TCP Header Fields
transport services access point (TSAP)
- IP address (=NSAP address) + port # are TCP/ IP source & destination addresses
- ATM-SAPs (service access points) in ATM
flags
- URG=1 if urgent pointer (offset) in use
- ACK=1 means ack present, ACK# is expected
- PSH=1 means push out to port before assembly
- RST for reset, problem has occurred
- SYN & ACK for connection request or accepted
- FIN to relase connection
window says how many bytes may be open