05-14-2008 05:14 AM - edited 03-03-2019 09:56 PM
Hello Guys
I have very strange problem to setup very simple OSPF between 3 routers in hub-spoke scenario.
Here is config from hub router in main office:
interface ATM0/1/0
no ip address
ip directed-broadcast
ip pim sparse-mode
no atm ilmi-keepalive
!
interface ATM0/1/0.1 point-to-point
ip address x.x.x.x 255.255.255.252
ip ospf network broadcast
ip ospf priority 50
pvc 0/35
encapsulation aal5snap
!
!
interface ATM0/1/0.2 point-to-point
ip address x.x.x.y 255.255.255.252
ip directed-broadcast
ip ospf network broadcast
ip ospf priority 50
pvc 0/36
encapsulation aal5snap
router ospf 10
log-adjacency-changes
network x.x.x.x 0.0.0.7 area 0
network 192.168.x.0 0.0.0.255 area 0
On the one of remote routers config is following:
interface ATM0/0/0
ip address x.x.x.x 255.255.255.252
ip directed-broadcast
ip ospf network broadcast
atm ilmi-keepalive 3
pvc 0/35
encapsulation aal5snap
!
!
router ospf 10
log-adjacency-changes
network x.x.x.x 0.0.0.3 area 0
network 192.168.y.0 0.0.0.255 area 0
Here is problem:
OSPF communication is established for the first time and after dead timer expire (in 40 sec) connection is broken and is reestablished after 10 sec. So it produce route flapping.
It is appear only on HO router and it constantly flap routes. For the remote site router everything appear OK.
I ran debug ip ospf events and got that HO router is sending hello packets but not receiving any ospf hello packet.
On the remote router hello packets are sent and received and there is no problem with routes.
Dule
Solved! Go to Solution.
05-16-2008 12:52 PM
Why you set ip ospf network broadcas on a p-t-p link?
and why "ip direct-boradcast" ??
These commands are not necessary.
What is necessary is that the remote router you configure a p-t-p subif also.
05-16-2008 12:33 PM
Dule,
Have you checked basic IP connectivity between the hub and spokes, you can ping back and forth and there is no packet loss?
Make sure MTU size on the interfaces is the same.
-serg
05-16-2008 12:52 PM
Why you set ip ospf network broadcas on a p-t-p link?
and why "ip direct-boradcast" ??
These commands are not necessary.
What is necessary is that the remote router you configure a p-t-p subif also.
05-16-2008 03:56 PM
Thank you for your response. Unfortunately to do this I had to go to remote site otherwise connection will be broken.
Anyway I solved problem by introducing Tunnel interfaces and it work fine now.
Regards
05-17-2008 02:23 AM
When you need to configure remotely and connection can be broken, prepare the configuration on a file and copy to startup-configuration (nvram). Then reboot.
With tunnels you'll have more overhead and less MTU for an application that should work fine natively.
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