Solved: Re: OSPF Vitual Link Issue

libra_ali786 · ‎12-03-2018

My Topology.

Before creating OSPF Virtual Link between R1&R2 , routing table getting inter area route (circle with red color). I understood with no doubt. The table belong to R2 Router.

But, After creating OSPF Virtual Link between R1&R2 , routing table getting intra area route (circle with red color). Why it change Inter area route into Intra route? I think so it should be inter area route instead Intra area ?

Note : The table belong to R2 Router.

paul driver · ‎12-03-2018

Hello

@libra_ali786 wrote:but why OSPF VL change Inter to Intra? is because of VL?

YES

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

View solution in original post

Georg Pauwen · ‎12-03-2018

Hello,

how did you configure the VL ? Post the full configs of R1 and R2...

libra_ali786 · ‎12-03-2018

R1#show run | sec ospf
router ospf 1
area 1 virtual-link 192.168.23.2
network 1.1.1.0 0.0.0.255 area 0
network 30.30.30.0 0.0.0.255 area 1
network 192.168.12.0 0.0.0.255 area 1

R2#show run | sec osp
router ospf 1
area 1 virtual-link 30.30.30.1
network 192.168.12.0 0.0.0.255 area 1
network 192.168.23.0 0.0.0.255 area 2

Georg Pauwen · ‎12-03-2018

Hello,

the VL config does not look right. In your case, area 1 is the transit area, so all interfaces should be in area 1. R3 is the other end of the virtual link, so R1 needs to establish the VL with R3, and vice versa. So your configs should look something like the below (I used loopbacks to establish the virtual link):

R1#show run | sec ospf
router ospf 1
area 1 virtual-link 3.3.3.3
network 1.1.1.1 0.0.0.0 area 0
network 192.168.12.0 0.0.0.255 area 1

R2#show run | sec osp
router ospf 1
network 192.168.12.0 0.0.0.255 area 1
network 192.168.23.0 0.0.0.255 area 1

R3#show run | sec osp
router ospf 1

area 1 virtual-link 1.1.1.1
network 3.3.3.3 0.0.0.0 area 2
network 192.168.23.0 0.0.0.255 area 1

paul driver · ‎12-03-2018

Hello

@libra_ali786 wrote:

That because router 2 is now connected to the BB router 1 via the VL in area 0 thus an intra-area route.

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

libra_ali786 · ‎12-03-2018

As per OSPF multi-area scenario we always get an Inter area routes between different area pass by BB. am i right?

but why OSPF VL change Inter to Intra? is because of VL?

Georg Pauwen · ‎12-03-2018

Hello,

do you actually get the Virtual Link working with your config ? Can you post the output of 'show ip ospf virtual-link' from both sides of the link ?

libra_ali786 · ‎12-03-2018

Yes.

R1#show ip ospf v
Virtual Link OSPF_VL0 to router 192.168.23.2 is up
Run as demand circuit
DoNotAge LSA allowed.
Transit area 1, via interface FastEthernet0/0
Topology-MTID    Cost    Disabled     Shutdown      Topology Name
        0           1         no          no            Base
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:08
    Adjacency State FULL (Hello suppressed)
    Index 1/2, retransmission queue length 0, number of retransmission 0
    First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
    Last retransmission scan length is 0, maximum is 0
    Last retransmission scan time is 0 msec, maximum is 0 msec

R2#show ip os v
Virtual Link OSPF_VL0 to router 30.30.30.1 is up
Run as demand circuit
DoNotAge LSA allowed.
Transit area 1, via interface FastEthernet2/0
Topology-MTID    Cost    Disabled     Shutdown      Topology Name
        0           1         no          no            Base
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:07
    Adjacency State FULL (Hello suppressed)
    Index 1/3, retransmission queue length 0, number of retransmission 0
    First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
    Last retransmission scan length is 0, maximum is 0
    Last retransmission scan time is 0 msec, maximum is 0 msec

Georg Pauwen · ‎12-03-2018

Hello,

post the full configs of all three routers, not just snippets. I cannot recreate your setup in GNS3, I get an error about a backbone area mismatch...

libra_ali786 · ‎12-03-2018

R1#show running-config
Building configuration...

Current configuration : 1155 bytes
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
no ip icmp rate-limit unreachable
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
!
multilink bundle-name authenticated
!
!
ip tcp synwait-time 5
!
interface Loopback1
ip address 1.1.1.1 255.255.255.0
!
interface Loopback99
ip address 30.30.30.1 255.255.255.0
!
interface FastEthernet0/0
ip address 192.168.12.1 255.255.255.0
duplex full
!
interface FastEthernet2/0
no ip address
shutdown
speed auto
duplex auto
!
interface FastEthernet2/1
no ip address
shutdown
speed auto
duplex auto
!
router ospf 1
area 1 virtual-link 192.168.23.2
network 1.1.1.0 0.0.0.255 area 0
network 30.30.30.0 0.0.0.255 area 1
network 192.168.12.0 0.0.0.255 area 1
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line vty 0 4
login
!
!
end

R2#show running-config
Building configuration...

Current configuration : 1019 bytes
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
!
hostname R2
!
boot-start-marker
boot-end-marker
!
no aaa new-model
no ip icmp rate-limit unreachable
!
no ip domain lookup
ip cef
no ipv6 cef
!
!
multilink bundle-name authenticated
!
!
ip tcp synwait-time 5
!
!
interface FastEthernet0/0
no ip address
shutdown
duplex full
!
interface FastEthernet2/0
ip address 192.168.12.2 255.255.255.0
speed auto
duplex auto
!
interface FastEthernet2/1
ip address 192.168.23.2 255.255.255.0
speed auto
duplex auto
!
router ospf 1
area 1 virtual-link 30.30.30.1
network 192.168.12.0 0.0.0.255 area 1
network 192.168.23.0 0.0.0.255 area 2
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line vty 0 4
login
!
!
end

R3#show running-config
Building configuration...

Current configuration : 1030 bytes
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
!
hostname R3
!
boot-start-marker
boot-end-marker
!
no aaa new-model
no ip icmp rate-limit unreachable
!
no ip domain lookup
ip cef
no ipv6 cef
!
!
multilink bundle-name authenticated
!
ip tcp synwait-time 5
!
interface Loopback1
ip address 10.10.10.1 255.255.255.0
!
interface FastEthernet0/0
ip address 192.168.23.3 255.255.255.0
duplex full
!
interface FastEthernet2/0
no ip address
shutdown
speed auto
duplex auto
!
interface FastEthernet2/1
no ip address
shutdown
speed auto
duplex auto
!
router ospf 1
network 10.10.10.0 0.0.0.255 area 2
network 192.168.23.0 0.0.0.255 area 2
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line vty 0 4
login
!
!
end

Georg Pauwen · ‎12-03-2018

Hello,

the main reason your VL is misconfigured is the lines marked in bold. You are trying to establish the VL using area 1 as transit area, and with the other side, 30.30.30.1 also being in area 1. The VL might be up but it isn't working. You need to link to something in the backbone area, area 0. That is the whole idea of a virtual link.

R1

router ospf 1
area 1 virtual-link 192.168.23.2
network 1.1.1.0 0.0.0.255 area 0
network 30.30.30.0 0.0.0.255 area 1
network 192.168.12.0 0.0.0.255 area 1

R2

router ospf 1
area 1 virtual-link 30.30.30.1
network 192.168.12.0 0.0.0.255 area 1
network 192.168.23.0 0.0.0.255 area 2

Have a look at the document below, it has a fairly simple sample setup involving three routers:

https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/47866-ospfdb7.html

libra_ali786 · ‎12-03-2018

My 30.30.30.0 network is a loopback inerface. Thats why it does not matter "network 30.30.30.0 0.0.0.255 area 1" because router ID always highest loopback IP.

But in other hand i put network 30.30.30.0 0.0.0.255 area 0 , but result was same. I mentiond in Bold.

R2#
Gateway of last resort is not set

      1.0.0.0/32 is subnetted, 1 subnets
O        1.1.1.1 [110/2] via 192.168.12.1, 00:20:34, FastEthernet2/0
      10.0.0.0/32 is subnetted, 1 subnets
O        10.10.10.1 [110/2] via 192.168.23.3, 00:20:54, FastEthernet2/1
      30.0.0.0/32 is subnetted, 1 subnets
O        30.30.30.1 [110/2] via 192.168.12.1, 00:02:27, FastEthernet2/0
      192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C        192.168.12.0/24 is directly connected, FastEthernet2/0
L        192.168.12.2/32 is directly connected, FastEthernet2/0
      192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C        192.168.23.0/24 is directly connected, FastEthernet2/1
L        192.168.23.2/32 is directly connected, FastEthernet2/1

paul driver · ‎12-03-2018

Hello

@libra_ali786 wrote:but why OSPF VL change Inter to Intra? is because of VL?

YES

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

libra_ali786 · ‎12-04-2018

Thanks Paul driver. i accept your solution. but i nedd some more techinal detial which i got.