From: Hash Aminu (hashng@gmail.com)
Date: Tue Mar 04 2008 - 08:48:42 ARST
Hi,
your situation will not be clearly understood without the
topology...i would figure out that u have mutual redistribution in
more than one point ...in that sense i would have to play with the AD
not to have the redistributed routes from one end gets back and cause
routing loop......just a general view though
HTH
Hash
On 3/4/08, John <jgarrison1@austin.rr.com> wrote:
> As I said the rip is a stub network. Now when rip is applying a default AD
> of 109 to all redistributed routes it means that the ospf routes that have
> been redistributed into rip will have a lower AD than the original ospf
> routes on the ABSR. For all intents and purposes I am disregarding any
> issues with rip beig redistributed into ospf at this point. I'm trying to
> see the logic of making the AD of the redistributed routes lower than that
> of the originating routing protocol
>
> I do get the fact that different topologies will require different methods.
> I'm trying to understand the logic this specific "tool"
> ----- Original Message -----
> From: "Carlos Alberto Trujillo Jimenez" <carlos.trujillo.jimenez@gmail.com>
> To: "John" <jgarrison1@austin.rr.com>
> Cc: <ccielab@groupstudy.com>
> Sent: Monday, March 03, 2008 2:20 PM
> Subject: Re: redistribution
>
>
> > as you mention "On a couple of occasions" but not in all, why not in all??
> > because every topology is different.
> > Im trying to figure your topology scenario and what I understand is you
> > have
> > one rip domain considered STUB (only one exit point). One router is
> > redistributing rip into ospf.
> > The decision of changing the administrative distance in rip depends
> > specifically in the ospf topology.
> > For example, if you follow the path of a native rip route redistributed
> > into
> > ospf and then that same "initially rip native route" come back to the
> > router
> > doing the redistribution but from another ospf router there is a
> > possibility
> > you HAVE A routing loop, because you know that the TRUE PATH towards the
> > native rip route is following the rip domain, not the OSPf domain, but if
> > the router doing the redistribution recibes the same prefix by two rouring
> > protocols (RIP AND OSPF) it prefers the ospf one, because of its
> > administrative distance.
> >
> > Again, this could happen depending in the physical topology, I assume in
> > your phisical topology diagram the OSPF ASBR ROUTER has two paths towards
> > the OSPF DOMAIN, and it makes sense, because if it sends and advertisement
> > to one path it could recibe that same advertisement from another path
> > (sourced from another neighbor), and it could belive it has a better path
> > to
> > the rip prefix than the rip path. as a conclusion the LOOP is formed.
> >
> > So to prevent that looping you must decrease the A.D in rip in the router
> > doing redistribution
> >
> > It is better to understand looking at the diagram, following the path of
> > the
> > redistributed routes.
> > remeber, there are some topologies where a redistributed route maybe come
> > back to the router doing redistribution via different path. In that
> > scenarios, and depending the routing protocols, you may need to change the
> > A.D. to prevent a loop.
> >
> >
> >
> > You are redistributing rip into ospf,
> >
> > 2008/3/3, John <jgarrison1@austin.rr.com>:
> >>
> >> I seem to have started to get a handle on route redistribution. Theres
> >> one
> >> thing I keep seeing that I can't make sense of. is a router
> >> redistributing
> >> ospf and ripv2. On a couple of occasions I've seen ospf redistributed
> >> into
> >> rip with a distance of 109. This means that rip routes will have a lower
> >> AD
> >> thasn the OSPF routes. Therip network is a stub. what am I missing. I
> >> kind
> >> of get tags, route-maps and the the AD on external routes, bhut I don't
> >> get
> >> this.
> >>
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