understand ethernet

Overview:-
1. It is LAN technology
2.It is shared media access method(contentions based)
3.It is originally developed by Dix.(DEC, Intel,xerox).
4.original standards are 10base2 and 10base5.(2means 200m and 5 means 500m cable.)
5.due to cable limitation new standard created by IEEE in 1980.(10baseT).
6.This is popularly known as Ethernet(802.3).
7.Then in the row fast Ethernet (base-TX,802.3u)gigabit Ethernet(1000base LX and SX,802.3z)gigabit Ethernet(1000 base T,802.3ab).
8 .Due to shared nature there may be chances of data collision (crash)
9.TO avoid data crash rule made that is CSMA/CD.
10.This rule force to device to work on half duplex.

Ethernet at Layer 2:-

1.AT layer 2 it divides in two sub layer:-LLC and MAC
2.LLC stands logical link control(802.2)
3.LLC provides communication with upper layer.IT frames the network layer packet.
4.MAC stands for Media access control(802.3).it  does frame delimiting .provides address and also does error detection.
Ethernet at layer 1:-
1.it does not communicate with upper layer.
2.it does not identify devices.
3.only Understand bit streams.
4.Physical standards operate on layer 1.