From: Larry Roberts (groupstudy@american-hero.com)
Date: Thu Jun 23 2005 - 16:54:40 GMT-3
I have been trying to research this topic to observe the behavior, but
for the life of me I can't get the forwarding address to be zero's.
I have tried 2 different IOS trains, and 2 different routing protocols
(RIP and ISIS).
My routes redistributed from OSPF into another protocol all show up with
the redis point being the next hop.
However I am completely unable to get my E2 routes to have a forwarding
address of zero's.
I just finished reading the relevant parts of the OSPF v2 RFC and It
*should* work. But I just cant get it to work.
There was another thread on this titled " /32 vs /24 for loopback and
OSPF" in which a link to a netmaster document titled "Forwarding
behavior of IGP Routing Protocols on a Broadcast Subnet Part one" was
given. I have even cut and paste the configuration and it doesn't work.
Somebody tell me I'm not going crazy here..
ccie2be wrote:
>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
>>
>>
>
>_______________________________________________________________________
>Subscription information may be found at:
>http://www.groupstudy.com/list/CCIELab.html
>
>_______________________________________________________________________
>Subscription information may be found at:
>http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Wed Jul 06 2005 - 14:43:42 GMT-3