From: Sean C (Upp_and_Upp@hotmail.com)
Date: Wed May 18 2005 - 14:08:30 GMT-3
Hi Anthony and Dennis,
Did that doc help? Basically, and I'll be the first to admit I could be
totally wrong on this. The way I understand it - let's say you have 3
routers, each router's F0/0 is on the same LAN and F0/0 int is in area 0 and
each router's F0/1 int is in an area just for that router (i.e. Rtr 1's F0/1
is in Area 1, Rtr 2's F0/1 is in Area 2 and Rtr 3's F0/1 is in Area 3).
Area 0 is set as a broadcast network type. Pretty much default at this
point. Let's say R1 is the DR and both R2 and R3 are just DROTHERs.
If the routers are configured with a wildcard mask of 0.0.0.0 - if something
on R2's F0/1 needs to go to R3's F0/1, R2 will forward to R1 and R1 will
send the packet to R3. R2 will not go directly to R3 - thus suboptimal
routing. If the routers are configured with wildcard masks appropriate to
their subnet mask - then R2 would go directly to R3.
Like I wrote, I could easily be wrong on this. It's been about 2 yrs since
I researched this, so you are forewarned ;-). HTH,
Sean
----- Original Message -----
From: "Sean C" <Upp_and_Upp@hotmail.com>
To: "Anthony Sequeira" <terry.francona@gmail.com>; "Dennis J. Hartmann"
<dennisjhartmann@hotmail.com>
Cc: <ccielab@groupstudy.com>
Sent: Wednesday, May 18, 2005 11:33 AM
Subject: Re: OSPF 0.0.0.0 wildcard (inverse) mask
> See if you can access NMC's public pdf files - I know there is a document
> that discusses this. The .pdf is titled "Forwarding behavior of IGP
> routing
> protocols on the broadcast part I". I'd send the link but I don't think
> it'll work. I'm including the .pdf for Dennis and Anthony but I recognize
> GS will scrub the attachment.
>
> Honestly, I've never used 0.0.0.0 for a wildcard mask in production or
> testing environments (partly due to this doc). It may be a case of tomato
> vs. tomato (uhhh - that sounds better than it reads), but I'll always use
> the proper mask. Typically, I'll just cut-and-paste what is under the
> interface and let the router do the translating.
>
> HTH,
> Sean
>
> R3#sh run int loop 103
> interface Loopback103
> ip address 172.16.103.1 255.255.255.0
> end
> R3#conf t
> R3(config)#router osp 10
> R3(config-router)#network 172.16.103.1 255.255.255.0 area 20 <--I just
> copy
> and pasted the interface command
> R3(config-router)#end
> R3#show run | begin ^router
> router ospf 10
> network 172.16.103.0 0.0.0.255 area 20
>
> ----- Original Message -----
> From: "Anthony Sequeira" <terry.francona@gmail.com>
> To: "Dennis J. Hartmann" <dennisjhartmann@hotmail.com>
> Cc: <ccielab@groupstudy.com>
> Sent: Wednesday, May 18, 2005 11:13 AM
> 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:
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