From: Peter van Oene (pvo@xxxxxxxxxxxx)
Date: Wed Jan 02 2002 - 16:29:55 GMT-3
Not sure what's odd about this. In general, specificity brings finer
control.
At 10:26 AM 1/2/2002 -0500, Williams, Glenn wrote:
>Thanks. So it seems that applying a less specific mask, that is 0.0.0.255
>vs 0.0.0.0 could be more harmful in this situation. Odd.
>
>GW
>
>-----Original Message-----
>From: Waters, Kivas (UK72) [mailto:Kivas.Waters@Honeywell.com]
>Sent: Wednesday, January 02, 2002 9:25 AM
>To: Williams, Glenn
>Subject: RE: Simple OSPF question
>
>
>Hi Glenn, I have never personally had any problem with the 0.0.0.0 OSPF
>inverse mask but it seems that others on groupstudy have. Check out the
>below emails ... By the way, if you get chance to test Ben's theory please
>let me know your results.
>
>regards
>
>Ki
>
>-----Original Message-----
>From: R. Benjamin Kessler [mailto:ben@kesslerconsulting.com]
>Sent: 17 December 2001 23:07
>To: Nguyen, Thai; ccielab@groupstudy.com
>Subject: RE: Defining network number under ospf process
>
>
>Sorry, I'm coming in a little late on this one...
>
>My understanding is that if you have a vanilla OSPF environment it doesn't
>matter which one you select. Some of us prefer to nail-down the address
>very specifically (by using the 0.0.0.0 exact match wildcard mask). It was
>pointed-out to me last week that there may be some situations where this
>produces undesirable results - specifically in redistribution.
>
>If I have a network like the following:
>
> R4 R1
> | |
> ----+-------+-------+-------+----
> | |
> R2 R3
>
>R1, R2, and R3 are in OSPF area 0 on an Ethernet segment.
>R4 is also on the Ethernet segment and along with R1 is in an IGRP AS
>
>If all of the OSPF speakers are configured with the 0.0.0.0 reverse mask on
>their network statements when R1 redistributes the IGRP routes into OSPF
>R1's IP address will appear as the next-hop in the routing tables of R2 and
>R3.
>
>If the configuration of R1 is modified to match the reverse mask of the
>subnet then the other OSPF speakers see R4's ip address as the next-hop. It
>didn't seem to matter how the wildcard masks on the other routers were
>configured only the redistributing router.
>
>I set this up with R1 as the DR and R2 as the BDR; the OSPF state of the
>router's interface (DR, BDR, DROTHER) didn't seem to matter as I reproduced
>these results with R3 as the redistribution router.
>
>I don't know if this clears things up or confuses you more, you may want to
>play around with it in your lab until it is clear in your mind.
>
>Hope this helps.
>
>Ben
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>Nguyen, Thai
>Sent: Monday, December 10, 2001 6:07 PM
>To: ccielab@groupstudy.com
>Subject: Defining network number under ospf process
>
>
>Hi all
>
>I am having trouble of knowing the difference between the following
>configuration.
>
>int e0
>ip add 1.1.1.1 255.255.255.0
>
>router ospf 1
>network 1.1.1.1 0.0.0.0 area 1
>
>
>router ospf 1
>network 1.1.1.0 0.0.0.255 area 1
>
>Can anyone offer me an advise.
>
>Thanks.
>
>
>Thai Nguyen
>Senior Networking Engineer
>IT Delivery
>Australia Post
>03 9204 5309
>
>Australia Post is committed to providing our customers with excellent
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>-----Original Message-----
>From: Williams, Glenn [mailto:WILLIAMSG@PANASONIC.COM]
>Sent: 02 January 2002 14:51
>To: 'ccielab@groupstudy.com'
>Subject: Simple OSPF question
>
>
>Hi,
>
>Usually when I enable ospf on an interface, for example if the interface is
>137.20.20.1/24, I would say:
>
>net 137.20.20.1 0.0.0.0 area x
>
>I could say:
>
>net 137.20.20.0 0.0.0.255 area x
>
>but what would I gain?
>
>Just one of those questions I've been meaning to ask.
>
>GW
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