OSPF tunnel issue

Guys

I am facing a strange issue with below topology:

(R1 s0/0)------AREA 0 ------------s0/0 (R2 F0/1)----------------AREA 1-----------(F0/1 R3)-----------AREA 2----------- (R4)
                192.168.12.0/24                                           192.168.24.0/24 


As you can see that R4 is not connected to backbone router therefore it is require virtual link or tunnel.
for this configuration , I used tunnel to configure between R2 and R3

Below is the config :-

R2 -

interface Tunnel0
 ip address 22.22.22.22 255.255.255.0
 ip ospf network broadcast
 tunnel source 192.168.23.2
 tunnel destination 192.168.23.3
end


R3

interface Tunnel0
 ip address 33.33.33.33 255.255.255.0
 ip ospf network broadcast
 tunnel source 192.168.23.3
 tunnel destination 192.168.23.2
end

The 22.22.22.22 and 33.33.33.33 has been advertise into (tunnel IP) AREA 0 :


R2#sh run | sec router ospf
router ospf 1
 router-id 2.2.2.2
 log-adjacency-changes
 network 2.2.2.2 0.0.0.0 area 1
 network 22.22.22.22 0.0.0.0 area 0
 network 192.168.12.2 0.0.0.0 area 0
 network 192.168.23.2 0.0.0.0 area 1


Now the issue is that , I am able to ping 22.22.22.22 address from router R3 but not able to do ping 33.33.33.33
from R2 , The tunnel is up both end side.

if I check the ospf database on R2 for network 33.33.33.0/24 , you can see that it is there in database but
not in routing table as ROUTING BIT IS NOT SET

R2#show ip ospf database sum 33.33.33.0

            OSPF Router with ID (2.2.2.2) (Process ID 1)

                Summary Net Link States (Area 1)

  LS age: 48
  Options: (No TOS-capability, DC, Upward)
  LS Type: Summary Links(Network)
  Link State ID: 33.33.33.0 (summary Network Number)
  Advertising Router: 3.3.3.3
  LS Seq Number: 80000005
  Checksum: 0xD2A
  Length: 28
  Network Mask: /24
        TOS: 0  Metric: 11111

        TOS: 0  Metric: 11111


if you do same command on R3 for network 22.22.22.0 then :-


R3#show ip ospf database sum 22.22.22.0

            OSPF Router with ID (3.3.3.3) (Process ID 1)

                Summary Net Link States (Area 1)

  Routing Bit Set on this LSA  <----  NOTE
  LS age: 1471
  Options: (No TOS-capability, DC, Upward)
  LS Type: Summary Links(Network)
  Link State ID: 22.22.22.0 (summary Network Number)
  Advertising Router: 2.2.2.2
  LS Seq Number: 80000007
  Checksum: 0xB4A5
  Length: 28
  Network Mask: /24
        TOS: 0  Metric: 11111

You can see that routing bit set for 22.22.22.0 on R3 and it is there in routing table. I can ping this network

Ping Test :-

R2#ping 33.33.33.33

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 33.33.33.33, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R2#
R2#
R2#show ip route 33.33.33.33
% Network not in table

R3#ping 22.22.22.22

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 22.22.22.22, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/40/80 ms
R3#
R3#show ip route 22.22.22.22
Routing entry for 22.22.22.0/24
  Known via "ospf 1", distance 110, metric 11112, type inter area
  Last update from 192.168.23.2 on FastEthernet1/0, 00:17:55 ago
  Routing Descriptor Blocks:
  * 192.168.23.2, from 2.2.2.2, 00:17:55 ago, via FastEthernet1/0
    Route metric is 11112, traffic share count is 1

The another thing is that if I shutdown serial interface S0/0 of R2 then I am able to ping 33.33.33.33 network , The S0/0 is touch to backbone area (area 0)

R2#config t
Enter configuration commands, one per line.  End with CNTL/Z.
R2(config)#int s0/0
R2(config-if)#shut
R2(config-if)#
*Mar  1 02:09:46.111: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on Serial0/0 from F
ULL to DOWN, Neighbor Down: Interface down or detached
*Mar  1 02:09:48.095: %LINK-5-CHANGED: Interface Serial0/0, changed state to adm
inistratively down
*Mar  1 02:09:49.095: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0,
 changed state to down
R2(config-if)#
R2(config-if)#
R2(config-if)#
R2(config-if)#end
R2#
R2#
R2#ping 33.33.33.33

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 33.33.33.33, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/36/116 ms
R2#
R2#
R2#show ip ospf database sum 33.33.33.0

            OSPF Router with ID (2.2.2.2) (Process ID 1)

                Summary Net Link States (Area 1)

  Routing Bit Set on this LSA  (<--- Now routing bit set)
  LS age: 1980
  Options: (No TOS-capability, DC, Upward)
  LS Type: Summary Links(Network)
  Link State ID: 33.33.33.0 (summary Network Number)
  Advertising Router: 3.3.3.3
  LS Seq Number: 80000004
  Checksum: 0xF29
  Length: 28
  Network Mask: /24
        TOS: 0  Metric: 11111

 

Can anyone know what is the issue with this config?

Regards

Amit Chopra

Comments

  • why do you have the tunnel interface ip addresses on different networks?

    if you do it like this, it should work:

     

    R2


    interface Tunnel0

     ip address 23.0.0.2 255.255.255.0

     tunnel source 192.168.23.2

     tunnel destination 192.168.23.3

    router ospf 1

    net 23.0.0.2 0.0.0.0 area 0

     


    R3

     

    interface Tunnel0

     ip address 23.0.0.3 255.255.255.0

     tunnel source 192.168.23.3

     tunnel destination 192.168.23.2

    router ospf 1

    net 23.0.0.3 0.0.0.0 area 0

     

     

    and you shouldn't have to change the tunnel interface ospf network type.  if you leave that alone, it defaults to point-to-point which works fine.  but maybe I'm missing something with what you were after.

  • Did you add a network statement for the tunnel network to the OSPF process on router 3 (you only show it for R2), and is there an OSPF adjacency across the GRE tunnel?  Also, your tunnel src/dst -- are those /32 loopback interface addresses?  And yeah, as nklhd pointed out it's odd to have the tunnel endpoints on different IP subnets...

  • well guys enough reasons to say here " I AM CRAZY .............." :)

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