DSACK

[Michael Tuexen]

> On 24. Feb 2019, at 12:32, Randall Stewart <rrs at netflix.com> wrote:
> 
> I don’t think I have ever seen FreeBSD emit a DSACK. Now admittedly
> I have only paid close attention in current. But that spans even back
> into 11 days I think.
> 
> Hmm wonder if I have a 10 machine I can go back and look at :)
I tried to test on 10.4 yesterday, but packetdrill doesn't run that
well on 10.4 (missing pcap functions)... I'm not sure I want to backport it.

Best regards
Michael
> 
> R
> 
>> On Feb 23, 2019, at 5:30 AM, Michael Tuexen <tuexen at freebsd.org> wrote:
>> 
>>> On 23. Feb 2019, at 11:28, Scheffenegger, Richard <Richard.Scheffenegger at netapp.com> wrote:
>>> 
>>> 
>>> Bin grad am flughafen und hab leider nur HEAD bei mir (und ein iso von 10, wo ich grad versuch, das mit scapy zu checken).
>>> 
>>> Falls du schnell einen packetdrill gegen BSD11 ohne D18960 machen kannst, und es da noch DSACKs raussendet, wäre das toll!
>>> 
>>> Ich fürchte aber, das das schon längere Zeit kaputt ist - da wir nun doch noch nicht D18960 drinnen haben, wie ich irrtümlich dachte.
>> OK. I'll take a look.
>> 
>> Have a save trip!
>> 
>> Best regards
>> Michael
>>> 
>>> 
>>> 
>>> -----Original Message-----
>>> From: Michael Tuexen <tuexen at freebsd.org> 
>>> Sent: Samstag, 23. Februar 2019 11:25
>>> To: Scheffenegger, Richard <Richard.Scheffenegger at netapp.com>
>>> Cc: freebsd-transport at freebsd.org
>>> Subject: Re: DSACK
>>> 
>>> NetApp Security WARNING: This is an external email. Do not click links or open attachments unless you recognize the sender and know the content is safe.
>>> 
>>> 
>>> 
>>> 
>>>> On 23. Feb 2019, at 10:29, Scheffenegger, Richard <Richard.Scheffenegger at netapp.com> wrote:
>>>> 
>>>> Hi,
>>>> 
>>>> A colleague pointed me to the stack (HEAD) no longer emitting DSACK options a few days ago...
>>>> 
>>>> I was under the impression, that older versions of FreeBSD would send out DSACKs for spurious duplicate packets.
>>>> 
>>>> But when I try this script against HEAD, regular cumulative ACKs without DSACK blocks are showing up.
>>>> 
>>>> Currently bandwidth starved - but was that a conscious decision? Or was me observing DSACKs never a thing?
>>> I would say if it is working in stable/11, but not in stable/12 and head, it is a regression.
>>> 
>>> Best regards
>>> Michael
>>>> 
>>>> Thanks a lot,
>>>> Richard
>>>> 
>>> 
>> 
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> 
> ------
> Randall Stewart
> rrs at netflix.com
> 
> 
>