Lectures notes for 2010 - KTH

Control field - indicates the purpose & contents of this segment:
Flag
URG
ACK
PSH
RST
SYN
FIN
Description
The urgent pointer is valid
The acknowledgement number is valid
Push the data, i.e., the receiver should immediately pass all the data to the application ⇒
emptying the receiver’s buffer
Connection must be rest
Synchronize the sequence numbers
Terminate the connection (from the sender’s point of view)
We will see how these bits are used as we examine each of them later.
The window size (or more exactly the receive window size (rwnd)) - indicates how
many bytes the receiver is prepared to receive (this number is relative to the
acknowledgement number).
Options - as with UDP there can be up to 40 bytes of options (we will cover these
later)
Maguire TCP header continued 5: 8 of 77
maguire@kth.se 2010.03.21 Internetworking/Internetteknik