UTP Cabling Standards and Connectors (30.4.2)
UTP cabling conforms to the standards established jointly by the TIA/EIA. Specifically, TIA/EIA-568 stipulates the commercial cabling standards for LAN installations and is the standard most commonly used in LAN cabling environments. Some of the elements defined are as follows:
- Cable types
- Cable lengths
- Connectors
- Cable termination
- Methods of testing cable
The electrical characteristics of copper cabling are defined by the Institute of Electrical and Electronics Engineers (IEEE). IEEE rates UTP cabling according to its performance. Cables are placed into categories based on their ability to carry higher bandwidth rates. For example, Category 5 cable is used commonly in 100BASE-TX Fast Ethernet installations. Other categories include Enhanced Category 5 cable, Category 6, and Category 6a.
Cables in higher categories are designed and constructed to support higher data rates. As new gigabit speed Ethernet technologies are being developed and adopted, Category 5e is now the minimally acceptable cable type, with Category 6 being the recommended type for new building installations.
Figure 30-16 shows three categories of UTP cable: - Category 3 was originally used for voice communication over voice lines, but later used for data transmission.
- Category 5 and 5e is used for data transmission. Category 5 supports 100Mbps and Category 5e supports 1000 Mbps
- Category 6 has an added separator between each wire pair to support higher speeds. Category 6 supports up to 10 Gbps.
- Category 7 also supports 10 Gbps.
- Category 8 supports 40 Gbps.
Some manufacturers are making cables exceeding the TIA/EIA Category 6a specifications and refer to these as Category 7.
Figure 30-16 Categories of UTP
UTP cable is usually terminated with an RJ-45 connector. The TIA/EIA-568 standard describes the wire color codes to pin assignments (pinouts) for Ethernet cables.
As shown in Figure 30-17, the RJ-45 connector is the male component, crimped at the end of the cable.
Figure 30-17 RJ-45 UTP Plugs
The socket, shown in Figure 30-18, is the female component of a network device, wall, cubicle partition outlet, or patch panel. When terminated improperly, each cable is a potential source of physical layer performance degradation.
Figure 30-18 RJ-45 UTP Sockets
Figure 30-19 shows an example of a badly terminated UTP cable. This bad connector has wires that are exposed, untwisted, and not entirely covered by the sheath.
Figure 30-19 Poorly Terminated UTP Cable
Figure 30-20 shows a properly terminated UTP cable. It is a good connector with wires that are untwisted only to the extent necessary to attach the connector.
Figure 30-20 Properly Terminated UTP Cable
Note:
Improper cable termination can impact transmission performance.
Straight-through and Crossover UTP Cables (30.4.3)
Different situations may require UTP cables to be wired according to different wiring conventions. This means that the individual wires in the cable have to be connected in different orders to different sets of pins in the RJ-45 connectors.
The following are the main cable types that are obtained by using specific wiring conventions:
- Ethernet Straight-through — The most common type of networking cable. It is commonly used to interconnect a host to a switch and a switch to a router.
- Ethernet Crossover — A cable used to interconnect similar devices. For example, to connect a switch to a switch, a host to a host, or a router to a router. However, crossover cables are now considered legacy as NICs use medium-dependent interface crossover (auto-MDIX) to automatically detect the cable type and make the internal connection.
Note:
Another type of cable is a rollover cable, which is Cisco proprietary. It is used to connect a workstation to a router or switch console port.
Using a crossover or straight-through cable incorrectly between devices may not damage the devices, but connectivity and communication between the devices will not take place. This is a common error and checking that the device connections are correct should be the first troubleshooting action if connectivity is not achieved.
Figure 30-21 identifies the individual wire pairs for the T568A and T568B standards.
Figure 30-21 T568A and T568B Standards
Table 30-2 shows the UTP cable type, related standards, and typical application of these cables.
Table 30-2 Cable Types and Standards
Activity – Cable Pinouts (30.4.4)
For this activity, correctly order the wire colors to a TIA/EIA cable pinout. Select a wire case color by clicking it. Then click a wire to apply that casing to it.
Refer to the online course to complete this Activity.