[89809] in North American Network Operators' Group
Re: IP ranges, re- announcing 'PA space' via BGP, etc
daemon@ATHENA.MIT.EDU (Stephen Sprunk)
Fri Apr 7 12:56:28 2006
From: "Stephen Sprunk" <stephen@sprunk.org>
To: "Alexander Koch" <efraim@clues.de>,
"Patrick W. Gilmore" <patrick@ianai.net>
Cc: "North American Noise and Off-topic Gripes" <nanog@merit.edu>
Date: Fri, 7 Apr 2006 11:55:41 -0500
Errors-To: owner-nanog@merit.edu
Thus spake "Alexander Koch" <efraim@clues.de>
> On Fri, 7 April 2006 07:03:09 -0400, Patrick W. Gilmore wrote:
>> Can you give us some examples so us "dumb Americans" can more
>> precisely explain the problem? :)
>
> When a random customer (content hoster) asks you to accept
> something out of 8/8 that is Level(3) space, and there is no
> route at this moment in the routing table, do you accept it,
> or does Level(3) have some fancy written formal process and
> they get approval to do it, etc.?
>
> In Europe we would tell the customer this ain't gonna happen,
> as we would re- announce blocks out of 'foreign' LIR allocations
> and that is a no-go, unless the holder of that allocations
> acks that.
Here, it seems that some ISPs will accept foreign PA routes* _as long as the
customer is still connected to that other provider_. Some won't under any
circumstances. The remainder aren't filtering their downstreams and have no
clue what they are providing transit for (i.e. it's the customer's job to
get it right).
If you do decide to accept a foreign PA route, you need to be very careful
to point out to the customer (a) some people will filter your route for
being too long and send their traffic to the owning provider, and (b) if the
other provider doesn't announce the longer prefix in addition to their
aggregate, anyone who accepts the longer route will send traffic only to you
due to longest match. Both cases can result in suboptimal routing.
The correct** solution is to help them become an LIR, assuming they qualify.
S
* meaning a route for part of another ISP's aggregate
** for some values of "correct"
Stephen Sprunk "Stupid people surround themselves with smart
CCIE #3723 people. Smart people surround themselves with
K5SSS smart people who disagree with them." --Aaron Sorkin
