From: Alexander Arsenyev (GU/ETL) (alexander.arsenyev@ericsson.com)
Date: Fri Apr 23 2004 - 14:00:13 GMT-3
Hello,
How about this:
1. I read the requirement as follows - we have a block of addresses on R1 (for example 1.1.1.0/24)
which needs to be advertised into OSPF area 0. None of R1's interfaces are in area 0, virtual links
are forbidden, adding new addresses is forbidden.
2. Now the solution - we split our block in 2: 1.1.1.128/25 and 1.1.1.0/25, then add a new Lo1 interface
in R1, give it an IP address 1.1.1.129/25, put it into area 0, create Tunnel interface and unnumber it
to Lo1.
3. Then create Tunnel interface on R3 and unnumber it to any other interface already in area 0.
4. Final part - summarize on R1 so that whole block 1.1.1.0/24 is advertised to area0.
Sample config:
R1:
Interface Lo0
ip add 1.1.1.1 255.255.255.128
ip ospf netw point-to-point
Interface Lo1
ip add 1.1.1.129 255.255.255.128
ip ospf network point-to-point
Interface Tunnel0
ip unnumbered Lo1
tun source <R1' interface>
tun dest <R3' interface>
router ospf 1
netw 1.1.1.128 0.0.0.127 area 0
netw 1.1.1.0 0.0.0.127 area 3
area 3 range 1.1.1.0 255.255.255.0
Comments please?
HTH,
Cheers
Alexander
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
OzgurG@garanti.com.tr
Sent: 23 April 2004 17:32
To: KWygand@customonline.com
Cc: ccielab@groupstudy.com
Subject: RE: OSPF ON GRE Tunnel
including lo0 of R1 in another ospf process as area 2 and redistributing this
new process to the one we already have, should work here... an ugly solution
though
________________________________
From: nobody@groupstudy.com on behalf of Kenneth Wygand
Sent: Fri 4/23/2004 7:15 PM
To: Ashok Verma (ashoverm); Brian McGahan
Cc: ccielab@groupstudy.com
Subject: RE: OSPF ON GRE Tunnel
Did anyone determine how to complete this with a GRE tunnel?
(lo0=area2)R1--(area1)--R2--(area0)--R3
I understand if you can't use a virtual-interface, you must create a GRE
tunnel between R1 and R2. I also understand that the IP address of the
tunnel needs on both sides needs to be in area 0, so the tunnel
interface must be included under the OSPF process.
However, as stated by Ashok, if you are not allowed to create any
additional IP addresses to accomplish this task, the IP addresses of the
tunnel interfaces must be unnumbered to an interface that can be placed
in Area 0. On R3, I know interface to unnumber the tunnel interface can
be selected from any of the p2p interfaces already in Area 0.
But on R1, none of the interfaces are already in Area 0. Now I guess I
could select an interface that is not in _any_ OSPF area and unnumber
the tunnel interface to that and then add the network command under OSPF
to make the tunnel interface part of area 0, but by doing that I'd also
be adding the other interface under area 0. I don't believe there is a
way of getting this out of the OSPF database once its put in under a
network command since OSPF is a LSP.
So I guess my question is this: Is there any other way to accomplish
this task other than what I mentioned above? Keep in mind Ashok's
original requirement was that no new IP addresses could be created for
this task.
Ashok - was this part of a practice labs? If so, which one?
Kenneth E. Wygand
Systems Engineer, Project Services
CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
Network+, A+
Custom Computer Specialists, Inc.
"The only unattainable goal is the one not attempted."
-Anonymous
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Ashok Verma (ashoverm)
Sent: Sunday, March 28, 2004 11:37 PM
To: 'Brian McGahan'
Cc: ccielab@groupstudy.com
Subject: RE: OSPF ON GRE Tunnel
HI Brian,
I understand the solution very well .....that whenever we need to make
the tunnel and need to use ip unnumbered , we need to put the network of
Unnumberd interface in area 0.
If you look at my scenario here ,
>
> R1--------R2-----R3
>
> Between R2 and R3 ospf area 0 is running, and between R1 and R2 area
3.
On R1 I have a loopback address ( 1.1.1.1) and my requirement is to
> put it in area 1. And I should not be using the virtual link. I should
> have 1.1.1.1 in R3's routing table.Is any way to do it .
>
We need to make a tunnel between the R2 and R1. On R2 the requirement of
putting tunnel Unnumberd interface in area 0 is not a problem since R2
has a interface( Connected to R3) already in area 0.
But on R1 there is only one interface which is connected R2 using area
3, So I don't have any interface to put in area 0 .what should I do in
this case ....
Thanks and Regards,
Ashok
>
>
>
> "Ashok Verma (ashoverm)" <ashoverm@cisco.com> wrote:
> Hi all
>
> For all OSPF gurus.....here is a very good query....
>
> R1--------R2-----R3
>
> Between R2 and R3 ospf area 0 is running, and between R1 and R2 area
> 3,
>
> On R1 I have a loopback address ( 1.1.1.1) and my requirement is to
> put it in area 1. And I should not be using the virtual link. I should
> have 1.1.1.1 in R3's routing table.Is any way to do it .
>
> As per my views, there are two ways .....
>
> Solution 1: Use Tunnel between R2 and R1 and then assign the tunnel IP
> in ospf area 0 ...........But the question is In real lab we are not
> allowed to use any extra ip....so can we still use this solution using
> the IP unnumberd.( in that case what ip we should be putting in area 0
> ??)
>
> Solution 2: Use multiple process on R1 and then redistribute them .But
> again question is are we allowed to use multiple process ids in ospf.
>
> Which solution look better from the real lab point of view.
>
>
> Regards.
>
> Ashok Kumar Verma
> CCIP,CCDP,CCNP
> Network Consulting Engineer
> Customer Advocacy Advanced Service Dep.
> Service Provider AS Div.2
> Cisco Systems, K.K.Japan.
>
> Tel: +81-3-5324-4583
> e-mail: ashoverm@cisco.com
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