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From: Bryton Herdes <bryton@cloudflare.com>
Date: Wed, 5 Aug 2026 18:05:40 +0100
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 <CADXn3HTLZMxRiPg=i8DbCzgi5_GSej9F1HEo06x44p=u0MawUw@mail.gmail.com>
To: Job Snijders <job=40bsd.nl@dmarc.ietf.org>
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Subject: =?utf-8?q?=5BGROW=5D_Re=3A_A_well-known_DOWNGRADE_BGP_Community?=
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 <https://mailarchive.ietf.org/arch/msg/grow/TN77xAz5UmWeVuBvTyBYglbxGeg>

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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=E2=80=AFPM Job Snijders <job=3D40bsd.nl@dmarc.i=
etf.org>
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 signa=
l
>    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/nanog@lists.nanog.org/message/LOWUU=
7RHOKTYKVGWRHNXQJ3GSJYN3HLE/
> [2]:
> https://lists.nanog.org/archives/list/nanog@lists.nanog.org/message/ITDOC=
C6N5VELZ56F6ILVZODZSUWH3TNE/
>
> _______________________________________________
> GROW mailing list -- grow@ietf.org
> To unsubscribe send an email to grow-leave@ietf.org
>

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<div dir=3D"ltr"><div>Hey folks -=C2=A0<br><br>Is the second instance of &q=
uot;BLACKHOLE&quot; meant to be &quot;DOWNGRADE&quot; here in section 3.4?=
=C2=A0<br><br>&quot;<span style=3D"background-color:transparent">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 downgra=
ding close to the traffic source. Operators SHOULD NOT remove the BLACKHOLE=
 community from route announcements.&quot;<br><br><br></span></div><div><di=
v dir=3D"ltr" class=3D"gmail_signature" data-smartmail=3D"gmail_signature">=
<div dir=3D"ltr"><div style=3D"color:rgb(136,136,136)">--</div><div style=
=3D"color:rgb(136,136,136)">Bryton Herdes</div><div style=3D"color:rgb(136,=
136,136)">Principal Network Engineer</div><div style=3D"color:rgb(136,136,1=
36)">AS13335 - Cloudflare</div></div></div></div><br></div><br><div class=
=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr=
">On Tue, Aug 4, 2026 at 2:44=E2=80=AFPM Job Snijders &lt;job=3D<a href=3D"=
mailto:40bsd.nl@dmarc.ietf.org">40bsd.nl@dmarc.ietf.org</a>&gt; wrote:<br><=
/div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bo=
rder-left:1px solid rgb(204,204,204);padding-left:1ex">Dear all,<br>
<br>
Following up on a recent NANOG thread on RTBH [1], [2]; we&#39;d like to pu=
t<br>
forward an different strategy for DoS attack mitigation. Perhaps just as<br=
>
an extra tool in the toolbox?<br>
<br>
=C2=A0 =C2=A0Abstract --<br>
=C2=A0 =C2=A0This document outlines a method to mitigate Denial of Service =
(DoS)<br>
=C2=A0 =C2=A0attacks by using a well-known BGP community named &quot;DOWNGR=
ADE&quot; as signal<br>
=C2=A0 =C2=A0to neighboring networks to treat traffic destined towards &quo=
t;DOWNGRADE&quot;<br>
=C2=A0 =C2=A0tagged IP prefixes with low precedence. The &quot;downgrade&qu=
ot; strategy<br>
=C2=A0 =C2=A0offers an appealing alternative to Remote Triggered Blackhole =
(RTBH)<br>
=C2=A0 =C2=A0filtering, because RTBH filtering completes the DoS attack and=
 hampers<br>
=C2=A0 =C2=A0the defender&#39;s ability to monitor whether the attack is st=
ill ongoing.<br>
<br>
Please read the full draft document here:<br>
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 <a href=3D"https://datatracker.ietf.org/doc/htm=
l/draft-spaghetti-grow-downgrade-bgp-community" rel=3D"noreferrer" target=
=3D"_blank">https://datatracker.ietf.org/doc/html/draft-spaghetti-grow-down=
grade-bgp-community</a><br>
<br>
Your feedback is most welcome!<br>
<br>
Kind regards,<br>
<br>
Job<br>
<br>
[1]: <a href=3D"https://lists.nanog.org/archives/list/nanog@lists.nanog.org=
/message/LOWUU7RHOKTYKVGWRHNXQJ3GSJYN3HLE/" rel=3D"noreferrer" target=3D"_b=
lank">https://lists.nanog.org/archives/list/nanog@lists.nanog.org/message/L=
OWUU7RHOKTYKVGWRHNXQJ3GSJYN3HLE/</a><br>
[2]: <a href=3D"https://lists.nanog.org/archives/list/nanog@lists.nanog.org=
/message/ITDOCC6N5VELZ56F6ILVZODZSUWH3TNE/" rel=3D"noreferrer" target=3D"_b=
lank">https://lists.nanog.org/archives/list/nanog@lists.nanog.org/message/I=
TDOCC6N5VELZ56F6ILVZODZSUWH3TNE/</a><br>
<br>
_______________________________________________<br>
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et=3D"_blank">grow-leave@ietf.org</a><br>
</blockquote></div>

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