July 11, 20178 yr Source Port and Destination Port fields together identify the two local end points of the particular connection. A port plus its hosts' IP address forms a unique end point. Ports are used to communicate with the upper layer and distinguish different application sessions on the host. The Sequence Number and Acknowledgment Number fields specify bytes in the byte stream. The sequence number is used for segment differentiation and is useful for reordering or retransmitting lost segments. The Acknowledgment number is set to the next segment expected. Data offset or TCP header length indicates how many 4-byte words are contained in the TCP header. The Window field indicates how many bytes can be transmitted before an acknowledgment is received. The Checksum field is used to provide extra reliability and security to the TCP segment. The actual user data are included after the end of the header.
Create an account or sign in to comment