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Dated: May. 09, 2012
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Something About Cables
In any wired LAN environment it becomes necessary to take utmost care while selecting cables for the network setup. Engineers and administrators may select cable types according to the requirements of the LAN setup, budget involved in the infrastructure installation and the scalability of the network. Since cables play important role in any wired network infrastructure it becomes important for the administrators and engineers to select appropriate cable types so as to meet and fulfill the requirements of the organizations.
Any one among the three available types of cables can be used in order to establish a complete wired network infrastructure. The cable types that can be used are:
- Coaxial Cables – These cables are no longer used in any network infrastructure today as they are obsolete. In earlier days these cables were used and they were available in two categories, namely 10Base2 and 10Base5. In these naming conventions, 10 represented the speed in Mbps or Megabits Per Second at which data transferred on the cables which was 10 Mbps, the term Base indicated that the cables were meant to be used for a baseband connection and 2 and 5 at the end of the names represented that the data could travel up to 185 meters and 500 meters respectively at a single cable segment. This means that the distance between two directly connected computers can be up to 185 meters (when using 10Base2) and 500 meters (when using 10Base5) using a single segment of a cable without using any repeater or signal amplifier.
- Twisted Pair Cables – These cables are mostly used nowadays and are preferred by almost all network administrators and engineers in most small, medium and large-scale organizations. Since twisted pair cables are quite cost-effective and easy to install, they are the most demanded cables in any IT oriented organization. Twisted pair cables are further divided into two categories, namely Unshielded Twisted Pair (UTP) and Shielded Twisted Pair (STP). UTP cables are mostly used in organizations because they are much cheaper as compared to STP cables.
- Fiber Optic Cables – These cable types are the most expensive ones and are mostly used by Internet Service Providers (ISPs). Data in these cables does not flow in the form of current but in the form of light. Because of this reason, the attenuation (tendency of signals getting weak because of resistance) of data signals is highly reduced while using fiber optic cables. Moreover, fiber optic cables allow data to transmit at the distance of 2 KM – 50 KM, depending on the type of cable used. One of the biggest advantages that fiber optic cables have over copper cables is that the data signals that fiber optic cables transmit are not affected by electromagnetic interference (EMI) and therefore fiber optic cables can be installed even near very high electric voltage areas. With the help of fiber optic cables chances of cross-talks are also reduced to almost 0%. Separate types of connectors are used for fiber optic cables which can be hard to crimp. Fiber optic cables cannot be bent for more than 60° during installation as the cables might not transmit the data (which is in the form of light) appropriately in such cases. The reason behind this is that since fiber optic cables have glass coating and the data travels over the cables because of reflection, bending the cables at more than 60° angle might obstruct the transmission of reflected signals.
Naming Conventions Used for UTP Cables
Many times UTP cables are also known by the term Category followed by a specific number that represents the type of that particular UTP cable. For example, Category 5 is a form of UTP cable that is also referred as 100BaseT. Sometimes Category 5 cables are also called Cat 5 cables. Terms like 100BaseT, Category 5 and Cat 5 are used interchangeably.
The above specifications are just an example of one type of cable that is used in LAN environment. There are some more UTP cable categories that are used to establish a complete and efficient wired network setup. Some of the most commonly used UTP cable types are:
- Category 3 or Cat 3 - These types of cables are also referred as 10BaseT cables which means that the cables can transfer data at 10 Mbps on twisted pairs (copper wires) and cables must be used for baseband connections. Data transmitted over 10BaseT cables can travel up to 100 meters without any amplifying device or repeater. These types of cables are no longer in use however central devices that support 10 Mbps LAN ports are still available in the market for backward compatibility. Cat 3 cables are mostly used in physical star topology. Networks that use Cat 3 cables are generally referred as Ethernet networks.
- Category 4 or Cat 4 – These cable types were mostly used in Token Rings in Ring Topologies where data was transmitted at 16 Mbps. Since Token Ring topologies used Ring topologies and the lifespan of Ring Topologies was quite brief, the existence of Cat 4 did not last long.
- Category 5 or Cat 5 – These cable types are also known as 100BaseT which means that the data that the cables transfer is transmitted at the speed of 100 Mbps on baseband connections using twisted pairs. The distance that the data covers on a single segment of Cat 5 cable is 100 meters. The network communication that takes place using Cat 5 is generally referred as Fast Ethernet. In the late 90s and early 2000s Cat 5 cables were mostly in demand and almost every network setup that was established during that period still uses 100BaseT cables.
- Category 5e or Cat 5e – These cable types are considered extended versions of 100BaseT. Both Cat 5 and Cat 5e cable types have identical features but they may vary when it comes to the distance at which the data is transferred. The network communication that takes place over Cat 5e is referred as Fast Ethernet. As mentioned earlier, data travels up to 100 meters over Cat 5 cables whereas the data may travel up 400 meters over Cat 5e cables. The exact distance on the later cable type is yet not defined as there are different specifications and theories given by different experts.
- Category 6 or Cat 6 – These cables are also known as 1000BaseT or Gb Ethernet that allow data to be transferred at the speed of 1000 Mbps or 1 Gbps on baseband connections over twisted pairs of copper cables. The distance at which the data travels on Cat 6 cables is 100 meters per segment. The network communication that takes place over Cat 6 cables is referred as GbEthernet or Gigabit Ethernet. These cable types are getting popular nowadays and almost all newly established wired network setups prefer installing Cat 6 cables for better scalability.
Points to Keep in Mind
- Almost all cable types discussed above use two pairs of cables twisted with each other (twisted pairs) in order to reduce cross-talks.
- The term baseband specifies that the cables must be used for Ethernet communications only.
- Ethernet communication that takes place over twisted pairs is standardized as IEEE 802.3.
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