From: John (jgarrison1@austin.rr.com)
Date: Tue Mar 04 2008 - 00:25:46 ARST
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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