Subject: [GROW] Re: A well-known DOWNGRADE BGP Community
From: Bryton Herdes <[email-masked]>
To: Job Snijders <job=[email-masked]>
Cc: [email-masked], [email-masked]
Date: Wed, 5 Aug 2026 18:05:40 +0100
List-Id: Grow Working Group Mailing List <grow.ietf.org>

Hey folks -

Is the second instance of "BLACKHOLE" meant to be "DOWNGRADE" here in
section 3.4?

"Similar to how IX RS ought to pass through the BLACKHOLE community (see
Section 3.3), the global Internet routing system as a whole likely benefits
from downgrading close to the traffic source. Operators SHOULD NOT remove
the BLACKHOLE community from route announcements."

--
Bryton Herdes
Principal Network Engineer
AS13335 - Cloudflare

On Tue, Aug 4, 2026 at 2:44 PM Job Snijders <job=[email-masked]>
wrote:

> Dear all,
>
> Following up on a recent NANOG thread on RTBH [1], [2]; we'd like to put
> forward an different strategy for DoS attack mitigation. Perhaps just as
> an extra tool in the toolbox?
>
>    Abstract --
>    This document outlines a method to mitigate Denial of Service (DoS)
>    attacks by using a well-known BGP community named "DOWNGRADE" as signal
>    to neighboring networks to treat traffic destined towards "DOWNGRADE"
>    tagged IP prefixes with low precedence. The "downgrade" strategy
>    offers an appealing alternative to Remote Triggered Blackhole (RTBH)
>    filtering, because RTBH filtering completes the DoS attack and hampers
>    the defender's ability to monitor whether the attack is still ongoing.
>
> Please read the full draft document here:
>
>
> https://datatracker.ietf.org/doc/html/draft-spaghetti-grow-downgrade-bgp-community
>
> Your feedback is most welcome!
>
> Kind regards,
>
> Job
>
> [1]:
> https://lists.nanog.org/archives/list/[email-masked]/message/LOWUU7RHOKTYKVGWRHNXQJ3GSJYN3HLE/
> [2]:
> https://lists.nanog.org/archives/list/[email-masked]/message/ITDOCC6N5VELZ56F6ILVZODZSUWH3TNE/
>
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