What is the Frame Structure, Operation and Collisions of IEEE802,3 Protocols?

The ‘IEEE802, 3' protocol refers to Ethernet, typically belonging to the family of Local Area Network (LAN). The type of network was developed by Xerox and standardised as the IEEE802, 3. The IEEE802, 3 describes all Ethernet based networks 10, 100 and 1000 Mbps. The Ethernet's system frame structure consists of three basic elements:

1. The physical medium used to carry Ethernet signals between computers.
2. A set of access control rules embedded in each Ethernet interface that allows multiple computers to arbitrate access to the shared Ethernet channel.
3. An Ethernet frame that consists of a standard set of bits used to carry data over the system.

When a machine is to send data the station first listens to the channel, and when the channel is idle the station transmits its data in the form of an Ethernet frame or packet. After each frame transmission; all stations on the network must contend equally for the next transmission opportunity. Access to the shared channel is determined by the MAC (Medium Access Control) mechanism embedded in the Ethernet interface located in each station. A node is either transmitting or receiving at any instant; where the data is broken into packets and each one is transmitted using the Carrier Sense Multiple Access with Collision Detection algorithm until it arrives at its destination.

The way Ethernet deals with collisions is by the medium access control mechanism which is based on a system called CSMA/CD (Carrier Sense Multiple Access with Collision Detection). The CSMA/CD is a low level advanced protocol that detects collisions. It's used for when two nodes transmit at once and the data becomes corrupted, this is detected and the nodes continue to transmit so all other nodes on the system can detect the collision. The nodes then wait for a random time (also dependent on the network bandwidth) before attempting to transmit again thus minimising the chances of another collision. The ability to detect transmissions minimises the amount of bandwidth wasted on collisions.