RE: Filtering/Poisoning ISIS injected 0.0.0.0/0 default route

From: ccie2be (ccie2be@nyc.rr.com)
Date: Mon May 30 2005 - 13:05:43 GMT-3

Long,

What happens if you configure, no set-attach-bit under the isis routing
process? Doesn't that prevent the default route from being advertised from
a L1/L2 router to a L1 router?

Tim

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Long
Kwok
Sent: Monday, May 30, 2005 11:58 AM
To: Bob Sinclair; ccielab@groupstudy.com
Subject: RE: Filtering/Poisoning ISIS injected 0.0.0.0/0 default route from
L1 internal routers

Thanks Bob,

I believe though that when you set the attatched bit doesn't this tell a
router to send a default route into L1 only devices ? I was doing a lab
that was not permitted to have any form of default 0/0 routes on any
routers unless explicitly permitted , and within the isis topology ,
there was an L1/L2 router then behind this L1/L2 router is a few L1
only routers , I believe by default this L1/L2 ABR if you will ,
automatically injects a 0/0 route to its internal L1 only
bretherin...... Thanks so much for reply Bob

TIA Long

  _____

From: Bob Sinclair [mailto:bsin@cox.net]
Sent: Monday, May 30, 2005 5:47 AM
To: Long Kwok; ccielab@groupstudy.com
Subject: Re: Filtering/Poisoning ISIS injected 0.0.0.0/0 default route
from L1 internal routers

Long Kwok,

Here is a config and link that permits conditional setting of the
attached bit. I wonder if something along these lines would help.

!
router isis
 net 39.0001.0000.0000.7201.00
 set-attached-bit route-map CONDITION
!
route-map CONDITION
match int loop101
http://www.cisco.com/warp/public/cc/pd/iosw/prodlit/isis_an.htm
Bob Sinclair

CCIE #10427, CCSI 30427, CISSP

www.netmasterclass.net

        ----- Original Message -----

        From: Long Kwok <mailto:lkwok@ccieunix.com>

        To: ccielab@groupstudy.com

        Sent: Sunday, May 29, 2005 3:03 PM

        Subject: Filtering/Poisoning ISIS injected 0.0.0.0/0 default
route from L1 internal routers

        Hi,

        I have been trying to filter out the automatically injected
0.0.0.0/0
        route that the L2 border router injects into its L1 internal
neighbors
        as I guess it would be considered cheating on lab and you cannot
do that
        I was trying to filter via distance 255 under L1 routers isis
router
        process but not working. Here is what I tried.

        Router isis

          Distance 255 0.0.0.0 255.255.255.255 1

        Access-list 1 deny 0.0.0.0 0.0.0.0

        Tia Long

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