RE: OSPF Null0 DRoute

From: Jens Petter (jenseike@start.no)
Date: Sat Jul 22 2006 - 07:32:36 ART


Set the AD of the summary to 255, and it will disapere from your routing
table

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
David Redfern (AU)
Sent: 22. juli 2006 12:04
To: Victor Cappuccio; ccielab@groupstudy.com
Subject: RE: OSPF Null0 DRoute

Yeah tried using the distance command to stop the summary being installed
but even after clearing the routes its still there?
I know it works with bgp. Are you sure it works with eigrp also to stop the
summary to null0 being installed

ip summary-address eigrp 10 130.1.0.0 255.255.0.0 5

router eigrp 10
 network 54.1.1.6 0.0.0.0
 network 130.1.6.6 0.0.0.0
 distance 255 0.0.0.0 255.255.255.255 30
 no auto-summary

access-list 30 permit 130.1.0.0 0.0.255.255

Clear ip ro *

D 130.1.0.0/16 is a summary, 00:00:29, Null0

Also tried using a distribute list but it appears I cant stop the eigrp
summary from entering the routing table?

Anyone got any ideas?

Regards,
 
David Redfern

-----Original Message-----
From: Victor Cappuccio [mailto:cvictor@protokolgroup.com]
Sent: Saturday, 22 July 2006 7:09 PM
To: David Redfern (AU); ccielab@groupstudy.com
Subject: RE: OSPF Null0 DRoute

Hola David.

Did you read my last post?

<quote>
Sorry I forgot to add this:

I know that the ASBR could generate a 0/0 Route to the Ospf Domain, so
packets that comes from route that matches the Null 0 would be converted in
steam, but Saying that the ASBR does not generate the 0 route, has any sence
to keep the Null 0 Route ??
</quote>

Sorry I'm not fluent with English

And to eliminate the discard route in eigrp is by changing the
administrative of the summary to 255, In normal situation we receive the 0/0
route from other Routers and the Null 0 would cause that the route from
others not know in the range of the same supernet would be discarded.

That's ok in this Distance Vector Hibrid Routing Protocol, but it that makes
Sense with OSPF??

-----Mensaje original-----
De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de David
Redfern (AU) Enviado el: Sabado, 22 de Julio de 2006 04:17 a.m.
Para: ccielab@groupstudy.com
Asunto: RE: OSPF Null0 DRoute

I believe the side affect is that you are vulnerable to routing loops.

For example you may be following a default route to them, whilst giving them
a summary route to you. If they send traffic to a destination within that
summary that does not exist, you will follow you default back to them. They
will send it back to you via the summary, ect ect.

If you had the route to null0 you will drop any traffic that you receive
that you don't have a longer match for. Hence loop prevention.

Does anyone know a similar command or method to the discard-route
internal/external to use for eigrp to stop the null route from being
installed?

Regards,
 
David Redfern

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Victor Cappuccio
Sent: Saturday, 22 July 2006 5:06 PM
To: ccielab@groupstudy.com
Subject: OSPF Null0 DRoute

Hi Guys.

 

Have this question about summarizing external routes in OSPF and the
creation of the null0 to the summary address in the RT.

I know that I could use no discard-route external to avoid the creation of
the Null0 route, but I'm wondering what would be a side affect of this
operation. ?

 

Has any sense to create a Discard Route from a ASBR connected to other
routing Domain?

 

Thanks

Victor.-



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