Last Call for TCP Congestion Control I-D

[Vern Paxson <[e-mail]>]

The -01 version of the TCP Congestion Control I-D has now come out.
Mark & I feel it's ready for publication as Proposed Standard, so we're
holding a two-week last call for final comments, with the last call ending
on Nov 24.

The main differences between this version and the -00 version are:

	- Changed acking-at-least-every-second-segment from a MUST to
	  a SHOULD.  This reflects the recent discussion on the mailing
	  list that presented arguments why it might indeed sometimes
	  make sense to generate ACKs at a lower rate.  Added a strong
	  caution that this should not be done lightly.

	- Clarified that the receiver doesn't know the true MSS and
	  so the ack-at-least-every-second-full-MSS-segment requirement
	  means in terms of its offered MSS.

	- Added that a TCP receiver SHOULD generate an immediate ACK
	  when an incoming segment fills a gap in the sequence space.
	  This reflects the recent discussion of how failure to do so
	  can lead to miserable performance.

	- Added discussion of "FlightSize", the amount of outstanding
	  data at the time of a loss.  On loss, ssthresh is set to
	  FlightSize/2 (or 2*MSS, whichever's larger).  This used
	  to be "min(cwnd,rwnd)" but it was pointed out that you might
	  have less data in flight than either of those.

	- Removed proposed algorithm for recovering from multiple losses
	  in a single flight, and replaced it with a general discussion
	  of congestion control requirements for loss recovery mechanisms.

	- Added a pointer to draft-ietf-tcpimpl-newreno-00.txt as one
	  example of Reno modifications for dealing with recovering from
	  multiple losses.  This I-D has been sent to the Internet Drafts
	  editor and should be posted shortly.

The next message are context diffs between -00 and -01.

		Vern


ftp://ftp.ietf.org/internet-drafts/draft-ietf-tcpimpl-cong-control-01.txt