From: Carlos Alberto Trujillo Jimenez (carlos.trujillo.jimenez@gmail.com)
Date: Mon Mar 03 2008 - 18:20:21 ARST
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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