The initial and recurring packet loss occurs on any flow of more than ~140 Mbit.  The fact that it’s loss-free under that rate is what furthers my opinion it’s config-based somewhere, even though they say it isn’t.

From: NANOG <nanog-bounces+dhubbard=dino.hostasaurus.com@nanog.org> on behalf of Mark Tinka <mark@tinka.africa>
Date: Friday, September 1, 2023 at 10:13 AM
To: Mike Hammett <nanog@ics-il.net>, Saku Ytti <saku@ytti.fi>
Cc: nanog@nanog.org <nanog@nanog.org>
Subject: Re: Lossy cogent p2p experiences?

On 9/1/23 15:44, Mike Hammett wrote:

and I would say the OP wasn't even about elephant flows, just about a network that can't deliver anything acceptable.

Unless Cogent are not trying to accept (and by extension, may not be able to guarantee) large Ethernet flows because they can't balance them across their various core links, end-to-end...

Pure conjecture...

Mark.