Lectures notes for 2010 - KTH

Long Fat Pipes
Networks with large bandwidth-delay products are called Long Fat Networks
(LFNs) - pronounced “elefants”.
TCP running over a LFN is a Long Fat Pipe.
• Window Scale option - to avoid 16 bit window size limit
• Timestamp option - putting a time stamp in each segment allows better
computation of RTT
• Protection Against Wrapped Sequence Numbers (PAWS) - with large
windows you could have sequence number wrap around and not know
which instance of a given sequence number is the correct one;
solved by using timestamps (which must simply be monotonic)
• T/TCP - TCP extension for Transactions; to avoid the three way
handshake on connection setup and shorten the TIME_WAIT state.
(for details of T/TCP see Stevens, Vol.3)
Maguire TCP header continued 5: 35 of 77
maguire@kth.se 2010.03.21 Internetworking/Internetteknik