netdev - Re: [PATCH v6 net-next 0/2] tcp: Redundant Data Bundling (RDB)

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Message-ID: <78983A17-6B0C-4A11-BE0E-A98FE699D1E3@ifi.uio.no>
Date:	Thu, 10 Mar 2016 01:45:00 +0000
From:	Jonas Markussen <jonassm@....uio.no>
To:	Yuchung Cheng <ycheng@...gle.com>
CC:	Bendik Rønning Opstad <bro.devel@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	"Eric Dumazet" <eric.dumazet@...il.com>,
	Neal Cardwell <ncardwell@...gle.com>,
	Andreas Petlund <apetlund@...ula.no>,
	Carsten Griwodz <griff@...ula.no>,
	Pål Halvorsen <paalh@...ula.no>,
	Kristian Evensen <kristian.evensen@...il.com>,
	Kenneth Klette Jonassen <kennetkl@....uio.no>
Subject: Re: [PATCH v6 net-next 0/2] tcp: Redundant Data Bundling (RDB)


> On 10 Mar 2016, at 01:20, Yuchung Cheng <ycheng@...gle.com> wrote:
> 
> PS. I don't understand how (old) RDB can masquerade the losses by
> skipping DUPACKs. Perhaps an example helps. Suppose we send 4 packets
> and the last 3 were (s)acked. We perform RDB to send a packet that has
> previous 4 payloads + 1 new byte. The sender still gets the loss
> information?
> 

If I’ve understood you correctly, you’re talking about sending 4 
packets and the first one is lost?

In this case, RDB will not only bundle on the last/new packet but also 
as it sends packet 2 (which will contain 1+2), packet 3 (1+2+3) 
and packet 4 (1+2+3+4). 

So the fact that packet 1 was lost is masqueraded when it is 
recovered by packet 2 and there won’t be any gap in the SACK window
indicating that packet 1 was lost.

Best regards,
Jonas Markussen