Computer Networking - TCP

[Segment Format] If set, this segment cumulatively ACKs all data bytes up to, but not including, the byte index in the ACK value field of this segment.

ACK bit

[Segment Format] This field contains the index in the byte stream of the next in-order byte expected at the receiver

ACK number field

[Segment Format] This field contains the Internet checksum of the TCP segment and selected fields in the IP datagram header.

Checksum

[Segment Format] This field contains application data that was written into a socket by the sender of this TCP segment.

Data (or payload)

[Segment Format] This field contains the number of available bytes in the TCP receiver's buffer.

Receiver advertised window

[Segment Format] This field contains the index in the sender-to-receiver byte stream of the first byte of that data in the payload carried in this segment.

Sequence number

[Segment Format] This field contains the port number associated with the sending socket for this TCP segment.

Source port number

[Segment Format] This field contains the number of bytes in the TCP header.

Header length field