Re: Linux TCP's Robustness to Multipath Packet Reordering

Ilpo Järvinen
2011-06-20T10:42:47Z

On Sun, 19 Jun 2011, Dominik Kaspar wrote:

> Ah... the receiver DSACKs the "original" packet. However, the sender
> already received an ACK for its retransmission and advances SND.UNA.
> When the DSACK finally arrives, it is actually outside of the SND.UNA
> - SND.NXT range, which causes the DSACK to trigger "SACK reneging".
> Did I get that right? :-)

Where did you get this idea of reneging?!? Reneging has nothing to do with
DSACKs, instead it is only detected if the cumulative ACK stops to such
boundary where the _next_ segment is SACKed (i.e., some reason the
receiver "didn't bother" to cumulatively ACK for that too). ...That
certainly does not happen (ever) for out of window DSACKs.

--
i.