From: How Ming Low (ming@xxxxxxxxxxxxxxxxxxx)
Date: Fri Jan 11 2002 - 06:38:21 GMT-3
I think that makes sense, just retry it with 20.0.0.0/8 interface
connected to another EIGRP router. I bet that it will auto-summarize
then.
Or how bout trying this, add another major class network on another
interface connected to another EIGRP neighbor. I'm sure that the
161.71.x.x summary will be added to the table - confirming the
hypothesis. i.e.
R1 s0 161.71.7.x summaries created 161.71.0.0/16,
20.0.0.0/8, 30.0.0.0/8
s1 161.71.9.x
lo0 20.0.0.x
e0 30.0.0.x
R2 e0 30.0.0.y summaries received
161.71.0.0/16, 20.0.0.0/8
regards,
Ming
-----Original Message-----
From: Rajeev Siddappa [mailto:raj_lab@yahoo.com]
Sent: Friday, January 11, 2002 5:08 PM
To: Frank B
Cc: 'ccielab'
Subject: Answer :RE: eigrp auto-summary and a null 0 route (Probably)
Frank,
I again completely agree with you.
My only concern here was why it is not doing the same
boundary summrization for 168.71.x.x network.
Hey I think we have the answer.
Probably as you said 20.x.x.x is on loop back and
EIGRP is not seeing any neighbors on that network and
thats why it is not summarizing the 168.71.x.x
network.
and sending any updates on thet network.
Pls some debug this.
Rajeev.
--- Frank B <frank@buff-net.com> wrote:
> I've seen the other responses and it seems we still
> haven't answered why
> it didn't put a route to null 0 for both 20.0.0.0
> and 168.71.0.0? I
> can't seem to crack that nut but am very
> curious...perhaps we don't have
> enough information? Any thoughts?
>
> Also, Rajeev, 1 don't think I understand that you
> don't see a classful
> boundary or what you mean by we're in the same
> router?? And I think
> there's enough information given to show that but
> possibly not enough to
> answer why there's only 1 null route installed.
>
> We're given the network statement for the 20.0.0.0
> network and the
> routing table shows 20.1.1.0/24 is configured on
> loopback 0. I submit
> this tells us this network will be advertised to
> EIGRP neighbors.
> (barring any filtering and assuming we have
> neighbors...BTW we are
> learning eigrp routes through s1 so we have at least
> 1 at ip address
> 168.71.9.1)
>
> By inspecting the routing table it's clear we have 2
> serial interfaces
> connected within the 168.71.0.0 class B address
> space. We have s0 on
> the 168.71.7.0/24 subnet and s1 on the 168.71.9.0/24
> subnet. There's
> also a network statement for 168.71.7.0 and
> 168.71.9.0 as well. The
> router will advertise other subnets within
> 168.71.0.0 network out these
> interfaces without summarization.
>
> However, the router will summarize, advertise only
> the 20.0.0.0/8 vice
> the 20.1.1.0/24 subnet, because when going out the
> s1 or s0 interfaces
> we're crossing a classful boundary with with
> 20.0.0.0/8. I'm confident
> this is correct and that we're certainly crossing
> classful boundaries in
> the given scenario. But...I have been known to
> overlook a detail or two
> from time-to-time. ;-)
>
> Frank
>
> -----Original Message-----
> From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> CCIE Lab
> Sent: Thursday, January 10, 2002 7:34 PM
> To: j killion; Steven; ccielab
> Subject: Re: eigrp auto-summary and a null 0 route
>
> good, but why didn't it also create a summary route
> to
> null for 168.71.0.0 subnets?
>
> -----Original Message-----
> From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> Steven
> Sent: Wednesday, January 09, 2002 8:51 PM
> To: ccielab
> Subject: eigrp auto-summary and a null 0 route
>
> On one router which runs eigrp only ,the config and
> route table is as
> follows,
>
> sh run
> ...
> router eigrp 1
> network 20.0.0.0
> network 168.71.7.0 0.0.0.255
> network 168.71.9.0 0.0.0.255
> no auto-summary
> no eigrp log-neighbor-changes
>
> ...
>
> 168.71.0.0/24 is subnetted, 4 subnets
> C 168.71.9.0 is directly connected, Serial1
> C 168.71.7.0 is directly connected, Serial0
> D 168.71.6.0 [90/20768000] via 168.71.9.1,
> 00:00:17, Serial1
> D 168.71.5.0 [90/20384000] via 168.71.9.1,
> 00:00:17, Serial1
> 20.0.0.0/24 is subnetted, 1 subnets
> C 20.1.1.0 is directly connected, Loopback0
>
>
> after i add "auto-summary "command under router
> eigrp 1
>
> the route table change to the following one ,
>
> 168.71.0.0/24 is subnetted, 4 subnets
> C 168.71.9.0 is directly connected, Serial1
> C 168.71.7.0 is directly connected, Serial0
> D 168.71.6.0 [90/20768000] via 168.71.9.1,
> 00:00:03, Serial1
> D 168.71.5.0 [90/20384000] via 168.71.9.1,
> 00:00:03, Serial1
> 20.0.0.0/8 is variably subnetted, 2 subnets, 2
> masks
> D 20.0.0.0/8 is a summary, 00:00:01, Null0
> C 20.1.1.0/24 is directly connected, Loopback0
>
>
> i just want to know what "D 20.0.0.0/8 is a
> summary, 00:00:01,
> Null0"
> mean.Why is it added?
>
> -----Original Message-----
> From: Rajeev Siddappa [mailto:raj_lab@yahoo.com]
> Sent: Thursday, January 10, 2002 9:36 PM
> To: Frank B; 'CCIE Lab'
> Cc: 'ccielab'; 'j killion'; 'Steven'
> Subject: RE: eigrp auto-summary and a null 0 route
>
>
> Frank, I understand.
>
> Pls see below,
>
>
> > > Auto-summarization only takes place when you
> cross
> > > classful boundaries.
>
>
> We are not crossing any classful boundaries here.
> We are still in the same router.
>
> > > You have 2 interfaces connected within the
> > > 168.71.0.0 space; so it sends
> > > advertisements out those interfaces for subnets
> > > within 168.71.0.0
>
>
> > >
> > > However, other networks advertised out those
> > > interfaces are summarized
> > > on their classful boundary. Hope this helps.
> > >
> > > Frank
>
>
>
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