Re: set as-path prepend

From: George Robbins (grr@shandakor.tharsis.com)
Date: Mon Apr 23 2001 - 16:51:51 EDT


The most important thing to remember is to set attributes only at the
origin/entry point of the route, or if you really, really need to
change them as they pass thru your network, do it in such a way that
routes only get *worse*, not better. Otherwise you'll always be having
problems with routing loops.

as-path and metrics provide "safe" ways to incrementally downgrade
routes, with local-pref you can set values and then "set to zero"
if you want to discourage use of a route from some point.

                                                        George

> From cisco-nsp-request@puck.nether.net Mon Apr 23 16:39:41 2001
> Resent-Date: Mon, 23 Apr 2001 16:39:24 -0400
> Received-Date: Mon, 23 Apr 2001 16:37:01 -0400
> Date: Mon, 23 Apr 2001 22:37:25 +0200
> From: Gert Doering <gert@greenie.muc.de>
> To: Christian Kratzer <ck@toplink.net>, Scott Whyte <swhyte@cisco.com>
> Cc: Marc Williams <mw@uk.yahoo-inc.com>, cisco-nsp@puck.nether.net
> Subject: Re: set as-path prepend
> References: <Pine.WNT.4.33.0104231127190.1064-100000@wwhyte-w2k.cisco.com> <Pine.LNX.4.21.0104232052410.1050-100000@hirvi.toplink.net>
> In-Reply-To: <Pine.LNX.4.21.0104232052410.1050-100000@hirvi.toplink.net>; from Christian Kratzer on Mon, Apr 23, 2001 at 08:53:50PM +0200
> X-mgetty-docs: http://alpha.greenie.net/mgetty/
> Resent-From: cisco-nsp@puck.nether.net
> X-Mailing-List: <cisco-nsp@puck.nether.net> archive/latest/6152
> X-Loop: cisco-nsp@puck.nether.net
> Precedence: list
> Resent-Sender: cisco-nsp-request@puck.nether.net
>
> Hi,
>
> On Mon, Apr 23, 2001 at 08:53:50PM +0200, Christian Kratzer wrote:
> > nevertheless as-path prending does also work inside an as with ibgp sessions.
> > Local preference is a far better way to go with ibgp peers though.
>
> Depends. *Increasing* local-pref on iBGP-Peerings can lead to pretty
> non-deterministic routing. Decreasing is OK.
>
> I prefer MED, though, as there are less ways to shoot yourself with that.
>
> gert
> --
> USENET is *not* the non-clickable part of WWW!
> //www.muc.de/~gert/
> Gert Doering - Munich, Germany gert@greenie.muc.de
> fax: +49-89-35655025 gert.doering@physik.tu-muenchen.de
>
>



This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:12:35 EDT