That brings up an interesing point.
My biggest fear was that one of my other customers could possible
be closer to me that the ISP that provides the primary link and it would
cause them to favor the backup link because of AS path. I think they
are going to fight me on this and telling them to multihome to their original
ISP would probably be frowned upon at this point. I was hoping that
there was an RFC for multihoming that I could use to bail myself out.
"Justin M. Streiner"
<streiner@cluebyfour.org> Sent by: owner-nanog@merit.edu
10/08/2007 05:55 PM
To
Keegan.Holley@sungard.com
cc
nanog <nanog@merit.edu>
Subject
Re: How Not to Multihome
On Mon, 8 Oct 2007, Keegan.Holley@sungard.com wrote:
> I have a client that wants us to advertise an IP block assigned by
another
> ISP. I know that the best practice is to have them request an
AS number
> from ARIN and peer with us, etc. However, I cannot find any
information
> that states as law. Does anyone know of a document or RFC that
states
> this?
It's not 'law' per se, but having the customer originate their own
announcements is definitely the Right Way to go.
Some providers take a pretty dim view of seeing chunks of their address
space show up in advertisements originating from someone who isn't one
of
their customers. It can make troubleshooting connectivity problems
for
that customer (from the provider's point of view) very painful, i.e. "Hey,
this AS, who isn't one of our customers, is hijacking IP space assigned
to
one of our customers!" The provider could then contact your
host's
upstream(s) and ask them to drop said announcement under the impression
they're stopping someone from doing something bad.
Also, if some network out there aggregates prefixes in an aggessive/odd
manner, the disjoint announcement, and the reachability info it contains
could be washed out of their routing tables, causing connectivity
problems.
Standard caveats about the block being a /24 or larger also apply.