netdev - Re: [PATCH 2/2] tcp: TLP loss detection.

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Date:	Mon, 11 Mar 2013 17:38:12 -0400
From:	Neal Cardwell <ncardwell@...gle.com>
To:	Nandita Dukkipati <nanditad@...gle.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Yuchung Cheng <ycheng@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Netdev <netdev@...r.kernel.org>,
	Ilpo Jarvinen <ilpo.jarvinen@...helsinki.fi>,
	Tom Herbert <therbert@...gle.com>
Subject: Re: [PATCH 2/2] tcp: TLP loss detection.

On Mon, Mar 11, 2013 at 4:00 PM, Nandita Dukkipati <nanditad@...gle.com> wrote:
> This is the second of the TLP patch series; it augments the basic TLP
> algorithm with a loss detection scheme.
>
> This patch implements a mechanism for loss detection when a Tail
> loss probe retransmission plugs a hole thereby masking packet loss
> from the sender. The loss detection algorithm relies on counting
> TLP dupacks as outlined in Sec. 3 of:
> http://tools.ietf.org/html/draft-dukkipati-tcpm-tcp-loss-probe-01
>
> The basic idea is: Sender keeps track of TLP "episode" upon
> retransmission of a TLP packet. An episode ends when the sender receives
> an ACK above the SND.NXT (tracked by tlp_high_seq) at the time of the
> episode. We want to make sure that before the episode ends the sender
> receives a "TLP dupack", indicating that the TLP retransmission was
> unnecessary, so there was no loss/hole that needed plugging. If the
> sender gets no TLP dupack before the end of the episode, then it reduces
> ssthresh and the congestion window, because the TLP packet arriving at
> the receiver probably plugged a hole.
>
> Signed-off-by: Nandita Dukkipati <nanditad@...gle.com>

Acked-by: Neal Cardwell <ncardwell@...gle.com>

neal
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