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<p>One more thing, RFC7999 has category Informational<br>
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<div class="moz-cite-prefix">El 31/1/19 a las 16:21, Theodore
Baschak escribió:<br>
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<div class="">On Jan 31, 2019, at 1:28 PM, Roel Parijs <<a
href="mailto:roel.parijs@gmail.com" class=""
moz-do-not-send="true">roel.parijs@gmail.com</a>>
wrote:</div>
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<div class="">For our BGP customers the problem is more
complex. Our BGP customers can send us the RTBH
community, and we will drop the traffic at our
borders. Since we're only running a small network, we
don't have the capacity to deal with large attacks. If
we would be able to forward (and maybe alter it) this
RTBH community towards our upstream providers, the
impact on our network would be limited. However, the
RFC states that an announcement tagged with the
blackhole community should get the no_advertise or
no_export community.</div>
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<div class="">What is your opinion on this ?</div>
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<div class="">In RFC7999 section 3.2 the first paragraph talks
about what you're mentioning, NO_EXPORT and/or NO_ADVERTISE. It
uses the word SHOULD. SHOULD has special meaning in RFCs, its
not MUST. Its also not MAY. RFC2119 talks about the way these
words should be interpreted. </div>
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<div class="">In the next paragraph it says that extreme caution
should be used when "purposefully propagating IP prefixes tagged
with the BLACKHOLE community outside the local routing domain,
unless policy explicitly aims at doing just that."</div>
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<div class="">So if your local routing policy is to propagate
those blackholes on to your upstreams (and its mutually agreed
and they're configured to accept them), then it can be done.
Nothing technical in the RFC stopping that. </div>
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<div class="">Theo</div>
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