From: ccie2be (ccie2be@nyc.rr.com)
Date: Wed May 18 2005 - 12:36:40 GMT-3
Hi guys,
I learned the answer to this fairly obscure feature just a couple weeks ago.
Here's the reason. Suppose this is your topology:
r1
|------------------|-----------------|
| |
r2 r3
isis ospf
r1 is redist between isis and ospf. If you want the next hop of routes that
r3 learns from r2 indirectly via r1 to be r2, then don't use a wildcard mask
of 0.0.0.0 on R1's interface to the common segment. If you do, then packets
from r3 going to r2 or beyond will make a pit stop at r1. This is obviously
inefficient, so in such a scenario, it's better and more efficient to use a
wildcard mask on r1 that isn't 0.0.0.0
If you have a chance, try to lab it up and see for yourself.
HTH, Tim
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Anthony Sequeira
Sent: Wednesday, May 18, 2005 11:13 AM
To: Dennis J. Hartmann
Cc: ccielab@groupstudy.com
Subject: Re: OSPF 0.0.0.0 wildcard (inverse) mask
I would love to hear the reasoning behind this - for the Practical Lab
- I plan on using the 0.0.0.0 wildcasrd mask exclusively unless I am
told to do otherwise!
On 5/18/05, Dennis J. Hartmann <dennisjhartmann@hotmail.com> wrote:
> Someone E-Mailed me a white paper on why you should never use 0.0.0.0
as
> a wildcard mask a while ago. I have misplaced it and I have a friend
> interested in taking a look at it. If anyone has this .pdf or a link to
the
> explanation on cisco.com, can you please send it? Thanks.
>
> Sincerely,
>
> Dennis J. Hartmann
>
> White Pine Communications
>
> dh8@pobox.com
>
> CCSI#23402/CCIP/CCNP/CCDP/CCNA/CCDA
>
> Cisco IP Voice Support & Design Specialist
>
> Cisco Optical, VPN & IDS Specialist
>
> MCSE
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Fri Jun 03 2005 - 10:11:58 GMT-3