From: Williams, Glenn (WILLIAMSG@xxxxxxxxxxxxx)
Date: Wed Jan 02 2002 - 12:26:41 GMT-3
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
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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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