Subject: Re: [Tsvwg] Re: new I-D for SACK-based recovery

From: Mark Allman <[email-masked]>
Date: Mon, 18 Dec 2000 23:26:51 -0500

> My gut feeling is that you can send precisely the number of bytes
> that were ACKed...  This may or may not be one segment, I suppose.
> Perhaps this needs clarification?
> 
> Mark, any feelings on this?

Hmm... My first hit is that you're right, I guess.  Although, I am
not sure we send *precisle* the number of bytes possible.  I would
say we would want to send the greatest number of full-sized segments
possible (i.e., there could -- in theory -- be some slop and we
could end up starting to create runt packets this way I think).  I
think that when we receive every ACK that this means we'll send one
segment in response to each ACK).  However, if we lose an ACK we'll
get more new SACK information on the subsequent ACK and therefore
there is a chance we could squeeze out more than one segment, which
is probably the right thing to do.  (And, this likely prevents some
small burst at the end of recovery if we have a bunch of ACK loss).

We should clean this up in the draft, assuming there are no further
objections.

Thanks!

allman

---
Mark Allman -- NASA GRC/BBN -- http://roland.grc.nasa.gov/~mallman/

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From: venkat venkatsubra <[email-masked]>
Date: Tue, 19 Dec 2000 12:52:33 -0600

Mark, Ethan,
Thanks for the response.
When retransmitting after the third duplicate ACK, should
the retransmitted packet be added to the ``pipe'' or not ?
The algorithm does not add it.
Thanks!
Venkat

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From: Murali Bashyam <[email-masked]>
Date: Tue, 19 Dec 2000 12:26:44 -0800 (PST)

> The algorithm does not add it.

Isn't it already accounted for in the setting of pipe to
	HighData - HighACK - AmountSACKed ?

The fast retransmit is going to send HighACK, isn't it?

Murali

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From: Murali Bashyam <[email-masked]>
Date: Tue, 19 Dec 2000 12:49:31 -0800 (PST)

Shouldn't there be a call to MarkRetran in step D, in the scenario
when NextSeg returns a sequence number corresponding to a previously
sent segment?

Murali

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From: Ethan Blanton <[email-masked]>
Date: Tue, 19 Dec 2000 15:56:03 -0500

> when NextSeg returns a sequence number corresponding to a previously

You are absolutely correct.  Consider it added.
Ethan

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