[99892] in North American Network Operators' Group
Re: How Not to Multihome
daemon@ATHENA.MIT.EDU (Keegan.Holley@sungard.com)
Mon Oct 8 18:22:42 2007
In-Reply-To: <Pine.LNX.4.64.0710081744060.4258@whammy.cluebyfour.org>
To: "Justin M. Streiner" <streiner@cluebyfour.org>
Cc: nanog <nanog@merit.edu>, owner-nanog@merit.edu
From: Keegan.Holley@sungard.com
Date: Mon, 8 Oct 2007 18:14:51 -0400
Errors-To: owner-nanog@merit.edu
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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.
jms
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<br><font size=2 face="sans-serif">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.</font>
<br>
<br>
<br>
<br>
<br>
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<td width=40%><font size=1 face="sans-serif"><b>"Justin M. Streiner"
<streiner@cluebyfour.org></b> </font>
<br><font size=1 face="sans-serif">Sent by: owner-nanog@merit.edu</font>
<p><font size=1 face="sans-serif">10/08/2007 05:55 PM</font>
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<div align=right><font size=1 face="sans-serif">To</font></div>
<td><font size=1 face="sans-serif">Keegan.Holley@sungard.com</font>
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<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td><font size=1 face="sans-serif">nanog <nanog@merit.edu></font>
<tr valign=top>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">Re: How Not to Multihome</font></table>
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<tr valign=top>
<td>
<td></table>
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<br><tt><font size=2><br>
On Mon, 8 Oct 2007, Keegan.Holley@sungard.com wrote:<br>
<br>
> I have a client that wants us to advertise an IP block assigned by
another<br>
> ISP. I know that the best practice is to have them request an
AS number<br>
> from ARIN and peer with us, etc. However, I cannot find any
information<br>
> that states as law. Does anyone know of a document or RFC that
states<br>
> this?<br>
<br>
It's not 'law' per se, but having the customer originate their own <br>
announcements is definitely the Right Way to go.<br>
<br>
Some providers take a pretty dim view of seeing chunks of their address
<br>
space show up in advertisements originating from someone who isn't one
of <br>
their customers. It can make troubleshooting connectivity problems
for <br>
that customer (from the provider's point of view) very painful, i.e. "Hey,
<br>
this AS, who isn't one of our customers, is hijacking IP space assigned
to <br>
one of our customers!" The provider could then contact your
host's <br>
upstream(s) and ask them to drop said announcement under the impression
<br>
they're stopping someone from doing something bad.<br>
<br>
Also, if some network out there aggregates prefixes in an aggessive/odd
<br>
manner, the disjoint announcement, and the reachability info it contains
<br>
could be washed out of their routing tables, causing connectivity <br>
problems.<br>
<br>
Standard caveats about the block being a /24 or larger also apply.<br>
<br>
jms<br>
<br>
<br>
</font></tt>
<br>
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