Branch site's LAN not being learned via OSPF

Answered Question
Jul 10th, 2008

Hello,

If anyone can help me, it would be greatly appreciated and help my throbbing headache. I'm setting up a test environment that looks like the following.

(Branch 2821 ATM/T1)---ATM T3---(WAN 7200 )---100Mb---(Core)

The problem I'm having is that the branch LAN subnet is not populating the WAN router's OSPF database. I can ping the Branch's ATM '/30' subnet fine from core, but can not ping the LAN subnet from anywhere but the Branch router. A simple "show ip route 10.190.105.0" shows the following. Configs are attached. Any takers?

RTR0286-BLSB-WAN#show ip route 10.190.105.1

Routing entry for 10.160.0.0/11

Known via "bgp 101", distance 200, metric 0, type locally generated

Redistributing via ospf 100

Routing Descriptor Blocks:

* directly connected, via Null0

Route metric is 0, traffic share count is 1

AS Hops 0

Attachment: 
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Correct Answer by Giuseppe Larosa about 8 years 5 months ago

Hello Alex,

I supposed it could deal with ospf network type.

I'm happy to know that my suggestion was right.

Have a nice weekend

Thank you for the points you have already given me.

Giuseppe

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Richard Burts Thu, 07/10/2008 - 11:48

Alex

I believe that I see the problem. on the branch router area 10.190.105.0 is a normal area. But on the WAN router is is declared as stub:

area 10.190.105.0 stub

the mismatched area type will prevent the routers from becoming neighbors and sharing routes.

Either make it stub on the branch or make it normal area on the WAN router.

HTH

Rick

alexlembesis Thu, 07/10/2008 - 12:00

Still the same thing... Although now they ARE neighbors.

RTR0286-BLSB-WAN#show ip route 10.190.105.1

Routing entry for 10.160.0.0/11

Known via "bgp 101", distance 200, metric 0, type locally generated

Redistributing via ospf 100

Routing Descriptor Blocks:

* directly connected, via Null0

Route metric is 0, traffic share count is 1

AS Hops 0

alexlembesis Thu, 07/10/2008 - 20:24

that didn't help either :( Thanks for all of your quick responses guys. I noticed that a 'show ip ospf border-routers' shows nothing...

here's a show ip ospf database from the branch router...

Branch#show ip ospf database

OSPF Router with ID (10.189.251.218) (Process ID 100)

Router Link States (Area 10.190.105.0)

Link ID ADV Router Age Seq# Checksum Link count

10.161.254.2 10.161.254.2 810 0x80000020 0x000550 2

10.189.251.218 10.189.251.218 809 0x80000002 0x007FB6 2

Net Link States (Area 10.190.105.0)

Link ID ADV Router Age Seq# Checksum

10.189.251.218 10.189.251.218 809 0x80000001 0x004472

Summary Net Link States (Area 10.190.105.0)

Link ID ADV Router Age Seq# Checksum

0.0.0.0 10.161.254.2 1540 0x80000001 0x00454C

Richard Burts Fri, 07/11/2008 - 04:17

Alex

Some additional information might be helpful. Would you post the output of show ip interface brief, and also show ip ospf interface (and while we are at it perhaps the output of show ip ospf)?

There is a network statement that should include 10.190.105.1 but it is not showing up in the link state data base. I wonder if there is some issue with that interface - is it perhaps in the state of up/down or is there some reason why it is not in the link state data base of the branch router?

HTH

Rick

alexlembesis Fri, 07/11/2008 - 05:06

Rick,

As you requested.

Branch#show ip int brief

Interface IP-Address OK? Method Status Protocol

GigabitEthernet0/0 10.190.105.1 YES manual up up

GigabitEthernet0/1 unassigned YES NVRAM administratively down down

ATM0/1/0 10.189.251.218 YES NVRAM up up

********************

Branch#show ip ospf interface

GigabitEthernet0/0 is up, line protocol is up

Internet Address 10.190.105.1/24, Area 10.190.105.0

Process ID 100, Router ID 10.189.251.218, Network Type BROADCAST, Cost: 1

Transmit Delay is 1 sec, State DR, Priority 1

Designated Router (ID) 10.189.251.218, Interface address 10.190.105.1

No backup designated router on this network

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

oob-resync timeout 40

Hello due in 00:00:06

Supports Link-local Signaling (LLS)

Cisco NSF helper support enabled

IETF NSF helper support enabled

Index 1/1, flood queue length 0

Next 0x0(0)/0x0(0)

Last flood scan length is 0, maximum is 0

Last flood scan time is 0 msec, maximum is 0 msec

Neighbor Count is 0, Adjacent neighbor count is 0

Suppress hello for 0 neighbor(s)

ATM0/1/0 is up, line protocol is up

Internet Address 10.189.251.218/30, Area 10.190.105.0

Process ID 100, Router ID 10.189.251.218, Network Type NON_BROADCAST, Cost: 65

Transmit Delay is 1 sec, State DR, Priority 1

Designated Router (ID) 10.189.251.218, Interface address 10.189.251.218

Backup Designated router (ID) 10.161.254.2, Interface address 10.189.251.217

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

oob-resync timeout 40

Hello due in 00:00:03

Supports Link-local Signaling (LLS)

Cisco NSF helper support enabled

IETF NSF helper support enabled

Index 2/2, flood queue length 0

Next 0x0(0)/0x0(0)

Last flood scan length is 1, maximum is 157

Last flood scan time is 0 msec, maximum is 4 msec

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with neighbor 10.161.254.2 (Backup Designated Router)

Suppress hello for 0 neighbor(s)

***************

Branch#show ip ospf

Routing Process "ospf 100" with ID 10.189.251.218

Start time: 02:10:18.016, Time elapsed: 20:21:41.960

Supports only single TOS(TOS0) routes

Supports opaque LSA

Supports Link-local Signaling (LLS)

Supports area transit capability

Router is not originating router-LSAs with maximum metric

Initial SPF schedule delay 5000 msecs

Minimum hold time between two consecutive SPFs 10000 msecs

Maximum wait time between two consecutive SPFs 10000 msecs

Incremental-SPF disabled

Minimum LSA interval 5 secs

Minimum LSA arrival 1000 msecs

LSA group pacing timer 240 secs

Interface flood pacing timer 33 msecs

Retransmission pacing timer 66 msecs

Number of external LSA 0. Checksum Sum 0x31F690

Number of opaque AS LSA 0. Checksum Sum 0x000000

Number of DCbitless external and opaque AS LSA 0

Number of DoNotAge external and opaque AS LSA 0

Number of areas in this router is 1. 0 normal 1 stub 0 nssa

Number of areas transit capable is 0

External flood list length 0

IETF NSF helper support enabled

Cisco NSF helper support enabled

Area 10.190.105.0

Number of interfaces in this area is 2

It is a stub area

Area has no authentication

SPF algorithm last executed 00:01:59.280 ago

SPF algorithm executed 3 times

Area ranges are

Number of LSA 4. Checksum Sum 0x140E984

Number of opaque link LSA 0. Checksum Sum 0x000000

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 0

Flood list length 0

Richard Burts Fri, 07/11/2008 - 07:20

Alex

This is quite puzzling. The output that you posted here shows that Gig0/0 is in the right state and that it is an active OSPF interface (and the branch router is the DR for the segment, as would be expected). But the output of the OSPF link state data base which you previously posted does not show this network in the link state data base. Is it possible that the content of the link state data base has changed and that the network is now included in the data base?

HTH

Rick

alexlembesis Fri, 07/11/2008 - 08:05

Yeah i'm having a helluva time figuring this out. I got the WAN router to see the Branch's LAN subnet for about 10 seconds when I changed the ospf network type on the GigabitEthernet interface to point-to-multipoint. Then out of no where, DEAD... back to Null0. Excuse me for the long post... Does this mean anything?

*Jul 11 16:06:01 UTC: OSPF: end of Wait on interface GigabitEthernet0/0

*Jul 11 16:06:01 UTC: OSPF: DR/BDR election on GigabitEthernet0/0

*Jul 11 16:06:01 UTC: OSPF: Elect BDR 10.189.251.218

*Jul 11 16:06:01 UTC: OSPF: Elect DR 10.189.251.218

*Jul 11 16:06:01 UTC: OSPF: Elect BDR 0.0.0.0

*Jul 11 16:06:01 UTC: OSPF: Elect DR 10.189.251.218

*Jul 11 16:06:01 UTC: DR: 10.189.251.218 (Id) BDR: none

*Jul 11 16:06:01 UTC: OSPF: Send hello to 224.0.0.5 area 10.190.105.0 on GigabitEthernet0/0 from 10.190.105.1

*Jul 11 16:06:02 UTC: OSPF: No full nbrs to build Net Lsa for interface GigabitEthernet0/0

*Jul 11 16:06:02 UTC: OSPF: Rcv hello from 10.161.254.2 area 10.190.105.0 from ATM0/1/0 10.189.251.217

*Jul 11 16:06:02 UTC: OSPF: End of hello processing

*Jul 11 16:06:03 UTC: OSPF: Send hello to 10.189.251.217 area 10.190.105.0 on ATM0/1/0 from 10.189.251.218

Branch(config-if)#

Branch(config-if)#

*Jul 11 16:06:11 UTC: OSPF: Send hello to 224.0.0.5 area 10.190.105.0 on GigabitEthernet0/0 from 10.190.105.1

*Jul 11 16:06:12 UTC: OSPF: Rcv hello from 10.161.254.2 area 10.190.105.0 from ATM0/1/0 10.189.251.217

*Jul 11 16:06:12 UTC: OSPF: End of hello processing

*Jul 11 16:06:13 UTC: OSPF: Send hello to 10.189.251.217 area 10.190.105.0 on ATM0/1/0 from 10.189.251.218

*Jul 11 16:06:21 UTC: OSPF: Send hello to 224.0.0.5 area 10.190.105.0 on GigabitEthernet0/0 from 10.190.105.1

*Jul 11 16:06:22 UTC: OSPF: Rcv hello from 10.161.254.2 area 10.190.105.0 from ATM0/1/0 10.189.251.217

*Jul 11 16:06:22 UTC: OSPF: End of hello processing

*Jul 11 16:06:23 UTC: OSPF: Send hello to 10.189.251.217 area 10.190.105.0 on ATM0/1/0 from 10.189.251.218

Branch#show ip ospf database

OSPF Router with ID (10.189.251.218) (Process ID 100)

Router Link States (Area 10.190.105.0)

Link ID ADV Router Age Seq# Checksum Link count

10.161.254.2 10.161.254.2 158 0x8000006A 0x00709A 2

10.189.251.218 10.189.251.218 401 0x80000002 0x007FB6 2

10.190.105.1 10.190.105.1 2247 0x80000003 0x0055B6 2

Net Link States (Area 10.190.105.0)

Link ID ADV Router Age Seq# Checksum

10.189.251.218 10.189.251.218 401 0x80000001 0x004472

Summary Net Link States (Area 10.190.105.0)

Link ID ADV Router Age Seq# Checksum

0.0.0.0 10.161.254.2 1403 0x80000017 0x001962

Branch#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface

10.161.254.2 1 FULL/BDR 00:00:30 10.189.251.217 ATM0/1/0

tdrais Fri, 07/11/2008 - 08:17

I am unclear why but I at time will not see all the link information in the show ip ospf database command. I have many times had to specify the router parm to get this

So it may be helpful to issue

sh ip ospf database router 10.189.251.218

both on the branch router and the 7200 on the far end of the ATM. In theory it should be identical. You want to look for the lan subnet in this display. Since it is a OSPF interface it has to be someplace you would think.

Now if it is there on the 7200 router in particular then its a matter of determining why its does get placed in the routing table.

Richard Burts Fri, 07/11/2008 - 08:27

Alex

There have been enough changes that perhaps it would be helpful to post the current config (especially of the branch) again.

It occurs to me to wonder if you might be doing any kind of vrf processing? Perhaps the complete router config might help us to understand the context better.

HTH

Rick

Giuseppe Larosa Fri, 07/11/2008 - 09:23

Hello Alex,

from your original post

core router:

interface ATM1/0.8 point-to-point

bandwidth 1536

ip address 10.189.251.217 255.255.255.252

pvc 0/41

vbr-nrt 1535 1535 1

encapsulation aal5snap

the ospf network type on core is point-to-point

on the branch

interface ATM0/1/0

description ATM-to-WAN

bandwidth 1536

ip address 10.189.251.218 255.255.255.252

ip ospf hello-interval 10

no scrambling-payload

no atm auto-configuration

I think this a NBMA ospf network type and it s.

from sh ip ospf interface

Process ID 100, Router ID 10.189.251.218, >>Network Type NON_BROADCAST, Cost: 65

Try to move your configuration to an atm subinterface and makes it point-to-point it should solve your issue.

Hope to help

Giuseppe

alexlembesis Fri, 07/11/2008 - 10:16

That did the trick! Thanks everyone! I was VPN'd in till a little past midnight trying to figure this one out... now I'm kicking myself because it was something so simple! Oh well, at least it's friday! Have a good weekend!

alexlembesis Fri, 07/11/2008 - 10:18

oh crap,

Giuseppe, I forgot to check the "resolved my problem" box. Would you be a sport and just post something real quick so you get the credit? Thanks.

Correct Answer
Giuseppe Larosa Fri, 07/11/2008 - 12:10

Hello Alex,

I supposed it could deal with ospf network type.

I'm happy to know that my suggestion was right.

Have a nice weekend

Thank you for the points you have already given me.

Giuseppe

Richard Burts Fri, 07/11/2008 - 10:28

Alex

Thanks for posting the configs. I have found one more thing that does not match. On the WAN router the area is configured like this:

area 10.190.105.0 stub no-summary

but on the branch router it is configured as stub (but not no-summary). I would suggest that you update the branch to agree with the WAN by adding no-summary to the area.

And I think that the suggestion from Giuseppe is also a good thing to make match.

HTH

Rick

sdoremus33 Fri, 07/11/2008 - 11:51

Giuseppe,

So am I correct in assuming that on the Branch router you add a subinterface

Ex interface ATM1/0.100 point-to-point

fixed the issue

Giuseppe Larosa Fri, 07/11/2008 - 12:13

Hello,

yes I meant to add a point-to-point subinterface on the branch router in order to match the ospf network type with the core router.

But I don't know what exactly Alex did.

Best Regards

Giuseppe

alexlembesis Fri, 07/11/2008 - 14:17

I moved the ip and pvc config from the physical interface to a sub-interface (atm0/1/0.8). That fixed the issue. However, when I had the physical interface configured, I tried using "ip ospf network point-to-point" and that had no effect. Any clue why that wouldn't have solved my issue?

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