From: Volkov, Dmitry (Toronto - BCE) (dmitry_volkov@ca.ml.com)
Date: Thu Sep 05 2002 - 02:33:02 GMT-3
> -----Original Message-----
> From: Nick Shah [mailto:nshah@connect.com.au]
> Sent: Thursday, September 05, 2002 1:10 AM
> To: Volkov, Dmitry (Toronto - BCE)
> Cc: frank.yu@japan.bnpparibas.com; ccielab@groupstudy.com
> Subject: Re: redistribute ospf to igrp again
>
>
> Further to what has already been discussed :
> The question to ask yourself and the proctor is what is
> allowed and what is
> not ?
>
> * Check if default network is permitted, if so, and if you can get a
> classful network to play with, nothing better.
>
> * Check for all possibilities of generating area-ranges &
> summaries (Area
> range is possible only on ABRs and summary is possible only
> on ASBR), So if
> a router is not an ABR, think if you can make it one, or if
> its not an ASBR
> can you make it one. In this case (especially one mentioned
> below) you can
> use 172.16.0.4/30 assign it to a dummy interface, do a redistribution
> (connected etc.) and make an ASBR, and then do the summary
> stuff. This would
> only work if the other subnets of 172.16.0.0/24 are not in
> use elsewhere.
>
> * Check if the topology permits creating area ranges, mostly
> it does, and
> that will save the day.
>
> * With RIP , secondary addressing work well. Because you can
> have RIP honour
> the secondary address masks, and also learn addresses with
> those masks on
> the other side. With IGRP, its ugly, you have to be careful,
> mostly if used
> on both ends it summarizes to the mask of the primary ip
> address. (I still
> have to try what Dmitry has mentioned here)
There was one mistake in my initialy proposed solution...
I forgot to say to put sec address 172.16.0.x (/xx) on R2 interface faced to
R3.
In this case igrp being ruuning on 172.16.0.0/16 will redistr network
defined by this secondary into ospf and make LSA 5 in ospf.
After that to put "summary-address 172.16.0.0 255.255.255.0" under OSPF
process on R2
And this 172.16.0.0/24 will go to R3. This works (just repeated again).
But this is too ugly.
It's much better to assign 172.16.0.x/24 (for example) on R2 interface
(don't run ospf on it) faced to R1 and don't do anything else. (maybe to
filter it from redistr into ospf)
In both cases I meant to put only one sec address on R2. Nothing on R3 !
Dmitry
>
> * Tunnels have been suggested by Faraz Shamim, author of T'shooting IP
> routing protocols as appropriate when dealing with IGRP especially.
>
> * Then there are other 'dirty tricks', of creating second
> instance of OSPF,
> redistributing into the first one. But that is mostly done to
> create an
> ASBR.
>
> So the trick when using OSPF is to see how you can get it to cough up
> 'summaries' whether by making it ABR or ASBR or tunnels or secondary
> addressing.
>
> rgds
> Nick
>
>
> ----- Original Message -----
> From: "Volkov, Dmitry (Toronto - BCE)" <dmitry_volkov@ca.ml.com>
> To: "'Omer Ansari'" <omer@ansari.com>
> Cc: <frank.yu@japan.bnpparibas.com>; <ccielab@groupstudy.com>
> Sent: Thursday, September 05, 2002 2:03 PM
> Subject: RE: redistribute ospf to igrp again
>
>
> > > howdy,
> > >
> > > two questions:
> > >
> > > 1. amongst the VLSM/FLSM resolution techniques, i've
> > > heard/tried several
> > > options:
> > >
> > > secondary address
> > > tunnelling
> > > area X range/summary-address
> > > ip summary-address eigrp
> > > etc etc..
> > >
> > > is the touted secondary address solution the one you
> presented below?
> > >
> > > also, my reasoning behind its working:
> > > note that the /30 route is in the IGRP db also on the
> ASBR, however,
> > > when it gets redist'ed to OSPF, ospf rejects it because it
> > > already sees
> > > this route as connected..however a secondary address on which
> > > ospf is not
> > > running, would then get redist'ed into ospf, seen as an
> External LSA.
> > > and then the summary-address would do its magic.
> > >
> > > in other words if we had
> > > router ospf X
> > > network 172.16.0.0 0.0.255.255 area X
> > >
> > > this solution would not work. correct?
> >
> > heh, buddy, too complex. It's too late in Toronto already :)
> > Everything much easier:
> > I meant assign sec address 172.16.0.1/24 (for example) on
> R2 interface
> > (don't run ospf on it)
> > faced to R1 (to avoid split hor issues). It's the same
> major net, hence
> it's
> > just known by IGRP without any redistribution, the same
> mask, the same
> major
> > - what else do we need ?
> > Net 172.16.0.0/24 will be in R3.
> >
> >
> > > 2. remember we once discussed this, when you and I were
> learning this
> > > method, and i mentioned using a loopback interface for
> > > 172.16.0.1/24 but
> > > the idea was shot down.
> >
> > The same stuff as secondary. It depends what is allowed (if any ;)
> >
> > Dmitry
> >
> >
> > > just want to make sure why that would be a bad idea, b/c
> i still like
> > > using it :)
> > >
> > > regards,
> > > Omer
> > >
> > > On Wed, 4 Sep 2002, Volkov, Dmitry (Toronto - BCE) wrote:
> > >
> > > > Hello,
> > > >
> > > > Since R2 is not ABR but ASBR we can not use area range command.
> > > > I case if You are doing redistr between OSPF and IGRP You
> > > can just put
> > > > "summary-address 172.16.0.0 255.255.255.0" under OSPF
> process on R2
> > > > It will create automatically route to Null
> > > > This route will be propagated into IGRP.
> > > > You can also just put secondary address (like
> > > 172.16.0.1/24) on R2 interface
> > > > faced to R1
> > > >
> > > > Dmitry
> > > >
> > > > > -----Original Message-----
> > > > > From: elping [mailto:elpingu@acedsl.com]
> > > > > Sent: Tuesday, September 03, 2002 12:37 AM
> > > > > To: frank.yu@japan.bnpparibas.com
> > > > > Cc: ccielab@groupstudy.com
> > > > > Subject: Re: redistribute ospf to igrp again
> > > > >
> > > > >
> > > > > do an area range command for the /30
> > > > >
> > > > > frank.yu@japan.bnpparibas.com wrote:
> > > > >
> > > > > > Group,
> > > > > >
> > > > > > As you can see the following diagram, R2 is ospf
> > > > > ASBR and running
> > > > > > igrp too.
> > > > > > My question is how can R3 reach ospf area0, except
> > > > > R2 advertising a
> > > > > > default route to igrp?
> > > > > > Is there a way for R2 to summary the ospf backbone
> > > > > into 24bit route
> > > > > > and redistribute it to igrp domain?
> > > > > > Thanks!
> > > > > >
> > > > > > 172.16.0.0/30 172.16.1.0/24
> > > > > > R1-------------------R2--------------------R3
> > > > > > ospf area0 igrp
> > > > > >
> > > > > > Frank
> > > > > >
> > > > > > This message and any attachments (the "message") is
> > > > > > intended solely for the addressees and is confidential.
> > > > > > If you receive this message in error, please delete it and
> > > > > > immediately notify the sender. Any use not in accord with
> > > > > > its purpose, any dissemination or disclosure, either whole
> > > > > > or partial, is prohibited except formal approval.
> The internet
> > > > > > can not guarantee the integrity of this message.
> > > > > > BNP PARIBAS (and its subsidiaries) shall (will) not
> > > > > > therefore be liable for the message if modified.
> > > > > >
> > > > > >
> ---------------------------------------------
> > > > > >
> > > > > > Ce message et toutes les pieces jointes (ci-apres le
> > > > > > "message") sont etablis a l'intention exclusive de ses
> > > > > > destinataires et sont confidentiels. Si vous recevez ce
> > > > > > message par erreur, merci de le detruire et d'en avertir
> > > > > > immediatement l'expediteur. Toute utilisation de ce
> > > > > > message non conforme a sa destination, toute diffusion
> > > > > > ou toute publication, totale ou partielle, est
> interdite, sauf
> > > > > > autorisation expresse. L'internet ne permettant pas
> > > > > > d'assurer l'integrite de ce message, BNP PARIBAS (et ses
> > > > > > filiales) decline(nt) toute responsabilite au titre de ce
> > > > > > message, dans l'hypothese ou il aurait ete modifie.
This archive was generated by hypermail 2.1.4 : Mon Oct 07 2002 - 07:43:44 GMT-3