable. It protects the cable from physical damage.
A braided shield uses a tightly woven lattice of thin tin or copper wires to encapsulate a shielded cable assembly. It protects signals from external interference and noise. This shield is built from the same metal that is used to build the core.
Insulation protects the core. It also keeps the core separate from the braided shield. Since both the core and the braided shield use the same metal. Insulation is used to avoid short-circuit between core and braided shield
The conductor carries electromagnetic signals. Based on conductor a coaxial cable can be categorized into two types:-
1. single-core coaxial cable, and
2. multi-core coaxial cable.
A single-core coaxial cable uses a single central metal (usually copper) conductor, while a multi-core coaxial cable uses multiple thin strands of metal wires. The following image shows both types of cable.
Coaxial cables in computer networks
The coaxial cables were not primarily developed for the computer network. These cables were developed for general purposes. They were in use even before computer networks came into existence. They are still used even their use in computer networks has been completely discontinued.
At the beginning of computer networking, when there were no dedicated media cables available for computer networks, network administrators began using coaxial cables to build computer networks.
Because of its low cost and long durability, coaxial cables were used in computer networking for nearly two decades (the 80s and 90s). Coaxial cables are no longer used to build any type of computer network.
Specifications of coaxial cables
Coaxial cables have been in use for the last four decades. During these years, based on several factors such as the thickness of the sheath, the metal of the conductor, and the material used in insulation, hundreds of specifications have been created to specify the characteristics of coaxial cables.
From these specifications, only a few were used in computer networks. The following table lists them.
|RG-6||75||18||Solid copper||Used in cable network to provide cable Internet service and cable TV over long distances.|
|RG-8||50||10||Solid copper||Used in the earliest computer networks. This cable was used as the backbone cable in the bus topology. In Ethernet standards, this cable is documented as the 10base5 Thicknet cable.|
|RG-58||50||24||Several thin strands of copper||This cable is thinner, easier to handle and install than the RG-8 cable. This cable was used to connect a system with the backbone cable. In Ethernet standards, this cable is documented as the 10base2 Thinnet cable.|
|RG-59||75||20 – 22||Solid copper||Used in cable networks to provide short-distance service.|
- Coaxial cable uses RG rating to measure the materials used in shielding and conducting cores.
- RG stands for the Radio Guide. Coaxial cable mainly uses radio frequencies in transmission.
- Impedance is the resistance that controls the signals. It is expressed in the ohms.
- AWG stands for American Wire Gauge. It is used to measure the size of the core. The larger the AWG size, the smaller the diameter of the core wire.
2. Twisted-pair cabling
A twisted pair of cables was primarily developed for computer networks. This cable is also known as Ethernet cable. Almost all modern LAN computer networks use this cable.
A twisted-pair cable has four color-coded pairs of insulated copper wires. These wires are twisted around each other to reduce crosstalk and outside interference.
Every two wires are twisted around each other to form pair. Each pair has one solid color and one stripped color wire. Solid colors are blue, brown, green, and orange.
There are two types of twisted-pair cable: –
- UTP (Unshielded Twisted-Pair) cable. All pairs are wrapped in a single plastic sheath.
- STP (Shielded Twisted-Pair) cable. Each pair is wrapped with an additional metal shield, then all pairs are wrapped in a single outer plastic sheath. An additional layer of insulation protects data from outside interferences.
Similarities and differences between STP and UTP cables
- Both STP and UTP can transmit data at 10Mbps, 100Mbps, 1Gbps, and 10Gbps.
- Since the STP cable contains more materials, it is more expensive than the UTP cable.
- Both cables use the same RJ-45 (registered jack) modular connectors.
- The STP provides more noise and EMI resistance than the UTP cable.
- The maximum segment length for both cables is 100 meters or 328 feet.
- Both cables can accommodate a maximum of 1024 nodes in each segment.
To Learn how twisted-pair cables are used in the LAN network. you can check this tutorial.
This tutorial explains about straight-through cable and a cross-over cable
3. Fiber-optic cabling
This type of cabling uses optical fibers to transmit data in the form of light signals. The cables have strands of glass surrounded by cladding material. Fiber Optic can transmit up to 40 kilometers at a speed of 100Gbps.
This cable consists of a core, cladding, buffer, and jacket. The core is made from thin strands of glass or plastic that can carry data over a long distance. The core is wrapped in the cladding; the cladding is wrapped in the buffer, and the buffer is wrapped in the jacket.
- This type of cabling can support greater cable lengths than any other cabling type (up to a couple of miles).
- The cables are also immune to electromagnetic interference.
- Core carries the data signals in the form of light.
- Cladding reflects light back to the core.
- Buffer protects the light from leaking.
- The jacket protects the cable from physical damage.
There are two types of fiber-optic cables:
- Single-mode fiber (SMF) – uses only a single ray of light to carry data. Used for larger distances.
- Multi-mode fiber (MMF) – uses multiple rays of light to carry data. Less expensive than SMF.
SMF (Single-mode fiber) optical cable
This cable carries only a single beam of light. This is more reliable and supports much higher bandwidth and longer distances than the MMF cable. This cable uses a laser as the light source and transmits 1300 or 1550 nano-meter wavelengths of light.
MMF (multi-mode fiber) optical cable
This cable carries multiple beams of light. Because of multiple beams, this cable carries much more data than the SMF cable. This cable is used for shorter distances. This cable uses an LED as the light source and transmits 850 or 1300 nano-meter wavelengths of light.
Four types of connectors are commonly used:
- ST (Straight-tip connector)
- SC (Subscriber connector)
- FC (Fiber Channel)
- LC (Lucent Connector)