OSPF Adjacency Issues

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Not applicable

OSPF Adjacency Issues

We've got a Cisco 7301 routers that forms OSPF adjacencies with an HA pair of 5020 firewalls.  Recently I swapped this router out with a different router with the same IPs but different configs to test a new WAN connection.  OSPF forms up just fine with the new router.  After testing concluded and swapping back to the old router OSPF freaks out.  The adjacencies get stuck in EXSTART.  Cisco also says that this is an MTU mismatch condition, not true in my case.

Failing the firewalls over did not clear this up, tried twice.  Rebooting them did the trick.  After the reboot and a failover the adjacency was just fine.

Aug 11 00:15:14: %OSPF-5-ADJCHG: Process 200, Nbr 10.16.0.12 on GigabitEthernet0/0.200 from EXSTART to DOWN, Neighbor Down: Too many retransmissions

Aug 11 00:16:04: %OSPF-5-ADJCHG: Process 200, Nbr 10.16.1.20 on GigabitEthernet0/0.200 from DOWN to DOWN, Neighbor Down: Ignore timer expired

Aug 11 00:17:14: %OSPF-5-ADJCHG: Process 200, Nbr 10.16.0.12 on GigabitEthernet0/0.200 from EXSTART to DOWN, Neighbor Down: Too many retransmissions

Wondering if anyone else has seen this type of issue, or at least has any suggestions on how to get the adjacency to form without having to reboot.

L5 Sessionator

Re: OSPF Adjacency Issues

what software version are you on

L5 Sessionator

Re: OSPF Adjacency Issues

Do you have jumbo frames enabled. There was an issue which was seen on release 4.1.3 which got fixed in 4.1.7.

Bug 40409: Palo Alto Networks firewall not able to setup an OSPF link when using P2P to a Cisco router with jumbo-frames enabled, but broadcast mode does work. Issue with to P2P mode only, which has been fixed.

Another issue was seen in release 4.1.7 which has been fixed in 4.1.13 and 5.0.4

Bug 45687:  When HA fails over from the active device to the passive device, it took more than a couple of minutes to re-establish the OSPF adjacency when the OSPF database was large. This occurred in rare situations and was due to the new active device sending redundant Database Description (DD) packets. If the neighbor OSPF router cannot handle the duplicate OSPF DD packets, the OSPF database exchange can be aborted multiple times. This issue has been resolved with this release such that the redundant DD packets are not sent.

I am not sure if you are running into any of the above issue.

Thanks

Not applicable

Re: OSPF Adjacency Issues

Running 4.1.7-h2...should have included that.

L5 Sessionator

Re: OSPF Adjacency Issues

Just verify what the link types were configured on the cisco and the firewall. Its recommended that if using the Ethernet cables to connect to the cisco router, select the link type as "broadcast", and not "p2p" or "p2mp"

Plus, its always recommended to use graceful restart when deploying OSPF in a cluster. The feature, “graceful-restart” for OSPF is currently not supported by the PAN-FW.  Since “graceful-restart” is not supported for OSPF, the routes will not be retained in the FIB once an OSPF neighbor goes down. Moreover, since the routes have been purged, traffic  reliant upon these routes will be incorrectly forward out the default route or dropped.

L5 Sessionator

Re: OSPF Adjacency Issues

Can you make sure to see if there isn't a clean up/deny all/same zone deny rule at the bottom.

Not applicable

Re: OSPF Adjacency Issues

Thanks for the posts so far. 

There are no deny's at the bottom of the rule base (nor do I see blocks from the router or firewall when trying to establish).

We also are not using graceful restart, and the PA interfaces are set for broadcast.

L5 Sessionator

Re: OSPF Adjacency Issues

We have to simulate the issue again and look at the "routed" logs on all the 3 firewalls ( PANFW cluster and the Cisco router )  to investigate the root cause.

Highlighted
L0 Member

Re: OSPF Adjacency Issues

I am running into the same issue on a A/P HA set of PA-2020's uplinked to HP L3 switches.  In my case rather than reboot I run 'debug routing reset'

At that point the adjacency re-establishes and all is well.   One thing I did notice is following the routed reset an additional log is created indicating 2-way communication with peer followed by OSPF full adjacency log.    I do not get the 2-way log following HA events.

L4 Transporter

Re: OSPF Adjacency Issues

Hello,

Even if the MTU seems to be the same on both devices, you probably have a MTU mismatch (what's on you see in the log).

On the Cisco device, you can add the following command under the "faulty" OSPF interface:

ip ospf mtu-ignore

This command should be also present on the PA device, except that PA doesn't support this feature !

REM: For PA team, please add the support for this feature on your device.

As I can see you're using sub-interface on the PA. So the MTU will not match the physical interface of your cisco device...

PS: If you are using subinterface on the Cisco device, MTU should match

Regards,

HA

CCIE#13029 (R&S, Security)

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