Subject: Re: [PATCH net-next v12 3/7] sch_cake: Add optional ACK filter

From: Toke Høiland-Jørgensen <[email-masked]>
Date: Thu, 17 May 2018 15:11:31 +0200

Eric Dumazet <[email-masked]> writes:

> On 05/17/2018 04:23 AM, Toke Høiland-Jørgensen wrote:
>
>> 
>> We don't do full parsing of SACKs, no; we were trying to keep things
>> simple... We do detect the presence of SACK options, though, and the
>> presence of SACK options on an ACK will make previous ACKs be considered
>> redundant.
>> 
>
> But they are not redundant in some cases, particularly when reorders
> happen in the network.

Huh. I was under the impression that SACKs were basically cumulative
until cleared.

I.e., in packet sequence ABCDE where B and D are lost, C would have
SACK(B) and E would have SACK(B,D). Are you saying that E would only
have SACK(D)?

-Toke