From: Jerry Haverkos (jhaverkos@xxxxxxxxxxxxxxx)
Date: Fri May 24 2002 - 16:05:04 GMT-3
Everyone
In my lab I have made such a null address by defining a Loopback Interface
and then doing summarization on that interface. The Summarization creates
the null route.
In looking back I found the following from a working lab. The summary
address is not even related to the interface to which it is applied. The
null route is still made and shows up in the routing table.
interface Loopback0
ip address 10.1.32.1 255.255.255.255
ip summary-address eigrp 14 0.0.0.0 0.0.0.0
grandpa jerry
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Johan Strandloof
Sent: Friday, May 24, 2002 2:14 PM
To: Jeongwoo Park; 'ccielab@groupstudy.com'
Subject: Re: Work-around on using null interface
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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