RE: Unnumbered and Virtual Links

Hi Marko,
R4 (4.4.4.4/32) and R5 (5.5.5.5/32) are not on common subnet on interface . I am wondering how is neighbor ship coming up between.

Thanks,
Sonu
-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Marko Milivojevic
Sent: Thursday, July 15, 2010 11:51 PM
To: Yaseen Mirza
Cc: ccielab_at_groupstudy.com
Subject: Re: Unnumbered and Virtual Links

There is nothing stopping you from running virtual link with
unnembered serial interfaces in the transit area. You can look-up if
your virtual link works by using "show ip ospf neighbor" command.

When in doubt... lab it up.

R2---{area 0}---R4---{area 45, unnumbered}---R5---{area 0}---R6

! ------------------------------8<------------------------------
! R2:
! --------------------------------------------------------------
interface Loopback0
 ip address 2.2.2.2 255.255.255.255
!
interface Serial0/1/0
 no ip address
 encapsulation frame-relay
 no frame-relay inverse-arp
!
interface Serial0/1/0.204 point-to-point
 ip address 24.24.24.2 255.255.255.0
 frame-relay interface-dlci 204
!
router ospf 1
 router-id 2.2.2.2
 log-adjacency-changes
 network 2.2.2.2 0.0.0.0 area 0
 network 24.24.24.2 0.0.0.0 area 0
!
! ------------------------------8<------------------------------
! R4:
! --------------------------------------------------------------
interface Loopback0
 ip address 4.4.4.4 255.255.255.255
!
interface Serial0/0/0
 no ip address
 encapsulation frame-relay
 no frame-relay inverse-arp
!
interface Serial0/0/0.402 point-to-point
 ip address 24.24.24.4 255.255.255.0
 frame-relay interface-dlci 402
!
interface Serial0/1/0
 ip unnumbered Loopback0
!
router ospf 1
 router-id 4.4.4.4
 log-adjacency-changes
 area 45 virtual-link 5.5.5.5
 network 4.4.4.4 0.0.0.0 area 45
 network 24.24.24.4 0.0.0.0 area 0
!
! ------------------------------8<------------------------------
! R5:
! --------------------------------------------------------------
interface Loopback0
 ip address 5.5.5.5 255.255.255.255
!
interface Serial0/0/0
 ip unnumbered Loopback0
!
interface Serial0/1/0
 no ip address
 encapsulation frame-relay
 no frame-relay inverse-arp
!
interface Serial0/1/0.56 point-to-point
 ip address 56.56.56.5 255.255.255.0
 frame-relay interface-dlci 506
!
router ospf 1
 router-id 5.5.5.5
 log-adjacency-changes
 area 45 virtual-link 4.4.4.4
 network 5.5.5.5 0.0.0.0 area 45
 network 56.56.56.5 0.0.0.0 area 0
!
! ------------------------------8<------------------------------
! R6:
! --------------------------------------------------------------
interface Loopback0
 ip address 6.6.6.6 255.255.255.255
!
interface Serial0/1/0
 no ip address
 encapsulation frame-relay
 no frame-relay inverse-arp
!
interface Serial0/1/0.56 point-to-point
 ip address 56.56.56.6 255.255.255.0
 frame-relay interface-dlci 605
!
router ospf 1
 router-id 6.6.6.6
 log-adjacency-changes
 network 6.6.6.6 0.0.0.0 area 0
 network 56.56.56.6 0.0.0.0 area 0
!
------------------------------8<------------------------------

R2#ping 6.6.6.6 source Loopback 0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:
Packet sent with a source address of 2.2.2.2
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 24/27/28 ms

R4#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
5.5.5.5 0 FULL/ - - 5.5.5.5 OSPF_VL0
2.2.2.2 0 FULL/ - 00:00:31 24.24.24.2
Serial0/0/0.402
5.5.5.5 0 FULL/ - 00:00:34 5.5.5.5 Serial0/1/0

R5#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
4.4.4.4 0 FULL/ - - 4.4.4.4 OSPF_VL0
6.6.6.6 0 FULL/ - 00:00:33 56.56.56.6 Serial0/1/0.56
4.4.4.4 0 FULL/ - 00:00:34 4.4.4.4 Serial0/0/0

R6#ping 2.2.2.2 source Loopback0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
Packet sent with a source address of 6.6.6.6
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 24/27/28 ms

--
Marko Milivojevic - CCIE #18427
Senior Technical Instructor - IPexpert
YES! We include 400 hours of REAL rack
time with our Blended Learning Solution!
Mailto: markom_at_ipexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Web: http://www.ipexpert.com/
On Thu, Jul 15, 2010 at 13:43, Yaseen Mirza <yaseengs_at_gmail.com> wrote:
> Hi
>
> I have been trying to run a virtual-link whilst having an unnumbered serial
> link in the transit area for the VL.
> Having read about this in more detail I have found that this is not actually
> possible.
> Can somebody please confirm this? Is there any way round this?
>
> Also I am in some doubt about standard virtual links. When I create a
> virtual-link, it is created on the router-id.
> How do we find out where the VL neighbor actually exists. e.g.
>
> area 1 virtual-link 1.1.1.1
>
> If I look in the ospf database it shows me that 1.1.1.1 is known by
> advertising router 1.1.1.1
> So how do I find out where 1.1.1.1 is from the ospf database?
Blogs and organic groups at http://www.ccie.net