|TCP - transmission control protocol|
793 - TCP protocol specification
1122 - TCP additional
1323 - TCP extensions for high performance
2001 - slow start, congestion avoidance, fast retransmit, fast recovery
5681 - TCP congestion control
6298 - TCP retransmission timer
TCP is a reliable host-to-host transport protocol. Higher layer (application) protocols it typically carries are http, ftp, telnet, and others. The network layer protocol that typically carries it is IP.