RE: how about a well-known DOWNGRADE BGP Community? (Was: RTBH Support Across the Industry)

+1.  Was going to follow up to Saku's message about how/if folks are doing that in JunOS [or other OS] natively without outside automation.   Our backbone has scavenger style plp in BE, I control admission via prefix-list in ingress fwfilter on untrusted interfaces.  Haven't personally tested but looks like DCU + forwarding-table export policy + output firewall filter, maybe this is possible today but requires output fwfilter to family mpls.  I don't currently have a fwfilter there so ideally another option exists.

-Michael

> -----Original Message-----
> From: jim deleskie via NANOG <[email protected]>
> Sent: Tuesday, August 4, 2026 9:00 AM
> To: North American Network Operators Group <[email protected]>
> Cc: jim deleskie <[email protected]>
> Subject: Re: how about a well-known DOWNGRADE BGP Community? (Was:
> RTBH Support Across the Industry)
> 
> I fully support this direction.
> 
> Job, anything I can do to assist, let me know please
> 
> -jim
> 
> On Tue, Aug 4, 2026 at 9:38 AM Job Snijders via NANOG
> <[email protected]>
> wrote:
> 
> > Dear all,
> >
> > Following up on the RTBH thread, 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.
> >
> > Read the full draft document here:
> >
> >
> > https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/draft-
> spaghetti-grow-downgrade-bgp-
> community__;!!Mak6IKo!I84uSQpoZr3Hgeb0DCb0OohZiOXtp1cZcaeVckp1CLt4n
> T_niCJvjcUFGnTGsreTP8yeCSencjX90coak9bz$
> >
> > Your feedback is most welcome!
> >
> > Kind regards,
> >
> > Job
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