From: Johan Strandloof (strandloof@xxxxxxxxx)
Date: Fri May 24 2002 - 15:14:00 GMT-3
Make the router an ABR by creating a new area. Create a loopback like
170.100.100.100/32 and place it in the new area.
Now use the area range command to summarize the area and you got your
null route.
I have used this a few times and it works fine to my knowledge.
Cheers
Johan
On Fri, 24 May 2002 09:07:00 -0700
Jeongwoo Park <jpark@wams.com> wrote:
> Jason
> I don't think I understood what you said.
> My ios version is 12.0, and this router is ASBR. So, somehow I need
> something like this' ip route 170.100.100.0 255.255.255.0 null0'
> Area range is used only in ABR as far as I know. So, I can't use area range
> command to summarize the route with 27 subnet mask.
> I used the command 'summary-address'
> If I put static route to null 0, it works beautifully. But since the static
> route to null 0 is considered static route, I won't be allowed to use it.
> Would I have other options that are as good as using static route to Null 0?
>
> Thanks
>
> -----Original Message-----
> From: li jian hua [mailto:jasonli@cisco.com]
> Sent: Thursday, May 23, 2002 9:46 PM
> To: Jeongwoo Park
> Cc: 'ccielab@groupstudy.com'
> Subject: Re: Work-around on using null interface
>
> Prior to Cisco IOS? Software Release 12.1(6), it was recommended to
> manually configure, on the ABR, a discard static route for the summary
> address in order to prevent possible routing loops. For the summary route
> shown above, you can use this command:
> ip route 128.213.64.0 255.255.224.0 null0
> In IOS 12.1(6) and higher, the discard route is automatically generated by
> default. If for any reason you don't want to use this discard route, you
> can configure the following commands under router ospf:
> [no] discard-route internal
> or
> [no] discard-route external
>
>
>
> At 20:36 2002-5-23 -0700, Jeongwoo Park wrote:
> >Hi
> >I was wondering what could be equivalent to using null interface.
> >I was redistributing ospf route 170.100.100.6/27 into igrp with the summary
> >address of 170.100.100.0/24.
> >Once you summary under ospf, it is a must that you should use null
> >interface( ip route 170.100.100.0 255.255.255.0 null 0). Since using null
> >interface is considered static route, what could be the substitute for
> that?
> >I tried with distribute-list, but didn't work.
> >
> >Thanks
> >
> >JP
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