From: Jongsoo (bstrt2004@gmail.com)
Date: Sun Nov 06 2005 - 01:48:34 GMT-3
tagging would be my choice as well.
In general, EIGRP is a real troublemaker when you have EIGRP external
routes to be redistributed to OSPF...I am sure you know what I mean.
In a CCEI lab, when it comes to mutual route distribution via
multi-exit points,
as a rule of thumb, core and stub IGP protocols need to determined.
From stub to core, core protocol only accepts stub routes .
From core to stub, stub protocol denies the reentry of its own routes
from core and accept all other routes. Of course, this method will
require route-map and ACL...
But if stub or core protocol is EIRP, it get more complicated because
EIGRP uses two different AD for internal and external. For example,
if EIGRP redistributes a "already redistributed routes" ( for exmaple,
redistribute connected or eigrp external routes ) to OSPF, and EIGRP
and OSPF run on two routers so multi-exit points...this would be one
of the most complicated redistribution scenario but it will really
help to understand the bahavior of multi-protocol-running router.
Defining internal routes of each routing protocol really helps in many cases.
Sometimes, it is hard to see a routing loop because it converge every
miniute or two. Depending the time you look into routing table, you
never catch that...
Jongsoo
On 11/5/05, Schulz, Dave <DSchulz@dpsciences.com> wrote:
> This is a great subject, and one that I have been wrestling with for awhile.
> I have used the ACLs for the distribution, but Kevin is right...you have to
> maintain the ACLs. And, in a dynamic environment, this may take a lot more
> admin than one would care to admit. I have found that easiest way to do the
> redistribution is by using tags. I try to keep the same tag number as the
> administrative distance to keep things straight. So, if I am redistributing
> from OSPF to EIGRP....I use 110 as the tag and 90 in the reverse direction.
> This seems to work well and is very easy to implement and keep things
> straight.
>
> The one thing that I have learned with the redistribution is applying the
> metrics. For EIGRP, you must apply the metrics either as a default in the
> routing process or on the redistribute command line. You cannot solely do
> this within the metric. Here is an example of a route-map for redistribution
> that I have used:
>
> router eigrp 1
> redistribute ospf 1 route-map Ospf2Eigrp metric 100000 1 255 1 1500
> !
> router ospf 1
> redistribute eigrp 1 route-map Eigrp2Ospf metric 10 metric-type 1
> !
> route-map Eigrp2Ospf deny 10
> match tag 110
> !
> route-map Eigrp2Ospf permit 20
> set tag 90
> !
> route-map Ospf2Eigrp deny 10
> match tag 90
> !
> route-map Ospf2Eigrp permit 20
> set tag 110
>
>
> I am interested in any other great ways to accomplish this. You can't know
> enough of the ways to do things.
>
> Dave
> -----Original Message-----
> From: nobody@groupstudy.com
> To: Cisco Nuts
> Cc: ccielab@groupstudy.com
> Sent: 11/5/2005 10:13 AM
> Subject: Re: Rip <--->Ospf Redistribution - using distribute-lists?
>
> Both using distance and or distribute lists is a valid way
> of stopping the loops. The advantage of the distance way
> where possible is you do not have to maintain ACLs so
> as new routes get advertised you do not have to update
> the ACL's.
>
> It is not always possible to use distance on its own.
>
> Regards
> Kevin
>
> On 11/5/05, Cisco Nuts <cisconuts@hotmail.com> wrote:
> > Hello: Is distribute-lists a good idea to use when doing 2-way
> > redistribution b/w Rip and Ospf or for that matter b/w any 2 IGP's in
> > general? I have been reading a very good example of this on CCO but
> did
> > not run into this kind of solution (if I recall correctly) when doing
> the
> > InetExp Labs. Even a sample lab from DoIt uses the distance 109 for
> RIP.
> > Permitting all RIP routes into Ospf via the distribute-list out rip
> under
> > Ospf while denying all RIP routes in via the distribute-list out ospf
> > under Rip seems to nail it down. Any thoughts on this? Thanks!!
> >
> >
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