Title: Physical Media
Course: 2016FA-MCO-110-401 > Section: Module 8: IT Infrastructure

Click here for a downloadable version of this document:(EXTERNAL) Physical Media

While wireless networks are ever present, physical media will always be a requirement of the core network infrastructure. In order for networks to function over large geographical areas, the reduction of interference to the data transfer is an absolute requirement for smooth network operation. Below is a listing of the three most widely utilized physical media in Networking.

Unshielded Twisted Pair - Most commonly referred to as an Ethernet cable, these cables consist of four twisted pairs of insulated wires encased in a single sheath and terminated to an Ethernet adapter. The pairs of wires are twisted for the prevention of attenuation (gradual loss of strength) of a data signal. This allows for transfer of data over longer distances. These cables are commonly rated using a “Category” system which indicates the data transmission speed limit of a particular cable. Three of the most common types of “CAT” cables and their characteristics are illustrated below.

Category 5 – an older, but still utilized cable type limited to 10/100Mbit/second@100Mhz data transfer speed.  Limited to 100 meters of length before interference becomes an issue.

Category 5e – The “e” denotes an “enhanced” performance, and as such, this cable has a useable data transfer speed (throughput) of 1Gbit/sec or 1,000Mbits/second@100Mhz. Limited to 100 meters of length before interference becomes an issue.

Category 6 – A relatively new cable design which greatly improved the speed of Ethernet data transmission. While still utilizing the twisted pair design, it also includes an internal separator of the wire pairs which allows for less attenuation and a higher specific data transfer speed (throughput). CAT6 cables have a rated data transfer speed of 10Gbit/sec or 10,000Mbits/second@250Mhz. For a real world comparison, the maximum throughput of 4GLTE cellular technology is 300Mbits/sec downstream and 75Mbits/sec upstream. Cable Media is Limited to 100 meters of length before interference becomes an issue.

Coaxial Cable – This media type, most commonly used in Cable Television environments, is characterized by a single inner conductor surrounded by a tubular insulated layer then surrounded by a tubular conductive layer and, lastly, surrounded by an insulated outer shield. This type of construction allows for a higher specific throughput as well as usable transmission length. Commonly referred to as a “last mile” technology, it is usually the media of choice utilized by cable providers for connection between the modem and the provider termination point. The actual speed limitation of coaxial cable is more closely related to the number of data channels utilized and the limitations of the transmitting/receiving equipment. This is governed by DOCSIS (Data over Cable Service Interface Specification) standards. For home/business user implementations, the current observed limitation is 400Mbits/sec downstream and 20Mbits/sec upstream.

Fiber Optic – This media type is characterized by the utilization of light pulses to transfer data over optical fibers.

This video was created by PACE-IT, Edmonds Community College and is licensed CC-BY 3.0

This video was created by PACE-IT, Edmonds Community College and is licensed CC-BY 3.0

Objectives met:
- C8
- 8.3
- 8.4