RE: [nsp] how to fool the SPF in OSPF?

From: George Robbins (grr@shandakor.tharsis.com)
Date: Mon Jun 11 2001 - 18:31:13 EDT


The KISS solution is that everything is area 0 until such time
has you *need* to restrict routes in/out of a section of your
network. Typically those areas will have defined interfaces to
the backbone, segemented your network "because you can" usually
leads to problems you never needed to encounter. 8-)

                                                George

> From cisco-nsp-request@puck.nether.net Mon Jun 11 17:21:50 2001
> Resent-Date: Mon, 11 Jun 2001 17:21:36 -0400
> Received-Date: Mon, 11 Jun 2001 17:19:16 -0400
> From: "Martin, Christian" <cmartin@gnilink.net>
> To: "'Chris Davis'" <chris.davis@computerjobs.com>,
> "'jlewis@lewis.org'"
> <jlewis@lewis.org>, cisco-nsp@puck.nether.net
> Subject: RE: [nsp] how to fool the SPF in OSPF?
> Date: Mon, 11 Jun 2001 17:19:02 -0400
> Resent-From: cisco-nsp@puck.nether.net
> X-Mailing-List: <cisco-nsp@puck.nether.net> archive/latest/6768
> X-Loop: cisco-nsp@puck.nether.net
> Precedence: list
> Resent-Sender: cisco-nsp-request@puck.nether.net
>
> Cisco is supposed to be developing a knob to make OSPF look at cost only.
> IS-IS has had success with this idea recently.
>
> chris
>
> > -----Original Message-----
> > From: Chris Davis [mailto:chris.davis@computerjobs.com]
> > Sent: Monday, June 11, 2001 4:05 PM
> > To: 'jlewis@lewis.org'; cisco-nsp@puck.nether.net
> > Subject: RE: [nsp] how to fool the SPF in OSPF?
> >
> >
> > The order of preference for OSPF routes are as follows:
> >
> > intra-area routes, O
> > inter-area routes O IA
> > external routes type 1, O E1
> > external routes type 2, O E2
> >
> > I'm not completely sure about your areas, but it looks like
> > you want traffic
> > from routerB to traverse area1 to routerA in area 0.
> >
> > If the T1s could be in area 1 rather than area 0, as they
> > probably should be
> > based on bandwidth, your problem should be solved.
> >
> >
> >
> > -----Original Message-----
> > From: jlewis@lewis.org [mailto:jlewis@lewis.org]
> > Sent: Monday, June 11, 2001 3:46 PM
> > To: cisco-nsp@puck.nether.net
> > Subject: [nsp] how to fool the SPF in OSPF?
> >
> >
> > Given a network such as:
> >
> > -----------------------------------
> > | routerA------T3------routerC |
> > |___ | _________________ | __| area 0
> > | | | | | |
> > | T1s | | T3 |
> > | | / | | |
> > \ | / /-------------\ \ | /
> > routerB-----100bt------routerD
> > \-------------/
> > area 1
> >
> > how do I get around the T1's connecting A and B being the
> > shortest path
> > and get B to send traffic to A via D unless one of the T3's
> > above is down?
> > I can't just use static routes on B, because it won't know if a T3 is
> > down. I've tried playing with "ip ospf cost" on the T1's but B still
> > prefers them.
> >
> > --
> > ----------------------------------------------------------------------
> > Jon Lewis *jlewis@lewis.org*| I route
> > System Administrator | therefore you are
> > Atlantic Net |
> > _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
> >
>
>



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