nanog mailing list archives

Re: Prepending with another ASN you don't own


From: Rubens Kuhl <rubensk () gmail com>
Date: Fri, 16 Dec 2016 08:13:50 -0200

Even in that case I believe you should encapsulate between two instances of
your own ASN. Your example follows this but the text says only about the
last one in the path, while having both last and at least one previous is
better since you won't be implying that some other AS has connection to yet
another AS, it's just you doing this.

Rubens


On Thu, Dec 15, 2016 at 4:54 PM, Andrew Imeson <andrew () andrewimeson com>
wrote:

Is it acceptable to prepend using another networks ASN as long as your
ASN is the last one in the path? I can think of a few scenarios where
this is helpful.

One scenario: Anycast content provider with an ISP (who you aren't
directly peering with) is choosing to send all traffic to a PoP on
another
continent.

Solution:
Prepend at the geographically-distant PoP so that the AS path looks
like <ACME> <BAD-ISP> <ACME>, and thus that service provider
(<BAD-ISP>)
views it as a routing loop and chooses one of your other PoPs. Sure
there are better solutions like communities, but why (if it is) would
this
be "bad?"

--
Andrew Imeson
andrew () andrewimeson com



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