Subject: [multipathtcp] Clarification concerning window-updates

From: Christoph Paasch <[email-masked]>
Date: Wed, 01 Aug 2012 17:22:32 +0200

Hello,

the draft says in Section 3.3.5:
   The sender remembers receiver window advertisements from the
   receiver.  It should only update its local receive window values when
   the largest sequence number allowed (i.e.  DATA_ACK + receive window)
   increases.  This is important to allow using paths with different
   RTTs, and thus different feedback loops.

However, it does not explicity say that it should only update the receive-
window if a DATA_ACK is in the packet. Because, if he would also accept the 
window-advertisement from packets without DATA_ACK (inferring the DATA_ACK 
from the SND.UNA), he might increase the window although he should not have 
done so.

So, I think the draft should be more explicit here:
The sender MUST NOT update the receive-window if the packet does not contain a 
DATA_ACK.

Cheers,
Christoph

-- 
IP Networking Lab --- http://inl.info.ucl.ac.be
MultiPath TCP in the Linux Kernel --- http://mptcp.info.ucl.ac.be
Université Catholique de Louvain
--