Ethernet computer network cable frequently asked questions answered

Ethernet computer network cableYou will often hear a common computer network patch cable called an "Ethernet cable." While most modern local area networks (LAN) use the same type of cable, the term Ethernet is a family of computer networking technologies that defines how the information flows through the wire, but does not define the physical network cable.

The standards defining the physical layer of wired Ethernet are known as IEEE 802.3, which is part of a larger set of standards by the Institute of Electrical and Electronics Engineers Standards Association.

Cable types, connector types and cabling topologies are defined by TIA/EIA-568, a set of telecommunications standards from the Telecommunications Industry Association (TIA). The standards address commercial building cabling for telecommunications products and services.

Computer network cabling

Twisted Pair Cabling is a common form of wiring in which two conductors are wound around each other for the purposes of canceling out electromagnetic interference which can cause crosstalk. The number of twists per meter make up part of the specification for a given type of cable.

 Unshielded twisted pair (UTP) cableThe two major types of twisted-pair cabling are unshielded twisted-pair (UTP) and shielded twisted-pair (STP). In shielded twisted-pair (STP) the inner wires are encased in a sheath of foil or braided wire mesh. Unshielded twisted pair (UTP) cable is the most common cable used in modern computer networking.

What does Cat5 Cable mean?

A Category 5 cable (Cat5 cable) is made up of four twisted-pair wires, certified to transmit data up to 100 Mbps. Category 5 cable is used extensively in Ethernet connections in local networks, as well as telephony and other data transmissions.

Cat5 Cable has been the standard for homes and small offices for many years. As technology for twisted pair copper cabling has progressed, successive categories have given buyers more choices. Category 5e and Category 6 cable offer more potential for bandwidth and better potential handling of signal noise or loss. Newer cable types also help to deal with the issue of cross talk or signal bleeding, which can be problems with unshielded twisted pair cabling.

The category 5e specification improves upon the category 5 specification by revising and introducing new specifications to further mitigate the amount of crosstalk.The bandwidth (100 MHz) and physical construction are the same between the two.

The category 6 specification improves upon the category 5e specification by improving frequency response and further reducing crosstalk. The improved performance of Cat 6 provides 250 MHz bandwidth and supports 10GBASE-T (10-Gigabit Ethernet). The Cat 6 cable is fully backward compatible with previous versions, such as the Category 5/5e

Older versions of voice and data cable

Category 1 Traditional UTP telephone cable can transmit voice signals but not data. Most telephone cable installed prior to 1983 is Category 1. Category 2 UTP cable is made up of four twisted-pair wires, certified for transmitting data up to 4 Mbps. Official TIA/EIA-568 standards have only been established for cables of Category 3 ratings or above.

Category 3 was widely used in computer networking in the early 1990s for 10BASE-T. In many common names for Ethernet standards the leading number (10 in 10BASE-T) refers to the transmission speed in Mbit/s. BASE denotes that baseband transmission is used. The T designates twisted pair cable.

Category 4 cable consists of four unshielded twisted-pair (UTP) copper wires used in telephone networks which can transmit voice and data up to 16 Mbit/s. Category 4 cable is not recognized by the current version of the TIA/EIA-568 data cabling standards.

What does Patch Cable mean?

A patch cord, also called a patch cable, is a length of cable with connectors on each end that is used to connect one electronic device to another. In computer networking what people often call an “Ethernet Cable” is Unshielded Twisted-Pair (UTP) patch cable.

What does Straight-Through Cable mean?

What is a Crossover CableA straight-through cable is a standard patch cable used in local area networks. Straight-through cables have the wired pins on one end match on the other end. In other words, pin 1 on one end is connected to pin 1 on the other end, and the order follows the straight through route from pin 1 through pin 8.

What is a Crossover Cable?

A crossover cable is used for the interconnection of two similar devices. It is enabled by reversing the transmission and receiving pins at both ends, so that output from one computer becomes input to the other, and vice versa. The reversing or swapping of cables varies, depending on the different network environments and devices in use.

This type of cable is also sometimes called a and is an alternative to wireless connections where one or more computers access a router through a wireless signal. Use a straight-through cable when connecting a router to a hub, a computer to a switch, or connecting a LAN port to a switch, hub, or computer.

Why do you need a crossover cable?

A traditional port found in a computer NIC (network interface card) is called a media-dependent interface (MDI). A a traditional port found on an Ethernet switch is called a media-dependent interface crossover (MDIX), which reverses the transmit and receive pairs. However, if you want to interconnect two switches, where both switch ports used for the interconnection were MDIX ports, the cable would need to be a crossover cable.

Introduced in 1998, Auto MDI-X made the distinction between uplink and normal ports and manual selector switches on older hubs and switches obsolete. Auto MDI-X automatically detects the required cable connection type and configures the connection appropriately, removing the need for crossover cables.

Gigabit and faster Ethernet links over twisted pair cable use all four cable pairs for simultaneous transmission in both directions. For this reason, there are no dedicated transmit and receive pairs, and consequently, crossover cables are never required.