Ethernet is one of the most popular standards for connecting PCs to form a Local Area Network (LAN). Most ethernet systems are able to operate at upto 10 megabits per seconds (mbps), and newer systems are designed for 100 mbps speed. Ethernet defines both the types of network cable to be employed, and the signal levels and frequencies used.
Ethernet Cabling Systems
There are 4 commonly used Ethernet cabling systems, which are listed below:
High-Speed Networking
High speed networking designs are motivated by the limitations of existing network topologies. The basic concept has been to simply increase the data rate of the network. For example, 10-Mbit/sec Ethernet was improved tenfold with the standardization of Fast Ethernet (100 Mbits/sec). For technical reasons, increasing the data rate reduces the maximum station-to-station distance, so alternative schemes such as FDDI (Fiber Distributed Data Interface) are often employed as a backbone technology when long distance and high data rate are required, such as in campus environments. Fast Ethernet can fulfill backbone requirements as long as the network is usually within the confines of a single building.
The typical strategy is to connect servers to backbone, where they can take advantage of the higher throughput. For example, a server connected to a 100-Mbit/sec backbone can simultaneously handle ten clients operating at 10 Mbits/sec with ease.
Pusing the bandwidth even further is Gigabit Ethernet, which operates at a data rare of 1,000 Mbits/sec. Its primary purpose is for use in network backbone or as a replacement for existing 100-Mbit/sec switches.
Still,pumping up the bandwidth is not always a complete solution. While Gigabit Ethrnet can improve backbone performance, local network traffic may still suffer from bottlenecks due to the shared nature of the LANs or the collisions caused under heavy traffic loads on Ethernet networks. Switching and Virtual Private Networking can provide a solution.
Related Ethernet Reads:
Ethernet is the most widely used and installed LAN technology. Now specified in a standard, IEEE 8019.3, Ethernet was originally developed by Xerox and then developed further by Xerox, DEC, and Intel.
Installation:
An Ethernet LAN installation typically uses coaxial cable or special grades of twisted pair wires. The most commonly installed Ethernet systems are called 10BASE-T and provide transmission speeds upto 10Mbps.
The Access method used By Ethernet is CSMA/CD. Devices are connected to the cable and compete for access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol.
Topology
Early ethernet systems used a thick (about half a inch) coaxial cable which was tapped at intervals to send smaller cables to each computer. A popular development was the use of 'thin' cables looped to each computer in the system (Example of Ring Topology). A problem with this approach was that if the cable was broken at any point (and it often has to be, to allow computers to be moved) the whole system stopped working. The modern replacement or alternative for 'thin' ethernet is UTP (unscreened twisted pair). The network cable is a twisted pair of wires, connected using phone-type plugs and sockets. UTP systems require a hub, into which all the cables are connected.
In practice, the cable is still a chain between computers like the earlier thin wire, but the hub is able to deal with a cable being disconnected by re-routing internally. This makes the system more reliable, and tidier, in use.
Peer System
Ethernet is a peer system, i.e., all computers on the system have equal (networking) status. There is no 'master' unit which is responsible for deciding whose turn it is to transmit. Some means has to be found to ensure that two units do not try to transmit at the same time. The scheme adopted is called CSMA-CD, carrier sense, multiple access with collision detection. Carrier sense multiple access means that if it wants to transmit, a computer must check that no other unit is doing so. if the line is free, it starts transmission immediately, otherwise it waits before trying again.
Access Method (CSMA-CD):
Ethernet uses the CSMA/CD access method to share network media. The CSMA/CD protocol can be broken down as follows:
- CS (Carrier Sense) Before trnasmitting, listen for a signal; if none is found, it is okay to transmit.
- MA (Multiple Access) All computers share the same cable and signalling techniques.
- CD (Collission Detection) Detect collisions, wait, and retransmit.
There are 4 commonly used Ethernet cabling systems, which are listed below:
| Cable | description |
| 10Base5 | Also Known as RG-8 or Thicknet coaxial cable: carries signals up to 500 meters (1640 feet) at 50 ohms |
| 10Base2 | Also known as RG-58 or Thinnet coaxial cable; carries signals upto 185 meters (607 feet) at 50 ohms. |
| 10BaseT | Also known as twisted-pair; the most popular of all Ethernet Topologies, categories include 3.5, and 6 (UTP, or unshielded twisted pair) cable at up to 100Mbps speeds; carries signals up to 100 meters (330 feet) |
| 100BaseT | Also Known as twisted-pair: uses category 5 for speeds upto 100Mbps and category 6 for speed upto 155 Mbps; carries signals up to 100 meters(330 ft) |
High-Speed Networking
High speed networking designs are motivated by the limitations of existing network topologies. The basic concept has been to simply increase the data rate of the network. For example, 10-Mbit/sec Ethernet was improved tenfold with the standardization of Fast Ethernet (100 Mbits/sec). For technical reasons, increasing the data rate reduces the maximum station-to-station distance, so alternative schemes such as FDDI (Fiber Distributed Data Interface) are often employed as a backbone technology when long distance and high data rate are required, such as in campus environments. Fast Ethernet can fulfill backbone requirements as long as the network is usually within the confines of a single building.
The typical strategy is to connect servers to backbone, where they can take advantage of the higher throughput. For example, a server connected to a 100-Mbit/sec backbone can simultaneously handle ten clients operating at 10 Mbits/sec with ease.
Pusing the bandwidth even further is Gigabit Ethernet, which operates at a data rare of 1,000 Mbits/sec. Its primary purpose is for use in network backbone or as a replacement for existing 100-Mbit/sec switches.
Still,pumping up the bandwidth is not always a complete solution. While Gigabit Ethrnet can improve backbone performance, local network traffic may still suffer from bottlenecks due to the shared nature of the LANs or the collisions caused under heavy traffic loads on Ethernet networks. Switching and Virtual Private Networking can provide a solution.
Related Ethernet Reads:
- Gigabit Ethernet or Fast Ethernet.
- FDDI (Fibre Distributed Data Interface).
Ethernet is mainly using for one to one connection and establish a good connectivity between devices.
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