IEEE 802 Members

IEEE 802 Members

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The Institute of Electrical and Electronics Engineering (IEEE) is a leading organization in the world. It constituted a task force to set standards for connectivity between NIC and transmission media. This task force is known as the 802 committee. The 802 committee was subdivided into several sub groups and each group is responsible for the implementation of a single standard that specifies the data transfer that occurs at the data link layer of the OSI model. Brief descriptions of these sub groups are described below:

802.1

This standard is responsible for data communication between all seven layers of the OSI model.

802.2

It defines LLC (Logical layer control) sub layer of data link layer that is used by lower layer protocols.

802.3

The 802.3 standard defines Ethernet and the functions related to MAC (medium access control) sub layer of the data link layer. There are different types of transmission media in 802.3.

• 1BASE5: The data transfer rate is 1Mbps and it uses UTP cable with a signal range up to 500 meters. In this standard, star topology is used.
• 10BASE5: It is also known as thick Ethernet and it supports data transfer rate of 10Mbps with a signal range up to 500 meters. In this standard, coaxial thicknet cable is implemented.
• 10 BASE2: It uses thinnet coaxial cable and has the data transfer speed of 10Mbps. In this standard, bus topology is used.
• 10BASE F: It implements fiber optics cable. The data transfer rate is 10Mbps.

Conceived in the 1960s, the Ethernet (802.3) is the oldest and most popular data link layer protocol (or network technology) used in today's networks. Ethernet networks use a bus or star topology and control the flow of data through the media access control (MAC) method known as Carrier Sense Multiple Access Collision Detection (CSMA/CD). The use of CSMA/CD ensures that each computer in a network can send its signals over the network. To send signals over the network, a computer waits for the network to be free of any traffic, if the network is free it sends its signals, which travel through the network and are received by the destination computer. Some times more than one computer sends its signals over the network, which results in collision. Collisions in these types of networks cannot be avoided, as CSMA/CD can detect it only when they occur. It then resends the data over the network again to compensate the data loss.

Ethernet networks run at various speeds, depending on the type of topology and cabling used. Ethernet technology is widely implemented in Star topology using coaxial or fiber optic cables, and in bus topology using UTP cable.

802.4

This defines a network with bus topology that implements media access control with token mechanism.

802.5

This defines a network with ring topology. It uses media access control with token mechanism. It supports data transfer rate of 1,4, and 16 Mbps. Originally developed by IBM, the token ring is an intricate but highly dependable networking technology that follows the IEEE 802.5 standard. The type of topology used in this technology is physically a star, but implemented logically as a ring, in which all the computers are attached to a central unit called a multistation access unit (MAU OR MSAU). Token ring networks use token passing to send their signals over the network. Token is a type of data packet, which circulates in the entire network. If the token is free, the computer waiting to send data takes it, attaches the data and the destination address to the token, and sends it. When the token reaches its destination computer, the data is received. Then, the token gets back to the originator. If the originator finds that the message has been received, it removes the message from the token. Now, the token is free and can be used by the other computers in the network to send data.

Token ring networks are more fault tolerant than the Ethernet, as the MSAU ensures that the failure of a single computer does not bring the entire network down. It is an intelligent device, which identifies the failing computer in the network, and then bypasses it to correct the errors.

The modern day token ring networks use unshielded twisted pair (UTP) cable and run at the speed of 16 Mbps as opposed to the original token ring networks developed by IBM that used shielded twisted pair (STP) cable and ran at 4 or 16 Mbps.

802.6

This describes MAN standard known as Distributed Queue Dual Bus (DQDB). DQDB is designed for data, voice, and video transmission through fiber optics cable. The dual bus topology is employed and traffic on each bus is unidirectional.

802.8

This standard deals with the implementation of fiber optics technology in networking environment.

802.11

The IEEE 802.11 standards define wireless local area network (WLAN) computer communication in the 5GHz and 2.4GHz public spectrum bands. These specifications define an over-the-air interface between a wireless client and a base station or access point. The 802.11 specifications also define standards among wireless clients. These specifications address both the Physical (PHY) and Media Access Control (MAC) layers and are tailored to resolve compatibility issues between manufacturers of wireless LAN equipment.

Apart from these IEEE standards, there is one more standard named FDDI developed by ANSI.

FDDI (Fiber Distributed Data Interface)

Developed by the American National Standards Institute (ANSI), FDDI is a ring-based network that uses fiber optic cables to provide very fast and reliable communication between the connected computers. It uses token passing to control the network access but does not use a hub like the token ring networks; instead, it uses a central device called concentrator to connect the computers in the network. In these networks, the computers are connected using physical ring topology.

There are two types of configurations used by FDDI networks, namely class A and class B configurations. In class A, a double ring topology is used in which the computers are connected to two rings. The signals travel in opposite directions on both the rings. If there is a fault in one ring, the receiving computer can still receive the signal through the other ring. These networks provide a better fault tolerance. Class B networks use a single physical ring and are, therefore, less fault tolerant.

FDDI networks run at the speed of 100 Mbps and, as they use fiber optic cables, provide connectivity over long distances. These networks have now been replaced by Fast Ethernet networks that provide the same speed and are more fault tolerant.

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