Coaxial cable – was used on networks in the olden days, however today’s networks moved on to faster and tougher cables. This is not to say that coaxial cables will no longer be encountered as some networks that used this type of cable might still do so because their environment is still the same and so they feel that there’s no need to upgrade.
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The above figure shows an example of a coaxial cable, which looks similar to the cables used for TVs.
There are two types of this cable Thick and Thin coaxial, although the two are no longer popular; out of the two thin coaxial is more popular. It’s about 0.25 inches in diameter and has a max length of about 185 meters and they use the BNC connector.
Continue reading 3. Media and Connectors Part 2
68A and 568B Standard
The Telecommunications Industry Association (TIA) and the Electronics Industry Association (EIA) have designed a wiring standard called 568A and 568B, which is used for the RJ-45 connectors on a UTP/STP cable. The number 568 refers to the order the wires within the Cat 5, Cat 3 and Cat 6 cables are terminated and attached to the connector. Both standards (568A and 568B) are the same in terms of the signal with a slight difference in the order the pins are terminated. They’re both used for patch cords in Ethernet networks. To be able to make these cables (in case you have to) you need to know which order to connect the wires to the connector. The following figure illustrates this, the pin numbers are read left to right while the connector tab facing down.
Administrators must have solid knowledge of the logical standards and the physical media used on today’s networks.
Logical standards define the characteristics such as the configuration of the network, the speed at which they operate and how devices access the network.
Physical media refers to the cabling and connectors used to create the network.
The above two define and dictate the maximum distance between devices, the capability of media to withstand outside interference and even how much space is required in wiring closets and equipment cabinets. Choosing the correct media is very important because they form the foundation for the entire network.
When working with any media, you must be aware of the factors that influence its suitability for a given network implementation.
Interference, transmission speed, media length and installation and repair are some of the most common factors that affect media.
Media Interference (EMI) – common sources of EMI (electromagnetic Interference) are:
- Computer Monitors.
- Fluorescent light fixtures.
- Basically anything that creates an electromagnetic field.
Continue reading 2. Media and Connectors
A network can be any connected devices. It can be as small as two computers or as complex as a multisite network such as a telecommunications infrastructure that contains 100s if not 1000s of computers that are connected together.
The common uses of a network are:
- Communication – video conferencing, email, chats, learning, etc…
- Sharing Hardware – printers, scanners, storage…
- Sharing data – files.
- Sharing applications – Microsoft word, spread sheet, specialised software, etc.
- Data Backup and retrieval
1.1 Types of Networks
1.1.1 LANs and WANs
They types of network used are dictated by the number of locations they span.
LANs – Local Area Networks are restricted to a single location (building, office, school).
WANs – Wide Area Networks spread over multiple geographic locations. They are slower than LANs and more expensive and they tend to use different technologies to connect LANs together to create an internetwork.
Continue reading 1. Introduction to Computer Networks