RE: [nsp] Filtering OSPF

From: Gyorfy, Shawn (sgyorfy@elinkny.com)
Date: Tue Mar 19 2002 - 15:16:55 EST


I have that, the access routers are getting the default routes where I want
them to be getting them from, but they are also getting tons of other routes
they don't need to be getting.

Where I am going with this.. The access routers have different IP address
from all different schemes (can't summarize.. arrg). I do NOT want to put
all static routes because of management purposes. The access routers are
only single-homed. If I use OSPF, like I am now, the access routers get all
of the other OSPF routes from the other access routers in that area. The
access routers don't have to talk to each other. Therefore I don't need
their route in other access-routers. But I like the convergence and routing
table at my border router. My border router populates all of the OSPF
routes and distributes them via BGP into other routers.

Example: Border Router
router ospf 1
 log-adjacency-changes
 area 10.111.64.0 nssa default-information-originate no-summary
 area 10.111.64.0 range 10.111.64.0 255.255.248.0
 area 10.111.72.0 nssa default-information-originate no-summary
 area 10.111.72.0 range 10.111.72.0 255.255.248.0
 area 10.111.80.0 nssa default-information-originate no-summary
 area 10.111.80.0 range 10.111.80.0 255.255.248.0
 area 10.111.120.0 nssa default-information-originate no-summary
 area 10.111.120.0 range 10.111.120.0 255.255.248.0
 redistribute static subnets
 network 10.111.64.0 0.0.7.255 area 10.111.64.0
 network 10.111.72.0 0.0.7.255 area 10.111.72.0
 network 10.111.80.0 0.0.7.255 area 10.111.80.0
 network 10.111.120.0 0.0.7.255 area 10.111.120.0

ACCESS ROUTER:
router ospf 1
 log-adjacency-changes
 area 10.111.120.0 nssa no-summary
 redistribute static subnets
 passive-interface FastEthernet0
 network 10.111.120.124 0.0.0.3 area 10.111.120.0
 network 10.111.120.128 0.0.0.3 area 10.111.120.0
 network 20X.X.X.X 0.0.0.255 area 10.111.120.0
 network 20X.X.X.X 0.0.0.63 area 10.111.120.0

GETTING DEFAULT ROUTE (ACCESS ROUTER):
Routing entry for 0.0.0.0/0, supernet
  Known via "ospf 1", distance 110, metric 1, candidate default path, type
NSSA extern 2, forward metric 65
  Redistributing via ospf 1
  Last update from 10.111.120.125 on Serial0, 00:00:31 ago
  Routing Descriptor Blocks:
    10.111.120.129, from 20X.X.X.X, 00:00:31 ago, via Serial1
      Route metric is 1, traffic share count is 1
  * 10.111.120.125, from 20X.X.X.X, 00:00:31 ago, via Serial0
      Route metric is 1, traffic share count is 1

-----Original Message-----
From: Mark Pace Balzan [mailto:mpb@melitacable.com]
Sent: Tuesday, March 19, 2002 3:06 PM
To: Gyorfy, Shawn; cisco-nsp@puck.nether.net
Subject: Re: [nsp] Filtering OSPF

most likely you should be looking at 'default-originate' in you 'router ospf
<area>' config

----- Original Message -----
From: "Gyorfy, Shawn" <sgyorfy@elinkny.com>
To: <cisco-nsp@puck.nether.net>
Sent: Tuesday, March 19, 2002 8:57 PM
Subject: [nsp] Filtering OSPF

> Question:
> Using Cisco equipment:
>
>
> I have 4 OSPF Areas with X number of routers per area. As of right now
the
> access routers are getting a full routing table from the border router as
> per their appropriate area. I would like to limit their routing table so
> they only get the default route. I am looking at distribution list, am I
> hot on this one or still cold?
>
>
> shawn
>
>
>



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