From: P729 (p729@xxxxxxx)
Date: Sat Jul 13 2002 - 18:02:31 GMT-3
At least with 12.2(10a):
r2(config-router)#summary-address 152.1.11.0 0.0.0.255
OSPF: Invalid address/mask combination (discontiguous mask)
But we all know that the parser has, uh, evolved over time (re-ordering of
network statements, adjusting network/mask in ACLs, etc.)
Mayande, what version of IOS was involved?
Regards,
Mas Kato
https://ecardfile.com/id/mkato
----- Original Message -----
From: "Yakout esmat" <yesmat@iprimus.com.au>
To: "ccie candidate" <ccie1@lycos.com>; <ccielab@groupstudy.com>; "Mayande
P.Gowon" <bustahnet@usa.net>
Cc: <mayande@itochu.net>
Sent: Saturday, July 13, 2002 5:19 AM
Subject: RE: summary-address creates default gateway
> That's strange, because you wouldn't be able to use inverse mask with
> summary-address command, you will get an error message, and the parser
> wouldn't let you do that...
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> ccie candidate
> Sent: Saturday, July 13, 2002 7:31 PM
> To: ccielab@groupstudy.com; Mayande P.Gowon
> Cc: mayande@itochu.net
> Subject: Re: summary-address creates default gateway
>
>
> the wrong mask which you have used is actual create a summary address for
> the default route .
>
> 0.0.0.255 if you match it against the subnet you used ..it will lead to
> 0.0.0.0 /0.
> the comment of Mas kato is worth to try if other masks will create also
the
> same default network
>
>
> --
>
> On Fri, 12 Jul 2002 13:58:22
> Mayande P.Gowon wrote:
> >I'm hoping someone will be able to provide me with some insight
> >on the following:
> > I was working on a redistributing IGRP & OSPF lab the other night when I
> came
> >across something that I'm unclear about any thoughts or explanations
would
> be
> >appreciated:
> >
> > lo0--A----B----C-----D----lo0
> >There were 4 routers - A, B, C, D. The serial interfaces between A & B
are
> in
> >OSPF area 1, the serial interfaces between B & C are in OSPF area 0, and
> the
> >link between C and D are IGRP.
> >This is a VLSM/FLSM scenario (IGRP has /24 mask, and OSPF has various).
The
> >lo0 of A is being redistributed (redistribute connected subnets) into
OSPF,
> >because it is a /28 I performed a summary-address command to advertise it
> as a
> >/24 to IGRP. All of this worked fine in the end without issue...but the
> first
> >time I performed the summary command I accidently used the wrong subnet
> mask.
> >
> > Instead of "summary-address 152.1.11.0 255.255.255.0" I typed
> >"summary-address 152.1.11.0 0.0.0.255". This created a default null route
> >(0.0.0/0) which propogated across the entire OSPF network! In other words
> >routers B and C now had a default gateway pointing to the null route
> 0.0.0.0/0
> >on router A.
> >This seems like a neat trick as this default gateway gets propogated
across
> >the OSPF network and without creating a static route. I however don't
> really
> >understand what caused this to happen...any insight?
This archive was generated by hypermail 2.1.4 : Sat Sep 07 2002 - 19:36:29 GMT-3