TCP
TCP is a connection-oriented transport protocol that sends data as an unstructured stream of bytes. By using sequence numbers and acknowledgment messages, TCP can provide a sending node with delivery information about packets transmitted to a destination node. Where data has been lost in transit from source to destination, TCP can retransmit the data until either a timeout condition is reached or until successful delivery has been achieved. TCP can also recognize duplicate messages and will discard them appropriately. If the sending computer is transmitting too fast for the receiving computer, TCP can employ flow control mechanisms to slow data transfer. TCP can also communicates delivery information to the upper-layer protocols and applications it supports. All these characteristics makes TCP an end-to-end reliable transport protocol. TCP is specified in RFC 793 
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Figure 1 – TCP/IP Protocol Suite in Relation to the OSI Reference Model
Some good referecnce:-
http://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13769-5.html#tcp
http://www.tcpipguide.com/free/t_IPDatagramGeneralFormat.htm
https://www.redbooks.ibm.com/redbooks/pdfs/gg243376.pdf
HtH
regards
Inayath
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