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To: "Rodney W. Grimes" <4bone@gndrsh.dnsmgr.net>
Cc: "Rodney W. Grimes" <4bone@gndrsh.dnsmgr.net>,
 Luca Muscariello <muscariello@ieee.org>, Rich Brown <richb.hanover@gmail.com>,
 ECN-Sane <ecn-sane@lists.bufferbloat.net>
In-Reply-To: <201911131525.xADFPQ61044389@gndrsh.dnsmgr.net>
References: <201911131525.xADFPQ61044389@gndrsh.dnsmgr.net>
Date: Wed, 13 Nov 2019 16:35:15 +0100
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Subject: Re: [Ecn-sane] Meanwhile, over on NANOG...
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"Rodney W. Grimes" <4bone@gndrsh.dnsmgr.net> writes:

>> -t is the TOS value; so those two happen to correspond to ECT(1) and
>> ECT(0); and as you can see they go two different paths. Which would be
>> consistent with the SYN going one way and the data packets going
>> another.
>
> Perhaps Old enough that maybe they are treating that as TOS byte?
>
> Looks like you have nailed it though, someone has a broken hash.

Yup, seems like it. Posted a writeup to the NANOG list in response to
the guy asking; it hasn't showed up in the archive, though, so I guess
it's still in the moderation queue.

I think I'll write the whole thing up as a blog post as well, once it's
resolved. I'll see if I can get them to tell me which router make and
model is doing this.

Thanks everyone who helped with ideas etc! :)

-Toke