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LAN Networks

by:TBT     2020-08-13
LAN networks have come quite a long way since the early days of networking. There have been a variety of topologies used in LAN. As network topology has evolved, the speed with which data is transmitted, called data rate, has increased.
Different network topologies have used different types of cables and connectors to transmit data across it. LAN networks can be either wired or wireless.
Network Topologies Have Evolved Over the years
Today's networks use either fiber optic cable or four twisted pairs of 22 gauge wire to transmit data, but not terribly long ago, Token Ring (Introduced by IBM), used coaxial cable to connect all of the computers on a network. In this type, the cable left the main computer (server) room and travelled to each workstation and client before returning to the main computer room.
If one computer's connection was lost, the whole network goes down. This was the main reason for the development and adoption of Ethernet-based networks, which make use of the aforementioned 4 twisted pairs of copper wire. In this type of LAN, each workstation is served by a dedicated link to the network and if one computer's connection is lost, the rest of the stay up. Ethernet-based networks have evolved from 10 Base 2 through the current standard, 10 Gigabit Ethernet standard.
Data Rates Continue to Increase in LAN Networks
Today's networks operate at speeds that network specialists from years ago could only dream of. Category 6 and 7 Ethernet network cabling offers speeds up to 10 Gigabits over four twisted pairs of copper wire, while fiber optic cable offer speeds much higher than that for LAN networks. The old network standard (Token Ring) was capable of transmitting data at between four and sixteen Megabits.
While the older Ethernet-based networks weren't always capable of speeds that matched Token Ring, the increased reliability they gave more than made up for the lost throughput. More and more corporate networks are being transitioned to fiber optic cable from end to end, with the speeds this type of network cabling is capable of being dependent of the transceivers being used, but Terabit fiber optic networks are not uncommon.
Types of Cables and Connectors Used in LAN Networks Have Changed Since the First Networks
As stated, IBM's Token Ring networks used a coaxial cable to connect all of the computers on a network in a ring. This coaxial cable was normally rated at 58 Ohm resistance and terminated with BNC connectors. Ethernet-based networks use a copper wire that consists of four separate twisted pairs of 22 gauge wires, with each individual 22 gauge wire being an individual conductor. These conductors are grouped into four pairs, blue, orange, green, and brown, with each primary color (tip) being paired with a conductor that has a white insulator with bands that match the primary color (ring). Ethernet cables are connected using RJ-45 connectors. There are a large number of connector types in use with fiber optic cables however the SC, ST, LC, and FC connector types are the most popular.
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