[ee122] Delayed ACK and CWND movement

vern at cs.berkeley.edu vern at cs.berkeley.edu
Mon Nov 5 14:06:20 PST 2007

> Doing the homework, TCP sends data ACK's every other packet it recieves.

Right, though we haven't covered this yet.  (We will in Wednesday's lecture.)

> When I was thinking about the CWND, I got confused as to how much this
> would increase if the ACK's came only after every other packet (i.e.
> half as many ACK's). I would think that the CWND would grow half as
> fast as a result (since upon an ACK, CWND += MSS*(MSS/CWND)).

Indeed it does, if one uses that formulation for congestion avoidance.
Remember that another formulation is to track a packet per flight, and
bump by MSS when it's ack'd - that approach doesn't have this problem.


More information about the ee122 mailing list