TCP: Transmission Control Protocol

  TCP and UDP use the same network layer(IP),TCP provides a connection oriented,reliable,byte stream service.The term

connection-oriented means the two applications using TCP must establish a TCP sonnection with each other before they

can exchange data.

TCP provides realiability by doing the following:

   (1):The application data is broken into what TCP considersthe best sized chunks to be send.The unit of information passed

by TCP to IP is called a segment.

          This is totally different from UDP,where each write by the application generates a UDP datagram of that size.

   (2):When TCP sends a segment it maintains a timer,waiting for the other end to acknoeledge reception of the segment.

If an acknowledgement isn't received in time,the segment is retransmitted.

   (3):When TCP receives data from the other end of the connection,it sends an acknowledgement.This acknowledge

normally delayed a fraction of a second.

   (4):TCP maintains a checksum on its header and data.If a segment arrives with an invalid checksum,TCP discard it and

doesn't acknowledge receiving it.

   (5):Since TCP segments are transmitted as IP datagrams,and since IP datagrams can arrive out of order,TCP segment

can arrive out of order.

   (6):Sinace IP datagrams can get duplicated,a receiving TCP must discard duplicate data.

TCP also provides flow control.Each end of a TCP connection has a finite amount of buffer sapce.

 

to  be continue...