OSPF Connectivity Issue

Paki · ‎02-20-2017

Hi there

Attached herewith is my OSPF network template (Image 1).

Everything is working very good.

PC-1 can PING PC-2 & OSPF is following best possible costs. When I PING PC-2 to PC-1 (& vice versa), the packet follows path as attached in image 2.

But if I remove the link between R1 (192.168.0.17/30) & R5 (192.168.0.18/30), the ICMP packets from any of these both PC(s) do not travel over any other path. They don't PING any other device except their own gateways & their builtin connected ethernet interfaces.

I also noticed that traffic is not flowing via any Serial link.

OSPF is properly establishing neighbor relationship with next hops.

What could be the possible reason for that?

Your professional advise would be appreciated.

Thank/Regards

Satwant Singh · ‎02-20-2017

Kindly give the output of R1, R2, R3 & R4 show ip route ospf

Paki · ‎02-20-2017

Dear Satwant Singh Dhaliwal !!!

Please find attached outputs of "show ip route ospf" for R1, R2, R3, R4.

I am thankful for your quick response to solve my problem.

Julio E. Moisa · ‎02-20-2017

Hi,

Could you please execute this command on R1, R2, R3 and R4 and share the outputs. I would like to be sure the adjacency and if they are connected properly.

show ip ospf neighbors

>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<

Paki · ‎02-20-2017

Dear Julio Moisa !!!

Attached is the file as output of "show ip ospf neighbor" on R1, R2, R3, R4 & R5.

Also please elaborate dead timers.

Thank You

Satwant Singh · ‎02-20-2017

Dear Yawar Aziz,

But if I remove the link between R1 (192.168.0.17/30) & R5 (192.168.0.18/30), the ICMP packets from any of these both PC(s) do not travel over any other path

Are you sure that you removed the link between r1 and r5 ? .... but its still showing connected in these outputs:

R1#show ip route ospf 
O    10.0.0.0 [110/3] via 192.168.0.18, 00:00:07, FastEthernet0/0

R1#show ip ospf neighbor 

Neighbor ID     Pri   State           Dead Time   Address         Interface
192.168.0.30      1   FULL/DR         00:00:31    192.168.0.18    FastEthernet0/0

Paki · ‎02-20-2017

Dear Satwant Singh Dhaliwal !!!

Please see attachment show results of "show ip route ospf" & "show ip ospf neighbor" alongwith a link detached error message from OSPF.

Thank you for your responses.

Satwant Singh · ‎02-20-2017

Dear AZIZ,

First of all, remove the link between R1 & R5 and then send me the command output of #show ip route 172.16.20.10 (PC1) and #sh ip route 10.0.0.10 (PC2) all the routers R1 to R5

Secondly, Advertise the 10.0.0.0/8 network correctly with 0.0.0.255 wild card mask.

R3#
router ospf 30
 log-adjacency-changes
 network 192.168.0.24 0.0.0.3 area 0
 network 192.168.0.8 0.0.0.3 area 0
 network 10.0.0.0 0.255.255.255 area 0
 network 192.168.0.20 0.0.0.3 area 0

Paki · ‎02-21-2017

You said, "Secondly, Advertise the 10.0.0.0/8 network correctly with 0.0.0.255 wild card mask." After this, the tracert from PC-1 to PC-2 is as under:

C:\>tracert 10.0.0.10

Tracing route to 10.0.0.10 over a maximum of 30 hops:

1 0 ms 0 ms 0 ms 172.16.20.1

2 0 ms 0 ms 0 ms 192.168.0.2

3 1 ms 0 ms 0 ms 192.168.0.6

4 0 ms 0 ms 0 ms 192.168.0.26

5 0 ms 1 ms 0 ms 10.0.0.10

Trace complete.

Now I executed this command with R1 - R5 link established but this time, the packet traveled from R1, R2, R5 & R4.

What that wildcard change command did with route changed?

Then, As you said, I removed the link between R1-R5 & executed show ip route 172.16.20.10 & show ip route 10.0.0.10 on every router as under:

R1#show ip route 172.16.20.10
Routing entry for 172.16.20.0/24
Known via "connected", distance 0, metric 0 (connected, via interface)
Routing Descriptor Blocks:
* directly connected, via FastEthernet1/0
      Route metric is 0, traffic share count is 1

R1#show ip route 10.0.0.10
Routing entry for 10.0.0.0/8
Known via "ospf 10", distance 110, metric 4, type intra area
Last update from 192.168.0.2 on FastEthernet0/1, 00:14:47 ago
Routing Descriptor Blocks:
* 192.168.0.2, from 192.168.0.26, 00:14:47 ago, via FastEthernet0/1
      Route metric is 4, traffic share count is 1
===============================================================================
R2#show ip route 172.16.20.10
Routing entry for 172.16.20.0/24
Known via "ospf 20", distance 110, metric 2, type intra area
Last update from 192.168.0.1 on FastEthernet0/1, 00:18:24 ago
Routing Descriptor Blocks:
* 192.168.0.1, from 192.168.0.17, 00:18:24 ago, via FastEthernet0/1
      Route metric is 2, traffic share count is 1

R2#show ip route 10.0.0.10
Routing entry for 10.0.0.0/8
Known via "ospf 20", distance 110, metric 3, type intra area
Last update from 192.168.0.6 on FastEthernet1/0, 00:18:36 ago
Routing Descriptor Blocks:
* 192.168.0.6, from 192.168.0.26, 00:18:36 ago, via FastEthernet1/0
      Route metric is 3, traffic share count is 1
================================================================================
R3#show ip route 172.16.20.10
Routing entry for 172.16.20.0/24
Known via "ospf 30", distance 110, metric 4, type intra area
Last update from 192.168.0.25 on FastEthernet0/1, 00:16:31 ago
Routing Descriptor Blocks:
* 192.168.0.25, from 192.168.0.17, 00:16:31 ago, via FastEthernet0/1
      Route metric is 4, traffic share count is 1

R3#show ip route 10.0.0.10
Routing entry for 10.0.0.0/8
Known via "connected", distance 0, metric 0 (connected, via interface)
Routing Descriptor Blocks:
* directly connected, via FastEthernet1/0
      Route metric is 0, traffic share count is 1
====================================================================================
R4#show ip route 172.16.20.10
Routing entry for 172.16.20.0/24
Known via "ospf 40", distance 110, metric 4, type intra area
Last update from 192.168.0.30 on FastEthernet0/1, 00:17:22 ago
Routing Descriptor Blocks:
* 192.168.0.30, from 192.168.0.17, 00:17:22 ago, via FastEthernet0/1
      Route metric is 4, traffic share count is 1

R4#show ip route 10.0.0.10
Routing entry for 10.0.0.0/8
Known via "ospf 40", distance 110, metric 3, type intra area
Last update from 192.168.0.30 on FastEthernet0/1, 00:20:10 ago
Routing Descriptor Blocks:
* 192.168.0.30, from 192.168.0.26, 00:20:10 ago, via FastEthernet0/1
      Route metric is 3, traffic share count is 1
=======================================================================================
R5#show ip route 172.16.20.10
% Network not in table

R5#show ip route 10.0.0.10
% Network not in table

The question arises that even routers are showing connected status of 172.16.20.10 & 10.0.0.10, then why these both PC can not access any interface of R2, R3, R4 & R5 except their immediate connected WAN interfaces. I mean no ICMP packet can get at any router interfaces on any IP.

Dear Sir!!!

I am thankful for your swift replies & for your interest solving my problem.

Satwant Singh · ‎02-21-2017

Dear AZIZ,

Perfect my friend, we are very close. Now the biggest question is that when link is removed between R1 & R5 then why there is no route of PC-1 and PC2 networks (It should not happen, coz R5 have ospf neighbor-ship with R2, R4 and R3 )?

Kindly share the below detail of R5:

1/ Sh run

2/ Sh ip route connected

3/ sh ip route ospf (Both cases)

4/ sh ip int br

5/ sh ip os nei

6/ sh ip os database

Paki · ‎02-21-2017

R5#show run

Building configuration...

Current configuration : 992 bytes

!

version 12.4

no service timestamps log datetime msec

no service timestamps debug datetime msec

no service password-encryption

!

hostname Router

!

no ip cef

no ipv6 cef

!

no ip domain-lookup

!

spanning-tree mode pvst

!

interface FastEthernet0/0

ip address 192.168.0.18 255.255.255.252

duplex auto

speed auto

!

interface FastEthernet0/1

ip address 192.168.0.25 255.255.255.252

duplex auto

speed auto

!

interface Ethernet0/1/0

ip address 192.168.0.30 255.255.255.252

duplex auto

speed auto

!

interface FastEthernet1/0

ip address 192.168.0.6 255.255.255.252

!

interface Vlan1

no ip address

shutdown

!

router ospf 50

log-adjacency-changes

network 192.168.0.28 0.0.0.3 area 0

network 192.168.0.16 0.0.0.3 area 0

network 192.168.0.4 0.0.0.3 area 0

network 192.168.0.24 0.0.0.3 area 0

!

ip classless

!

ip flow-export version 9

!

line con 0

exec-timeout 0 0

logging synchronous

!

line aux 0

!

line vty 0 4

login

!

end

R5#show ip route connected

C 192.168.0.4/30 is directly connected, FastEthernet1/0

C 192.168.0.16/30 is directly connected, FastEthernet0/0

C 192.168.0.24/30 is directly connected, FastEthernet0/1

C 192.168.0.28/30 is directly connected, Ethernet0/1/0

R5#show ip route ospf (R1-R5 links connected)

O 10.0.0.0 [110/2] via 192.168.0.26, 00:09:20, FastEthernet0/1

172.16.0.0/24 is subnetted, 1 subnets

O 172.16.20.0 [110/2] via 192.168.0.17, 00:08:35, FastEthernet0/0

192.168.0.0/30 is subnetted, 8 subnets

O 192.168.0.0 [110/2] via 192.168.0.5, 00:08:35, FastEthernet1/0

[110/2] via 192.168.0.17, 00:08:35, FastEthernet0/0

O 192.168.0.8 [110/1563] via 192.168.0.26, 00:09:20, FastEthernet0/1

O 192.168.0.12 [110/1563] via 192.168.0.17, 00:08:35, FastEthernet0/0

O 192.168.0.20 [110/65] via 192.168.0.26, 00:09:20, FastEthernet0/1

R5#show ip route ospf (R1-R5 link disconnected)

no output was shown

R5#show ip int brief (R1-R5 link connected)

Interface IP-Address OK? Method Status Protocol

FastEthernet0/0 192.168.0.18 YES manual up up

FastEthernet0/1 192.168.0.25 YES manual up up

Ethernet0/1/0 192.168.0.30 YES manual up up

FastEthernet1/0 192.168.0.6 YES manual up up

Vlan1 unassigned YES unset administratively down down

R5#show ip ospf neighbor (R1-R5 link connected)

Neighbor ID Pri State Dead Time Address Interface

192.168.0.26 1 FULL/BDR 00:00:39 192.168.0.26 FastEthernet0/1

192.168.0.17 1 FULL/BDR 00:00:37 192.168.0.17 FastEthernet0/0

192.168.0.29 1 FULL/BDR 00:00:30 192.168.0.29 Ethernet0/1/0

192.168.0.9 1 FULL/BDR 00:00:30 192.168.0.5 FastEthernet1/0

R5#show ip ospf database

OSPF Router with ID (192.168.0.30) (Process ID 50)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count

192.168.0.26 192.168.0.26 254 0x8000000a 0x00e170 6

192.168.0.9 192.168.0.9 249 0x80000009 0x001f82 4

192.168.0.29 192.168.0.29 248 0x80000009 0x000351 5

192.168.0.30 192.168.0.30 231 0x80000015 0x00a569 4

192.168.0.17 192.168.0.17 231 0x80000016 0x00a020 5

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum

192.168.0.25 192.168.0.30 255 0x8000000b 0x0057e5

192.168.0.6 192.168.0.30 255 0x8000000c 0x00adb2

192.168.0.30 192.168.0.30 250 0x8000000d 0x005ba5

192.168.0.1 192.168.0.17 248 0x80000003 0x00f1b3

192.168.0.18 192.168.0.30 231 0x8000000e 0x0061e8

Paki · ‎02-21-2017

One more thing.

Aside of this that R1-R5 link is broken, atleast these PC(s) should PING WAN interfaces of Serial Cable. These PC(s) are not even PINGing them.

What to do?

Satwant Singh · ‎02-21-2017

I don't think it is related to ospf. do one more thing ... give the output of sh ip route ospf on R2 & R4 (Both cases up/down)

Paki · ‎02-21-2017

R2#show ip route ospf (R1-R5 link established)

O 10.0.0.0 [110/3] via 192.168.0.6, 00:57:11, FastEthernet1/0

172.16.0.0/24 is subnetted, 1 subnets

O 172.16.20.0 [110/2] via 192.168.0.1, 02:09:59, FastEthernet0/1

192.168.0.0/30 is subnetted, 8 subnets

O 192.168.0.12 [110/1563] via 192.168.0.1, 02:09:59, FastEthernet0/1

O 192.168.0.16 [110/2] via 192.168.0.1, 01:09:27, FastEthernet0/1

[110/2] via 192.168.0.6, 01:09:27, FastEthernet1/0

O 192.168.0.20 [110/66] via 192.168.0.6, 00:57:11, FastEthernet1/0

O 192.168.0.24 [110/2] via 192.168.0.6, 00:57:11, FastEthernet1/0

O 192.168.0.28 [110/11] via 192.168.0.6, 02:09:59, FastEthernet1/0

R2#show ip route ospf (R1-R5 link disconnected)

O 10.0.0.0 [110/3] via 192.168.0.6, 00:58:11, FastEthernet1/0

172.16.0.0/24 is subnetted, 1 subnets

O 172.16.20.0 [110/2] via 192.168.0.1, 02:10:59, FastEthernet0/1

192.168.0.0/30 is subnetted, 7 subnets

O 192.168.0.12 [110/1563] via 192.168.0.1, 02:10:59, FastEthernet0/1

O 192.168.0.20 [110/66] via 192.168.0.6, 00:58:11, FastEthernet1/0

O 192.168.0.24 [110/2] via 192.168.0.6, 00:58:11, FastEthernet1/0

O 192.168.0.28 [110/11] via 192.168.0.6, 02:10:59, FastEthernet1/0

R4#show ip route ospf (R1-R5 link connected)

O 10.0.0.0 [110/3] via 192.168.0.30, 01:00:03, FastEthernet0/1

172.16.0.0/24 is subnetted, 1 subnets

O 172.16.20.0 [110/4] via 192.168.0.30, 00:01:57, FastEthernet0/1

192.168.0.0/30 is subnetted, 8 subnets

O 192.168.0.0 [110/3] via 192.168.0.30, 02:12:50, FastEthernet0/1

O 192.168.0.4 [110/2] via 192.168.0.30, 02:12:50, FastEthernet0/1

O 192.168.0.8 [110/66] via 192.168.0.30, 01:01:23, FastEthernet0/1

O 192.168.0.16 [110/2] via 192.168.0.30, 00:00:03, FastEthernet0/1

O 192.168.0.24 [110/2] via 192.168.0.30, 01:00:03, FastEthernet0/1

R4#show ip route ospf (R1-R5 link disconnected)

O 10.0.0.0 [110/3] via 192.168.0.30, 00:59:08, FastEthernet0/1

172.16.0.0/24 is subnetted, 1 subnets

O 172.16.20.0 [110/4] via 192.168.0.30, 00:01:03, FastEthernet0/1

192.168.0.0/30 is subnetted, 7 subnets

O 192.168.0.0 [110/3] via 192.168.0.30, 02:11:55, FastEthernet0/1

O 192.168.0.4 [110/2] via 192.168.0.30, 02:11:55, FastEthernet0/1

O 192.168.0.8 [110/66] via 192.168.0.30, 01:00:28, FastEthernet0/1

O 192.168.0.24 [110/2] via 192.168.0.30, 00:59:08, FastEthernet0/1

Whether I remove the R1-R5 link or not, these both do not show any OSPF adjacency or neighbor detached message

Satwant Singh · ‎02-21-2017

I tried in gns3, but i have not faced any issue. Everything is working fine whether link is up or down:

R5#Sh ip route ospf (link working R1 to R5)
O 192.168.1.0/24 [110/2] via 15.1.1.1, 00:01:03, FastEthernet0/0
O 192.168.2.0/24 [110/11] via 35.1.1.1, 00:07:01, Ethernet1/3

R5#Sh ip route ospf (link disconnected R1 to R5)
O 192.168.1.0/24 [110/75] via 45.1.1.1, 00:00:08, Ethernet1/4
[110/75] via 25.1.1.1, 00:00:08, Ethernet1/2 (Now Equal cost 2 routes from R2 & R4)
O 192.168.2.0/24 [110/11] via 35.1.1.1, 00:07:30, Ethernet1/3