From: Schulz, Dave (DSchulz@dpsciences.com)
Date: Wed Nov 09 2005 - 16:42:48 GMT-3
Ah! I get it now. Therefore, the key is with tunnels in OSPF is that
both ends must be in the same area (or, of the interfaces that they
represent ....loopback0, in this case).... Even if you are using
unnumbered. Thanks for the great explanation, Brian!
Dave Schulz
Email: dschulz@dpsciences.com
-----Original Message-----
From: Brian Dennis [mailto:bdennis@internetworkexpert.com]
Sent: Wednesday, November 09, 2005 2:34 PM
To: Schulz, Dave
Cc: Cisco certification
Subject: RE: OSPF Area 0 Tuneling
Dave,
One thing to remember about using unnumbered interfaces is that
interfaces on both sides of the link must be in the same area. See
below:
hostname Rack8R1
!
interface Loopback0
ip address 150.8.1.1 255.255.255.0
!
interface Tunnel0
ip unnumbered Loopback0
tunnel source 129.8.124.1
tunnel destination 129.8.124.2
!
interface Serial0/0
ip address 129.8.124.1 255.255.255.0
encapsulation frame-relay
frame-relay map ip 129.8.124.2 102 broadcast
no frame-relay inverse-arp
!
router ospf 1
network 150.8.0.0 0.0.255.255 area 0
!
end
Rack8R1#sho ip os n
Neighbor ID Pri State Dead Time Address
Interface
150.8.2.2 0 FULL/ - 00:00:33 150.8.2.2
Tunnel0
Rack8R1#
hostname Rack8R2
!
interface Loopback0
ip address 150.8.2.2 255.255.255.0
!
interface Tunnel0
ip unnumbered Loopback0
tunnel source 129.8.124.2
tunnel destination 129.8.124.1
!
interface Serial0/0
ip address 129.8.124.2 255.255.255.0
encapsulation frame-relay
frame-relay map ip 129.8.124.1 201 broadcast
no frame-relay inverse-arp
!
router ospf 1
network 150.8.0.0 0.0.255.255 area 0
!
end
Rack8R2#sho ip os n
Neighbor ID Pri State Dead Time Address
Interface
150.8.1.1 0 FULL/ - 00:00:32 150.8.1.1
Tunnel0
Rack8R2#
Now if we change the area on R2's loopback to area 1 from area 0 they
won't be able to become neighbors since the interfaces they are using
for unnumbered (Lo0) are not in the same area:
Rack8R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Rack8R2(config)#router ospf 1
Rack8R2(config-router)#no network 150.8.0.0 0.0.255.255 area 0
%OSPF-5-ADJCHG: Process 1, Nbr 150.8.1.1 on Tunnel0 from FULL to DOWN,
Neighbor Down: Interface down or detached
Rack8R2(config-router)# network 150.8.0.0 0.0.255.255 area 1
Rack8R2(config-router)#^Z
Rack8R2#
%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone
area must be virtual-link but not found from 150.8.1.1, Tunnel0
Rack8R2#
%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone
area must be virtual-link but not found from 150.8.1.1, Tunnel0
Rack8R2#
HTH,
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Schulz, Dave
Sent: Wednesday, November 09, 2005 6:54 AM
To: Chris Lewis; De Witt, Duane; Dave Temkin; Dan Agache
Cc: Cisco certification
Subject: RE: OSPF Area 0 Tuneling
Ah! That first statement explains the way the router is thinking in
this case! Thanks, Chris.
Dave Schulz
Email: dschulz@dpsciences.com <mailto:dschulz@dpsciences.com%20>
________________________________
From: Chris Lewis [mailto:chrlewiscsco@yahoo.com]
Sent: Wednesday, November 09, 2005 9:39 AM
To: Schulz, Dave; De Witt, Duane; Dave Temkin; Dan Agache
Cc: Cisco certification
Subject: RE: OSPF Area 0 Tuneling
OSPF performs subnet number and mask checks on all media except point to
point and virtual lilnks (RFC2328 section 10.5).
If one was crazy enough to change the interface to a broadcast network
type, the neighbor relationship would not be able to form.
Chris
"Schulz, Dave" <DSchulz@dpsciences.com> wrote:
Interesting! Trying to think like the router on this one, can
someone
explain how this would possible be acceptable? Doesn't the
tunnel look
like a circuit to this scenario? Doesn't it have to be on the
same
subnet?
Dave Schulz,
Email: dschulz@dpsciences.com
-----Original Message-----
From: De Witt, Duane [mailto:duane.dewitt@siemens.com]
Sent: Wednesday, November 09, 2005 9:04 AM
To: Schulz, Dave; Dave Temkin; Dan Agache
Cc: Cisco certification
Subject: RE: OSPF Area 0 Tuneling
Well, according to the IE solution you can. (150.1.3.3/24 and
150.1.4.4/24 on the endpoints of the tunnel) I haven't labbed it
yet,
I'll quickly change my tunnels to match their solution and see
how it
works.
-----Original Message-----
From: Schulz, Dave [mailto:DSchulz@dpsciences.com]
Sent: 09 November 2005 03:57 PM
To: Dave Temkin; Dan Agache
Cc: De Witt, Duane; Cisco certification
Subject: RE: OSPF Area 0 Tuneling
This brings up a question....Since the tunnel is specifically
being used
to extend area 0, and the tunnel must have both ends in the same
subnet.
Doesn't this tunnel have to be an assigned ip address that is on
the
same subnet (both ends of the tunnel)? And, this subnet would
then have
to be assigned to area 0. Can this even be done with ip
unnumbered?
Dave Schulz,
Email: dschulz@dpsciences.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
Behalf Of
Dave Temkin
Sent: Wednesday, November 09, 2005 8:15 AM
To: Dan Agache
Cc: De Witt, Duane; Cisco certification
Subject: Re: OSPF Area 0 Tuneling
Be sure to read the wording of the lab carefully. They may (or
may not)
allow you to create additional IP addressing within a certain
scope, as
needed.
Using ip unnumbered to a loopback isn't all that great of an
idea, as
your
loopbacks will generally be in different subnets.
-Dave
On Wed, 9 Nov 2005, Dan Agache wrote:
> I think that you have to use all that the lab is given,
nothing more.
Using another subnet address is extra commands and is not a good
idea.
That's my opinion.
>
>
> "De Witt, Duane" wrote:
> Hi Group
>
>
>
> Quick question: in the lab if you have to join discontiguous
area 0's
> with tunnels is it better to use ip unnumbered loopback 0
(assuming
> loopback 0 is in area 0) or a new IP address and add the new
subnet to
> area 0 as well as the loopback.
>
>
>
> I'm asking this because in IEWB V2 Lab3, area 0 consists of
the
loopback
> interface of each router. So a tunnel was used using ip
unnumbered
> loopback 0. My solution was to create a new subnet for the
tunnel and
> add it to area 0.
>
>
>
> Regards
>
> Duane
>
>
>
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