The document describes the structure of a TCP segment, including the fields for source port, destination port, sequence number, acknowledgment number, header length, flags, receive window, checksum, urgent data pointer, and application data. It provides an example TCP segment containing the text "hello world!" to demonstrate the various fields.

1. Transport Layer/TCP
Thanks to Kai Shen’s Networking Course at the University of Rochester.

2. TCP Segment Structure

3. 3a 98 05 cb
fd d3 08 27
27 ed de 7d
50 18 fc 00
be 68 00 00
68 00 65 00
6c 00 6c 00
6f 00 20 00
77 00 6f 00
72 00 6c 00
64 00 21 00
Bytes in TCP
Segment:
source port:
destination port:
sequence number:
acknowledgment number:
urgent: push:
reset: synch:
finish:
checksum:
urgent data pointer:
application data:

4. 3a 98 05 cb
fd d3 08 27
27 ed de 7d
50 18 fc 00
be 68 00 00
68 00 65 00
6c 00 6c 00
6f 00 20 00
77 00 6f 00
72 00 6c 00
64 00 21 00
Source Port (0x3a98): 15000
Destination Port (0x05cb): 1483
Sequence Number (0xfdd30827): 4258465831
Acknowledgment Number (0x27edde7d): 669900413
Header Length (upper 4 bits is # words 0x5): 5 words or 20 bytes
Flags (0x18): 0001 1000
Receive Window (0xfc00): 64512
Checksum (0xbe68): Correct
Urgent Data Pointer (0x0000): Not Used
Data (68 00 65 00 6c 00 6c 00 6f 00 20 00 77 00 6f 00 6c 00 64 00 21 00):
hello world!
Bytes in TCP
Segment:

8. PureAverageRTT

9. TCP State Transition Diagram
Server Client