Help with a BASIC OSPF interarea ping issue

Hi All,
This is driving me mad but i hope you can help, im sure its simple bit i cant work it out.

I have 3 routers connected via Serial to each other.

R1 -> Area 1 (Stub - No Summary) -> R2 -> Area 0 -> R3 -> Area 2 (On loopback)

R1's Routing table is like so:-

Gateway of last resort is 192.168.4.6 to network 0.0.0.0

192.168.4.0/30 is subnetted, 1 subnets
C 192.168.4.4 is directly connected, Serial1/0
O*IA 0.0.0.0/0 [110/65] via 192.168.4.6, 00:54:05, Serial1/0

R2's is

Gateway of last resort is not set

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/1
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/65] via 192.168.72.5, 00:13:20, Serial1/1
192.168.4.0/30 is subnetted, 1 subnets
C 192.168.4.4 is directly connected, Serial1/0

and R3's is

Gateway of last resort is not set

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
192.168.4.0/30 is subnetted, 1 subnets
O IA 192.168.4.4 [110/128] via 192.168.72.6, 00:03:28, Serial1/0

Now i cant ping R3 From R1 , i.e. Ping 3.3.3.3 (Loopback on R3) is not working, neither is 172.168.72.5 (Serial link to R2 on R3)

R1's Config is:-

interface Serial1/0
ip address 192.168.4.5 255.255.255.252
no fair-queue
serial restart-delay 0
clock rate 64000
!
router ospf 1
log-adjacency-changes
area 1 stub
network 192.168.4.4 0.0.0.3 area 1

R2's is

interface Serial1/0
ip address 192.168.4.6 255.255.255.252
no fair-queue
serial restart-delay 0
!
interface Serial1/1
ip address 192.168.72.6 255.255.255.252
serial restart-delay 0
!
router ospf 1
log-adjacency-changes
area 1 stub no-summary
redistribute connected
redistribute static
network 192.168.4.4 0.0.0.3 area 1
network 192.168.72.4 0.0.0.3 area 0

And the config of R3 is as follows:-

interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface Serial1/0
ip address 192.168.72.5 255.255.255.252
no fair-queue
serial restart-delay 0
clock rate 64000
!
router ospf 1
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 2
network 192.168.72.4 0.0.0.3 area 0

I CAN ping 172.168.72.4 from R1 and the routing tables all show

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/1

but not 192.168.72.4 /30 as i would expect, which kind of makes it look like its advertising the wrong subnet but then why is .4 showing?

Can anyone help point me in the right direction here, why can i ping and how can i fix it?

Thanks

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Comments

Mrock4

I recreated your topology and pasted your configs in dynamips and had full-connectivity. The only change I made was add a loopback of 1.1.1.1 to R1..and advertise it into the OSPF process.

Pash

TheBlueRaja wrote:

Hi All,
This is driving me mad but i hope you can help, im sure its simple bit i cant work it out.

I have 3 routers connected via Serial to each other.

R1 -> Area 1 (Stub - No Summary) -> R2 -> Area 0 -> R3 -> Area 2 (On loopback)

R1's Routing table is like so:-

Gateway of last resort is 192.168.4.6 to network 0.0.0.0

192.168.4.0/30 is subnetted, 1 subnets
C 192.168.4.4 is directly connected, Serial1/0
O*IA 0.0.0.0/0 [110/65] via 192.168.4.6, 00:54:05, Serial1/0

R2's is

Gateway of last resort is not set

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/1
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/65] via 192.168.72.5, 00:13:20, Serial1/1
192.168.4.0/30 is subnetted, 1 subnets
C 192.168.4.4 is directly connected, Serial1/0

and R3's is

Gateway of last resort is not set

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
192.168.4.0/30 is subnetted, 1 subnets
O IA 192.168.4.4 [110/128] via 192.168.72.6, 00:03:28, Serial1/0

Now i cant ping R3 From R1 , i.e. Ping 3.3.3.3 (Loopback on R3) is not working, neither is 172.168.72.5 (Serial link to R2 on R3)

R1's Config is:-

interface Serial1/0
ip address 192.168.4.5 255.255.255.252
no fair-queue
serial restart-delay 0
clock rate 64000
!
router ospf 1
log-adjacency-changes
area 1 stub
network 192.168.4.4 0.0.0.3 area 1

R2's is

interface Serial1/0
ip address 192.168.4.6 255.255.255.252
no fair-queue
serial restart-delay 0
!
interface Serial1/1
ip address 192.168.72.6 255.255.255.252
serial restart-delay 0
!
router ospf 1
log-adjacency-changes
area 1 stub no-summary
redistribute connected
redistribute static
network 192.168.4.4 0.0.0.3 area 1
network 192.168.72.4 0.0.0.3 area 0

And the config of R3 is as follows:-

interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface Serial1/0
ip address 192.168.72.5 255.255.255.252
no fair-queue
serial restart-delay 0
clock rate 64000
!
router ospf 1
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 2
network 192.168.72.4 0.0.0.3 area 0

I CAN ping 172.168.72.4 from R1 and the routing tables all show

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/1

but not 192.168.72.4 /30 as i would expect, which kind of makes it look like its advertising the wrong subnet but then why is .4 showing?

Can anyone help point me in the right direction here, why can i ping and how can i fix it?

Thanks

Unless you pasted it wrong you have two directly connected interfaces with the same IP, is your configuration 100% correct? Other than that, it looks ok.

Mrock4

His interfaces are 4.5 and 4.6, but on the 4.4 network, which is why they show up in the routing tables as such.

tech-airman

TheBlueRaja wrote:

Hi All,
This is driving me mad but i hope you can help, im sure its simple bit i cant work it out.

I have 3 routers connected via Serial to each other.

R1 -> Area 1 (Stub - No Summary) -> R2 -> Area 0 -> R3 -> Area 2 (On loopback)

R1's Routing table is like so:-

Gateway of last resort is 192.168.4.6 to network 0.0.0.0

192.168.4.0/30 is subnetted, 1 subnets
C 192.168.4.4 is directly connected, Serial1/0
O*IA 0.0.0.0/0 [110/65] via 192.168.4.6, 00:54:05, Serial1/0

R2's is

Gateway of last resort is not set

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/1
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/65] via 192.168.72.5, 00:13:20, Serial1/1
192.168.4.0/30 is subnetted, 1 subnets
C 192.168.4.4 is directly connected, Serial1/0

and R3's is

Gateway of last resort is not set

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
192.168.4.0/30 is subnetted, 1 subnets
O IA 192.168.4.4 [110/128] via 192.168.72.6, 00:03:28, Serial1/0

Now i cant ping R3 From R1 , i.e. Ping 3.3.3.3 (Loopback on R3) is not working, neither is 172.168.72.5 (Serial link to R2 on R3)

R1's Config is:-

interface Serial1/0
ip address 192.168.4.5 255.255.255.252
no fair-queue
serial restart-delay 0
clock rate 64000
!
router ospf 1
log-adjacency-changes
area 1 stub
network 192.168.4.4 0.0.0.3 area 1

R2's is

interface Serial1/0
ip address 192.168.4.6 255.255.255.252
no fair-queue
serial restart-delay 0
!
interface Serial1/1
ip address 192.168.72.6 255.255.255.252
serial restart-delay 0
!
router ospf 1
log-adjacency-changes
area 1 stub no-summary
redistribute connected
redistribute static
network 192.168.4.4 0.0.0.3 area 1
network 192.168.72.4 0.0.0.3 area 0

And the config of R3 is as follows:-

interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface Serial1/0
ip address 192.168.72.5 255.255.255.252
no fair-queue
serial restart-delay 0
clock rate 64000
!
router ospf 1
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 2
network 192.168.72.4 0.0.0.3 area 0

I CAN ping 172.168.72.4 from R1 and the routing tables all show

192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial1/1

but not 192.168.72.4 /30 as i would expect, which kind of makes it look like its advertising the wrong subnet but then why is .4 showing?

Can anyone help point me in the right direction here, why can i ping and how can i fix it?

Thanks

TheBlueRaja,

Try the following steps....

R3>enable
R3#configuration terminal
R3(config)#interface loopback 0
R3(config-if)#ip ospf network point-to-point
R3(config-if)#exit
R3(config)#exit
R3#

Mrock4

tech-airman wrote:

TheBlueRaja,

Try the following steps....

R3>enable
R3#configuration terminal
R3(config)#interface loopback 0
R3(config-if)#ip ospf network point-to-point
R3(config-if)#exit
R3(config)#exit
R3#

Except with "configure" not configuration!

TheBlueRaja

Mrock4 wrote:

His interfaces are 4.5 and 4.6, but on the 4.4 network, which is why they show up in the routing tables as such.

Unless i'm mistaken, they are 4.5 and 4.6 on the 4.4 network on a /30 (.252). This means that 4.5 and 4.6 are valid hosts does it not? If so 172.168.72.4 is the network not 172.168.72.0 which is shown in the routing table of R2 and R3. This is confusing me....

Pash wrote:

Unless you pasted it wrong you have two directly connected interfaces with the same IP, is your configuration 100% correct? Other than that, it looks ok.

Unless im being daft i cant see this?

TheBlueRaja

tech-airman wrote:

TheBlueRaja,

Try the following steps....

R3>enable
R3#configuration terminal
R3(config)#interface loopback 0
R3(config-if)#ip ospf network point-to-point
R3(config-if)#exit
R3(config)#exit
R3#

Thanks, i'll try this and let you know - isnt Point to point the default network type though?

EDIT: Ahhh, but not on loopback.... Still not tried it yet but the next question will be why does this make a difference if it does work?

EDIT2: Sorry didnt work....

Mrock4 wrote:

I recreated your topology and pasted your configs in dynamips and had full-connectivity. The only change I made was add a loopback of 1.1.1.1 to R1..and advertise it into the OSPF process.

Strange im also using Dynamips, i tried this too and this does not work either... Can you post your R2 and R3 routing table?

Mrock4

Sure Raja. Let me set it up again, I closed it out. I'll post it shortly.

TheBlueRaja

Thanks bud!

Mrock4

R2
192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial2/0
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/65] via 192.168.4.5, 00:01:02, Serial1/0
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/65] via 192.168.72.5, 00:00:52, Serial2/0
192.168.4.0/30 is subnetted, 1 subnets
C 192.168.4.4 is directly connected, Serial1/0
R2#

NOTE** 1.1.1.1 is the R1 Loopback I created..

R3
192.168.72.0/30 is subnetted, 1 subnets
C 192.168.72.4 is directly connected, Serial2/0
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/129] via 192.168.72.6, 00:01:43, Serial2/0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback1
192.168.4.0/30 is subnetted, 1 subnets
O IA 192.168.4.4 [110/128] via 192.168.72.6, 00:01:43, Serial2/0

R1#ping 3.3.3.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/35/52 ms
R1#

And back from R3 to R1..using the loopback I created (just a habit of mine)..

R3#ping 1.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/34/60 ms
R3#

There ya go.

kryolla

Follow the packet i.e sh ip route 3.3.3.3 from R1 until you find an outgoing interface then move onto to R2 and so on then R3 back or try a traceroute and see where it is failing. Are you getting an ICMP unreachable or is your ping timeing out

TheBlueRaja

Well,
Its now working, i can only assume it was some sort of glitch as nothing has changed. I went back to the computer to check is it was ICMP unreachable or timeout and the computer had went to sleep.

Switched it back on and bang, worked right away.

I can only assume it was a UDP IO issue withing Dynamip on the "links". I dont have any other ideas or explanation... It would also explain why Mrock4's config is working and his routing table looked the same as mine.

All i can say is thanks for all the help guys and i hope i can return the favor one day.

Pash

Mrock4 wrote:

His interfaces are 4.5 and 4.6, but on the 4.4 network, which is why they show up in the routing tables as such.

hahaha good point Mrock4, this is gonna sound lame on a CCNP forum buuuut im so used to seeing /32 connected host interfaces as ive been doing tons of juniper firewall configurations recently!

Mrock4

Pash wrote:

Mrock4 wrote:

His interfaces are 4.5 and 4.6, but on the 4.4 network, which is why they show up in the routing tables as such.

hahaha good point Mrock4, this is gonna sound lame on a CCNP forum buuuut im so used to seeing /32 connected host interfaces as ive been doing tons of juniper firewall configurations recently!

No worries

..you made me look at it twice! I still type "sh run" from interface config mode on cisco devices thanks to my foundry days..