Page 129 - Handout Computer Network.

Computer Network 2026

TCP is responsible for breaking messages into segments, reassembling them at the
destination station, resending anything that is not received, and reassembling messages from
the segments. TCP supplies a virtual circuit between end-user applications.

These protocols use TCP:

• File Transfer Protocol (FTP)

• Hypertext Transfer Protocol (HTTP)

• Simple Mail Transfer Protocol (SMTP)

• Domain Name System (DNS) Figure 6-3 shown a TCP Segment Format shows the
TCP segment format.

Figure 6-3 shown a TCP Segment Format

The following list defines the fields in the TCP segment, as shown Figure 6-3:

• Source Port—Number of the calling port

• Destination Port—Number of the called port

• Sequence Number—Number used to ensure correct sequencing of the arriving
data
• Acknowledgment Number—Next expected TCP octet

• HLEN—Number of 32-bit words in the header

• Reserved—Set to 0

• Code Bits—Control functions (such as setup and termination of a session)

• Window—Number of octets that the sender is willing to accept

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