AS701 peer local-pref?

Mike Leber mleber at he.net
Sun Dec 16 09:07:39 UTC 2001


If they set local pref for both peers and customers to 100 how do they
ensure that the customer transit routes are announced to peers?

The reason I ask this is because if a customer announces a customer of
theirs to you that a peer also has as a customer you will have equal
length routes for the same destination AS.  While there are many ways to
deterministicly prefer customer routes, local pref is the most common.

Your core routers will only propagate the best route in their routing
tables (normally).

Assuming you have more than one BGP speaking router in your network, if
you don't deterministicly prefer your customer routes (including their
downstreams) then you won't deterministicly announce them for your
customer.  Most commonly when somebody pays for transit they want you to
advertise their routes (including any customer routes they announce to
you) to the world.

Mike.

On Fri, 14 Dec 2001, Me wrote:

> 
> All the responses I have gotten indicate that UUnet does indeed set
> local-pref on both customers and peers to 100 (or leave default in this
> case).  Thanks for all the responses...
> 
> 
> -- 
> -sean
> Spoon!
> 
> On Fri, 14 Dec 2001, Christopher A. Woodfield wrote:
> 
> > Date: Fri, 14 Dec 2001 12:01:39 -0500
> > From: Christopher A. Woodfield <rekoil at semihuman.com>
> > To: German Martinez <gmartine at nic.gip.net>
> > Cc: Me <smentzer at mentzer.org>, nanog at merit.edu
> > Subject: Re: AS701 peer local-pref?
> >
> > I think you misunderstood the question - what you have detailed here is a
> > list of customer communities that UUNet accepts, what Sean is trying to
> > find out is what internal localpref UUNet sets by default - do they
> > automatically give prefixes from customers a higher localpref than
> > prefixes heard from peers? I don't know for sure, but I'm thinking that
> > they do, which makes sense - otherwise it's possible to send traffic to a
> > peer when there could be a valid path for the traffic via a customer.
> >
> > -Chris
> >
> > On Wed, Dec 12, 2001 at 04:14:26PM -0500, German Martinez wrote:
> > >
> > > SHORT NAME              COMMUNITY       WHAT IT DOES
> > > Local Pref = 80         701:80          set localpref 80
> > > Local Pref = 120        701:120         set localpref 120
> > > AS Path prepend 1       701:1           prepend 1x: 701 [cust-AS]
> > > AS Path prepend 2       701:2           prepend 2x: 701 701 [cust-AS]
> > > AS Path prepend 3       701:3           prepend 3x: 701 701 701 [cust-AS]
> > > Cust but not peers      701:20          propagate to custs, not peers
> > > keep cust routes in North America       701:30  send to custs & peers, but
> > > not 702, 703...
> > > keep AS7046 in AS701    no-export       don't propagate beyond AS701
> > > peers                   701:666         don't propagate beyond this AS
> > > peers                   701:1030        don't propagate beyond this AS
> > >
> > >
> > >
> > >
> > >
> > >
> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > * THE DILBERT FUTURE *
> > > * Thriving on Stupidity in the 21st Century *
> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > "Internet capacity will increase indefinitely
> > > to keep up with the egos of the people using it"
> > >
> > > On Wed, 12 Dec 2001, Me wrote:
> > >
> > > >
> > > >
> > > > Does anyone know what local-pref AS701 sets for their customers and their
> > > > peers?  I called their NOC, and was told that is was set to 100 for both,
> > > > though I know most providers set local-pref on peers lower than customers.
> > > > I just want to get confirmation on what i was told by their NOC.
> > > >
> > > > TIA.
> > > >
> > > > --
> > > > -sean
> > > > Spoon!
> > > >
> > > >
> > >
> >
> >
> 

+------------------- H U R R I C A N E - E L E C T R I C -------------------+
| Mike Leber             Direct Internet Connections     Voice 510 580 4100 |
| Hurricane Electric       Web Hosting  Colocation         Fax 510 580 4151 |
| mleber at he.net                                           http://www.he.net |
+---------------------------------------------------------------------------+




More information about the NANOG mailing list