From: Lupi, Guy (Guy.Lupi@xxxxxxxxxxxxx)
Date: Wed Apr 17 2002 - 00:20:59 GMT-3
Not sure what you mean with the first statement. The only reason the tunnel
is there is so that the IGRP router has a connection to a /23 in the same
classful network as the /23 you want to be advertised. So if my tunnel is
172.168.252.0/23, then the OSPF router will send the 172.168.1.0/23 to the
IGRP router, because it is now eligible to receive it. As far as getting
the /23 in using /24's, you could put secondary ip addresses on an interface
as /24's. See below:
interface serial0
ip address 172.168.1.1 255.255.255.0 secondary
ip address 172.168.2.1 255.255.255.0 secondary
ip address 172.168.1.2 255.255.254.0
Then you redistribute connected into IGRP and the router will have
connectivity to the whole /23, but the routes will appear as /24's. Of
course you are right, if you can use a default route you should, but somehow
I don't see that being an option.
-----Original Message-----
From: Gannon, Stephen [IT]
To: Lupi, Guy; 'kym blair '; 'DHSTS68@dhs.state.il.us ';
'tsabry@houston.sns.slb.com '; 'dan_schaw@yahoo.com '
Cc: 'ccielab@groupstudy.com '
Sent: 4/16/2002 11:03 PM
Subject: RE: OSPF - IGRP and /23?
Using the tunnel approach you describe below, I would think that the /23
is
advertised to the router with the tunnel endpoint but no further into
the
RIP/IGRP domain. Correct?
I guess the wording of the question will be the key. Does the RIP
router
need the route in its table or just connectivity to the /23 network. If
you
just need connectivity send a default.
How would you go about passing 2 class C networks summarized to
199.172.12.0/23 into RIP/IGRP across that same 172.168.12.0/24 link?
O*E2 199.172.12.0/23 [110/50] via 172.168.1.3, 1d00h, Serial0
SG
-----Original Message-----
From: Lupi, Guy [mailto:Guy.Lupi@eurekaggn.com]
Sent: Tuesday, April 16, 2002 9:23 PM
To: 'kym blair '; 'DHSTS68@dhs.state.il.us ';
'tsabry@houston.sns.slb.com ';
'dan_schaw@yahoo.com '
Cc: 'ccielab@groupstudy.com '
Subject: RE: OSPF - IGRP and /23?
I believe the only way to get a mask that is smaller than the IGRP/RIP
domain to be advertised is to use a tunnel. So if you had
172.168.1.0/23 on
the OSPF side, and 172.168.12.0/24 on the IGRP side, create a tunnel
between
the two routers in the same classful network with the mask of the
network
you want to be advertised, let's say 172.168.253.0/23. Place this
network
into IGRP, and you should see the 172.168.1.0/23 get advertised to the
IGRP
router. This is because once the IGRP router has a /23 that is directly
connected, it is eligible to receive routes with this subnet mask in the
same classful network. You could also use the loopback or secondary
address
method I guess, but that would put them into the IGRP router as 2 /24's,
not
a /23.
-----Original Message-----
From: kym blair
To: DHSTS68@dhs.state.il.us; tsabry@houston.sns.slb.com;
dan_schaw@yahoo.com
Cc: ccielab@groupstudy.com
Sent: 4/16/2002 5:25 PM
Subject: RE: OSPF - IGRP and /23?
Dan,
Awesome step-by-step explanation. Thanks. Now, how about if you have a
/23
coming from OSPF that you want to get into RIP/IGRP? How do you do
that?
Thanks,
Kym
>From: "DAN DORTON" <DHSTS68@dhs.state.il.us>
>Reply-To: "DAN DORTON" <DHSTS68@dhs.state.il.us>
>To: <tsabry@houston.sns.slb.com>, <dan_schaw@yahoo.com>
>CC: <ccielab@groupstudy.com>
>Subject: RE: OSPF - IGRP
>Date: Tue, 16 Apr 2002 11:01:40 -0500
>
>Let say you have a range of 172.168.1.0/28 in ospf that you need to get
>into a 172.168.2.0/24 IGRP, or RIP domain.
>
>Summary-address only works INTO ospf right?
>
>You need to make this 172.168.1.0/28 network into a 172.168.1.0/24
network
>to overcome the rip/igrp domains classful boundry problems right?
>
>Create a loopback with address 172.168.1.17/28 at your ASBR.
>Do not advertise this network into OSPF.
>Instead create a route-map to permit it.
>
>access-list 1 permit 172.168.1.16 0.0.0.15
>
>route-map con2ospf permit 10
>match ip address 1
>
>Then create a summary address under ospf.
>
>router ospf 1
>summary-address 172.168.1.0 255.255.255.0
>
>Then redistribute connected INTO ospf with the route-map.
>
>router ospf 1
>redistribute connected subnets route-map con2ospf
>
>Since 172.168.1.16/28 network fits into the summary-address range of
>172.168.1.0/24 ospf will create a route to null 0 for the
172.168.1.0/24
>network.
>
>Because connecteds being redistributed INTO ospf are external networks
the
>summary-address works.
>
>Because 172.168.1.0/28 & 172.168.1.16/28 both fit into the major
network
>172.168.1.0/24 the summary-address will work to reach both networks.
>
>Because 172.168.1.0/24 route matches the 172.168.2.0/24 network on the
>igrp/rip domain at the classfull 172.168.0.0/16 & the mask of /24 which
is
>on the igrp/rip domain the igrp/rip domain will accept the summary
route.
>
>Hope this helps everyone.
>
>Dan
>
> >>> Tarek Sabry <tsabry@houston.sns.slb.com> 04/16/02 10:10AM >>>
>Muhammad
>
>Thanks for your reply.
>
>I fully agree that summary-address is for injecting a summary INTO OSPF
and
>not to redistribute into another protocol. But I've seen people using
it
>otherwise :( Is this IOS-related?
>
>How can I create area-range when the router I'm trying to redistribute
at
>is
>not an ABR? I only have area-1 and IGRP on this router.
>
>Creating statics is also prohibited in the lab. Right?
>
>Thanks again
>Tarek
>
>-----Original Message-----
>From: Muhamamd Durrani [mailto:dan_schaw@yahoo.com]
>Sent: Tuesday, April 16, 2002 8:56 AM
>To: Tarek Sabry
>Cc: ccielab@groupstudy.com
>Subject: Re: OSPF - IGRP
>
>
>Hi Tarek ,
>
>With Summary-Address you cannot re-distribute to other
>routing protocol . Its for the Summary Address for
>Ecternal Routes .
>
>I would rather say create a Summary Address with "Area
>range " commad on the router you want to summarized
>the addresses on, with the mask configured on the
>interfaces running IGRP. If the mask is now same as
>configured on IGRP interfaces than you wil not see the
>route on IGRP router .
>
>Another way that I could see is to create a static
>route on ASBR to NULL 0 and redistribute static into
>IGRP process ..but again the mask SHOULD match with
>interaces configured with IGRP .
>
>
>Let me know id I am wrong .
>
>Regards,
>Muhammad
>
>
>--- Tarek Sabry <tsabry@houston.sns.slb.com> wrote:
> > Hi
> >
> > I understand that there may be more than one way to
> > redistribute VLSM into
> > FLSM. However the only way that seems to work for me
> > when redistributing
> > OSPF into IGRP is the brilliant method suggested by
> > someone a little while
> > back, whereby I need to create an intermediate OSPF
> > process. I don't feel
> > comfortable with just this way though, because the
> > proctors may object to
> > it.
> >
> > So let's say we have a /26 network connected to the
> > OSPF side of the
> > redistributing router. Someone had suggested before
> > that a good way of
> > achieveing what I want would be to redistribute
> > connected into OSPF and
> > create a "summary-address" of a /24, and this route
> > would be redistributed
> > into IGRP with the rest of the OSPF routes.
> >
> > Is that supposed to work??? Well doesn't the
> > "summary-address" inject a
> > route INTO OSPF and not OUT OF it?? Also how come I
> > do not see any routes to
> > "Null 0" after I create my OSPF summary address?
> >
> > What are common gotchas for OSPF summaries??
> >
> > Thanks a lot
> > Tarek
> >
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:58:11 GMT-3