WHAT IS ETHERNET ?

The Ethernet is standardized by the IEEE as 802.3 standard. In Ethernet twisted pair cable and fibre optical cable are mostly used.but co-axial cables are rarely used or not used.Twisted pair cable are used for small distance and have medium speed and optical fibre cable are used where distance are large and high speed are required. optical fibre are expansive. Ethernet support 100mbps  speed . It uses carrier sense multiple access method for detecting collision.

ETHERNET FRAME:-

  

                           

Preamble describe to device that a frame is coming prepare for synchronization . and if device is still not prepared for synchronization then then a SFD (start frame delimiter) is used that describe this is last chance for synchronization otherwise frame will be missed by you. and after SFD frame start.The frame contain source and destination  MAC address .  and TYPE field contain  the detail about type of protocol. DATA and PADDING contain the payload data padding data is added to make it sufficient length long(46 bytes). FCS (frequency check sequence) contain a 32 bit cyclic redundancy check  which allow detection of corrupted data.

ETHERNET ADDRESS:-

1.  UNICAST ADDRESS:-

IN LAN if we want to send data to a specific device then UNICAST address are used.

2.  MULTICAST ADDRESS:-

If we want to send frame to a specific group of devices then we need to sent frame through multicast address. multicast address has value 1 in least significant bit of FIRST octet. example 01:00:0C:CC:CC:CC (This is multicast address of CDP.)

3.  BROADCAST ADDRESS:-

If data sent through broadcast address then data reach every device on the lan. the broadcast has all binary 1. ( FFFF.FFFF.FFFF )