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An in-depth look into various types of network cabling, focusing on twisted pair and coaxial cables. It explains the concepts of UTP (Unshielded Twisted Pair) and STP (Shielded Twisted Pair), their advantages, and their differences from coaxial cables. The document also covers the internal structure of UTP cables and pinouts for straight and crossover cables.
Typology: Lecture notes
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1. Objective This lab exercise is designed to give students hands on experience of building CAT-5 UTP Ethernet patch cables. 2. Resources Required - CAT 5 Cable - bulk Category 5, 5e or 6 cable - RJ45 Ends - Crimper for RJ - Wire Cutters - to cut and strip the cable if necessary - Wire Stripper - Cable Tester 3. Introduction Network media is the actual path over which an electrical signal travels as it moves from one component to another. There are different types of network cables such as twisted-pair cable (electric) , coaxial cable (electric), and fiber optic cable (light). This section, however, describes only twisted pair and coaxial cables.
3.1 Twisted Pair Cable Twisted-pair cable is a type of cabling that is used for telephone communications and most modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs. When electrical current flows through a wire, it creates a small, circular magnetic field around the wire. When two wires in an electrical circuit are placed close together, their magnetic fields are the exact opposite of each other. Thus, the two magnetic fields cancel each other out. They also cancel out any outside magnetic fields. Twisting the wires can enhance this cancellation effect. Using cancellation together with twisting the wires, cable designers can effectively provide self-shielding for wire pairs within the network media. Two basic types of twisted-pair cable exist: unshielded twisted pair (UTP) and shielded twisted pair (STP). The following sections discuss UTP and STP cable in more detail.
3.2 UTP Cable UTP cable is a medium that is composed of pairs of wires (see Figure 1-1). UTP cable is used in a variety of networks. Each of the eight individual copper wires in UTP cable is covered by an insulating material. In addition, the wires in each pair are twisted around each other.
Figure 1-1 Unshielded Twisted-Pair Cable
difficulty with termination, STP is rarely used in Ethernet networks. STP is primarily used in Europe. The following summarizes the features of STP cable: Speed and throughput—10 to 100 Mbps Average cost per node—Moderately expensive Media and connector size—Medium to large Maximum cable length—100 m (short)
When comparing UTP and STP, keep the following points in mind: The speed of both types of cable is usually satisfactory for local-area distances. These are the least-expensive media for data communication. UTP is less expensive than STP. Because most buildings are already wired with UTP, many transmission standards are adapted to use it, to avoid costly rewiring with an alternative cable type.
3.4 Coaxial Cable Coaxial cable consists of a hollow outer cylindrical conductor that surrounds a single inner wire made of two conducting elements. One of these elements, located in the center of the cable, is a copper conductor. Surrounding the copper conductor is a layer of flexible insulation. Over this insulating material is a woven copper braid or metallic foil that acts both as the second wire in the circuit and as a shield for the inner conductor. This second layer, or shield, can help reduce the amount of outside interference. Covering this shield is the cable jacket.
Figure 1-4 Coaxial Cable
Coaxial cable supports 10 to 100 Mbps and is relatively inexpensive, although it is more costly than UTP on a per-unit length. However, coaxial cable can be cheaper for a physical bus topology because less cable will be needed. Coaxial cable can be cabled over longer distances than twisted-pair cable. For example, Ethernet can run approximately 100 meters (328 feet) using twisted-pair cabling. Using coaxial cable increases this distance to 500m (1640.4 feet). For LANs, coaxial cable offers several advantages. It can be run with fewer boosts from repeaters for longer distances between network nodes than either STP or UTP cable. Repeaters regenerate the signals in a network so that they can cover greater distances. Coaxial cable is less expensive than fiber-optic cable, and the technology is well known; it has been used for many years for all types of data communication.
Figure 1-5 Thinnet and BNC Connector
The following summarizes the features of coaxial cables: Speed and throughput—10 to 100 Mbps Average cost per node—Inexpensive Media and connector size—Medium Maximum cable length—500 m (medium)
4. Internal Structure of the UTP Cable Here is what the internals of the cable look like:
Figure 1-6 Internal Cable Structure and Color Coding
Inside the cable, there are 8 color coded wires. These wires are twisted into 4 pairs of wires; each pair has a common color theme. One wire in the pair being a solid or primarily solid colored wire and the other being a primarily white wire with a colored stripe (Sometimes cable doesn't have any color on the striped cable, the only way to tell is to check which other wire it is twisted around). Examples of the naming schemes used are: Orange (alternatively Orange/White) for the solid colored wire and White/Orange for the striped cable. The twists are extremely important. They are there to counteract noise and interference. It is important to wire according to a standard to get proper performance from the cable. The TIA/EIA-568-A specifies two wiring standards for a 8-position modular connector such as RJ45. The two wiring standards, T568A and T568B vary only in the arrangement of the colored pairs.
5. RJ45 Ends The RJ45 end is an 8-position modular connector that looks like a large phone plug. There are a couple variations available. The primary variation you need to pay attention to is whether the connector is intended for braided or solid wire. For braided/stranded wires, the connector has contacts that actually pierce the wire. For solid wires, the connector has fingers which pierce the insulation and make contact with the wire by grasping it from both sides. Here is a diagram and pinout:
Figure 1-7 RJ45 Jack and Plug Pinout
6.1 Straight Cable
used most of the time and can be used to:
6.2 Crossover Cable
crossover cable can be used to:
In you need to check how crossover cable looks like; both sides (side A and side B) of cable have wire arrangement with following different color.
Commonly used types of UTP cabling are as follows:
Name Typical construction Bandwidth Applications Notes
Level 1 0.4 MHz Telephone and modem lines
Not described in EIA/TIA recommendations. Unsuitable for modern systems.
Level 2 4 MHz Older terminal systems, e.g. IBM 3270
Not described in EIA/TIA recommendations. Unsuitable for modern systems.
Cat.3 UTP 16 MHz 10BASE-T and 100BASE-T4 Ethernet
Described in EIA/TIA-568. Unsuitable for speeds above 16 Mbit/s. Now mainly for telephone cables Cat.4 UTP 20 MHz 16 Mbit/s Token Ring Not commonly used
Cat.5 UTP 100 MHz
1000BASE-T Ethernet Common in most current LANs
Cat.5e UTP 100 MHz
1000BASE-T Ethernet
Enhanced Cat5. Same construction as Cat5, but with better testing standards.
Cat.6 UTP 250 MHz 10GBASE-T Ethernet
Most commonly installed cable in Finland according to the 2002 standard. SFS-EN 50173-
Cat.6a U/FTP, F/UTP 500 MHz 10GBASE-T Ethernet Adds outer shielding. ISO/IEC 11801:2002 Amendment 2.
Cat.7 F/FTP, S/FTP 600 MHz
Telephone, CCTV, 1000BASE-TX in the same cable. 10GBASE- T Ethernet.
Fully shielded cable. ISO/IEC 11801 2nd Ed.
Cat.7a F/FTP, S/FTP 1000 MHz
Telephone, CATV, 1000BASE-TX in the same cable. 10GBASE- T Ethernet.
Uses all four pairs. ISO/IEC 11801 2nd Ed. Am. 2.
Cat.8.1 U/FTP, F/UTP 1600- 2000 MHz
Telephone, CATV, 1000BASE-TX in the same cable. 40GBASE- T Ethernet.
In development.
Cat.8.2 F/FTP, S/FTP
2000 MHz
Telephone, CATV, 1000BASE-TX in the same cable. 40GBASE- T Ethernet.
In development.
7. Procedure to make Ethernet Cables 1. Strip off about 2 inches of the cable sheath. 2. Untwist the pairs - don't untwist them beyond what you have exposed, the more untwisted cable you have the worse the problems you can run into. 3. Align the colored wires according to the diagrams above. 4. Trim all the wires to the same length, about 1/2" to 3/4" left exposed from the sheath. 5. Insert the wires into the RJ45 end - make sure each wire is fully inserted to the front of the RJ45 end and in the correct order. The sheath of the cable should extend into the RJ45 end by about 1/2" and will be held in place by the crimp. 6. Crimp the RJ45 end with the crimper tool
Crimper tool
Note: a) This assignment must be submitted before the next lab. b) The assignment submitted must be in proper format as instructed by the teacher to get maximum marks. c) Marks will be deducted on late submissions. d) Cheating or using any unfair means will award ZERO marks.
