It comes down to version of IOS.
Pre 12.0 code didn't deal with class-less subnets well. 12.0 and higher
deal with them better, but still isn't perfect.
If you don't match your exact IP address mask with a direct compliment
of a network statement in OSPF you are asking for trouble. Some of the
problems that may occur include things such as when you put the entry
for the interface in it properly advertises, but if the interface flaps
the route might not be pulled or might not be restored. Then ere is the
CIDR bug in pre 12.0 images where if you supernet a class-full address
range the advertisement doesn't work.
Redistribution is a hack to work around these issues, and induces it's
own problems and issues.
You mileage may vary.
David
-----Original Message-----
From: Chris Davis [mailto:chris.davis@computerjobs.com]
Sent: Tuesday, May 22, 2001 10:05 AM
To: cisco-nsp@puck.nether.net
Subject: RE: [nsp] OSPF not distributing 1 interface
I took the official Cisco BSCN training course last year, covering this
topic. The instructor explained that OSPF can be a bit kooky and won't
always pick up connected networks without the redistribute statement.
He
didn't offer details as to why, but apparently it's common behavior.
-----Original Message-----
From: ken lindahl [mailto:lindahl@ack.Berkeley.EDU]
Sent: Tuesday, May 22, 2001 12:30 PM
To: cisco-nsp@puck.nether.net
Subject: RE: [nsp] OSPF not distributing 1 interface
i keep wondering what i'm missing. as i read it, the original report
states that the /30 ethernet between the two routers is in the ospf
area, but the /30 route does not appear in the route table. if the
/30 is in the ospf area, the /30 should appear in the routing table
by default; no redistribute statement should be necessary. the
discussion of redistribute seems to ignore that fundamental discrepency.
i think this is what Zaheer Aziz was getting at, and in addition to
the two diagnostic statement recommended by Zaheer:
>> > > sh ip route 10.0.16.30
>> > > sh ip ospf database router <router ID of R1>,
i suggest:
sho ip ospf neighbor
i also think it would be helpful to see more of the router
configurations,
since there is clearly something critical not being revealed.
ken
On Mon, 21 May 2001, George Robbins <grr@shandakor.tharsis.com> wrote:
>Right, but the bottom line is that "connected" and/or "static"
>routes don't become known to ospf until they're redistributed
>into ospf. Routes may heard over the interface once an adjacency
>is established, but in this case neither router is feeding any
>routes into ospf, so there's nothing to pass.
>
>Other routes may exsit in the environment beyond what are explictly
>in the configuration, PPP negotation may inject a /32 for the peer
>address, OSPF may create internal routes (this isn't clear) to
>adjacent neighbors.
>
>And the usuaul reminder with OPSF, add a loopback to the configuration
>for OSPF to pick up as the router-id or specifiy a router ID so that
>OSPF does not pick one at random.
>
> George
>
>> From cisco-nsp-request@puck.nether.net Mon May 21 22:01:31 2001
>> Resent-Date: Mon, 21 May 2001 22:01:19 -0400
>> Received-Date: Mon, 21 May 2001 21:55:36 -0400
>> X-Sender: zaziz@ce-nfs-1.cisco.com
>> Date: Mon, 21 May 2001 18:54:00 -0700
>> To: Charles Sprickman <spork@inch.com>
>> From: Zaheer Aziz <zaziz@cisco.com>
>> Subject: RE: [nsp] OSPF not distributing 1 interface
>> Cc: Barry Wright <Bwright@interland.com>,
>> "'Chris Davis'" <chris.davis@computerjobs.com>,
>> "'steven.godfrey@intechnology.co.uk'"
<steven.godfrey@intechnology.co.uk>,
>> <cisco-nsp@puck.nether.net>
>> In-Reply-To:
<Pine.BSF.4.33.0105211929520.17664-100000@shell.inch.com>
>> References: <4.3.2.7.2.20010521155218.02ed3708@ce-nfs-1.cisco.com>
>> Resent-From: cisco-nsp@puck.nether.net
>> X-Mailing-List: <cisco-nsp@puck.nether.net> archive/latest/6376
>> X-Loop: cisco-nsp@puck.nether.net
>> Precedence: list
>> Resent-Sender: cisco-nsp-request@puck.nether.net
>>
>> At 07:31 PM 5/21/2001 -0400, Charles Sprickman wrote:
>> >On Mon, 21 May 2001, Zaheer Aziz wrote:
>> >
>> > > Steve,
>> > >
>> > > The redistribute trick will work, but question remains why the
network
>> > > statement under ospf is
>> > > not picking up this interface.
>> >
>> >I thought that the network statement was only to describe which
interfaces
>> >would be in the ospf area. Is this incorrect?
>>
>> It is correct but in addition it does a lot more
>> e.g.
>>
>> detects ospf neighbors on that interface
>> advertise the subnet of that interface via is Router Link State
>> advertisement (LSA)
>> exchange OSPF LSAs to the neighbors on that interface
>>
>> Zaheer
>>
>>
>> >Thanks,
>> >
>> >Charles
>> >
>> > > taking a look at database and routing table may be good start
>> > >
>> > > please provide
>> > >
>> > > sh ip route 10.0.16.30
>> > > sh ip ospf database router <router ID of R1>,
>> > >
>> > > repeat for R2
>> > >
>> > > It may have been the case that OSPF did not pick this interface
by
mistake,
>> > > removing the network statement and
>> > > reinsertion may trigger it
>> > >
>> > > Hope this helps
>> > > Zaheer
>> > >
>> > >
>> > >
>> > > >-----Original Message-----
>> > > >From: Chris Davis [mailto:chris.davis@computerjobs.com]
>> > > >Sent: Monday, May 21, 2001 12:45 PM
>> > > >To: 'steven.godfrey@intechnology.co.uk';
cisco-nsp@puck.nether.net
>> > > >Subject: RE: [nsp] OSPF not distributing 1 interface
>> > > >
>> > > >
>> > > >Hello,
>> > > >
>> > > >Try "redistribute static subnets" under "router ospf 10"
>> > > >
>> > > >Chris Davis
>> > > >Site Engineer
>> > > >www.ComputerJobs.com
>> > > >Upgrade Your Future
>> > > >
>> > > >
>> > > >
>> > > >-----Original Message-----
>> > > >From: Freeserve (E-mail) [mailto:steve@godus.freeserve.co.uk]
>> > > >Sent: Monday, May 21, 2001 12:26 PM
>> > > >To: cisco-nsp@puck.nether.net
>> > > >Subject: [nsp] OSPF not distributing 1 interface
>> > > >
>> > > >
>> > > >Hi,
>> > > >I have a strange problem with OSPF.
>> > > >
>> > > >The config is a very simple one area, one network statement. I
have
a /30
>> > > >joining to routers over Ethernet and basically neither of the
routers is
>> > > >redistributing this connected link into OPSF?
>> > > >
>> > > >The 2 routers have other connections in the same network range
and
>> > these are
>> > > >being redistributed ok to the other 10 routers on the network?
>> > > >
>> > > >If anyone has any ideas I would appreciate it.
>> > > >
>> > > >Here is the config:
>> > > >
>> > > >ROUTER 1:
>> > > >
>> > > >interface FastEthernet0/0
>> > > > description ******* HG1-PE4 ********
>> > > > ip address 10.0.16.30 255.255.255.252
>> > > > ip ospf cost 5
>> > > > duplex auto
>> > > > speed auto
>> > > > tag-switching mtu 1600
>> > > > tag-switching ip
>> > > > no cdp enable
>> > > >
>> > > >router ospf 10
>> > > > log-adjacency-changes
>> > > > network 10.0.0.0 0.255.255.255 area 0.0.0.0
>> > > >
>> > > >
>> > > >ROUTER 2:
>> > > >
>> > > >interface FastEthernet2/1
>> > > > description ****** HG1-PE5 ******
>> > > > ip address 10.0.16.29 255.255.255.252
>> > > > ip ospf cost 5
>> > > > duplex auto
>> > > > speed auto
>> > > > tag-switching mtu 1600
>> > > > tag-switching ip
>> > > >
>> > > >router ospf 10
>> > > > log-adjacency-changes
>> > > > passive-interface Serial3/0.2
>> > > > network 10.0.0.0 0.255.255.255 area 0.0.0.0
>> > > >
>> > > >Thanks in advance
>> > > >
>> > > >Steve.
>> > >
>>
>>
>
>
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