Overview

• Unlike UDP, TCP’s sessions are explicitly established and terminated

• • 3 messages for connection establishment
  • 4 messages for connection termination
  • All these control packets contain no TCP data

• TCP’s connection establishment allows the two hosts to

• • Exchange capabilities
  • • Capabilities appear in TCP options
  • Initialize sequence numbers
  • • Initial sequence numbers are derived from an internal counter that is incremented by roughly 128,000 every second

• Connection termination allows each host to inform the other that they are done sending data

• • Both hosts need not terminate the connection simultaneously