Subject: [Tsvwg] TCP send window update

From: "Leah Shalev" <[email-masked]>
Date: Wed, 20 Nov 2002 11:48:49 +0200

Hi,

Probably I am missing something vary basic about the send window update
algorithm (RFC 793).

In particular, I have a question regarding SND.WL2 variable. Apparently it
should be always equal to SND.UNA.
I was trying to figure out when can it be different (to justify its
existence). After a while, I did find one case it can be different: a
retransmitted data segment carries new acknowledge number; SND.UNA is
updated and SND.WND is not updated since SEG.SEQ < SND.WL1. Next second I
started to wonder what is the state of the send window at this point: the
left edge moved, while the window size did not change, so it seems that the
right edge is messed up. So I am back to my original question: why it
should be possible to have SND.WL2 different from SND.UNA.

I would appreciate any help on this.

Thanks,
Leah Shalev

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From: "Amit Jain" <[email-masked]>
Date: Fri, 22 Nov 2002 16:15:57 -0800

I think if SEG.SEQ < SND.WL1 , then SEG.ACK should not be more than SND.UNA (Which may cause SND.UNA to get updated).

I think in most of the scenarion if SEG.ACK > SND.UNA , then SEG.SEQ will be either == SND.WL1 or > SND.WL1.and thus both edge of the window wil be updated.

-amit.

-----Original Message-----
From: Leah Shalev [mailto:[email-masked]]
Sent: Wednesday, November 20, 2002 1:49 AM
To: [email-masked]
Subject: [Tsvwg] TCP send window update

Hi,

Thanks,
Leah Shalev