OSPF Link issue

harisapkota123 · ‎04-27-2012

Dear All,

I have a mistirious problem in OSPF routing. please help me fixing this issue.

RA and RB is directly connected with Radio Link which is advertised with OSPF.

Sometimes link between RA and RB goes unreachable but link is fine..

Another Hint: when i issue show ip ospf neighbor command for serveral times, dead interval doesn't decrease for some moments, after some moments it starts decreasing.

Is there any issue with Radio Link or routing.

Thanks in advance

Giuseppe Larosa · ‎04-27-2012

Hello Hari,

in your network scenario the routers' interfaces are connected to the ethernet port of the radio link transceiver so physical layer (OSI 1) is always up/up as the true ethernet neighbor is the the radio link transceiver.

To understand if there are connectivity issues on the radio link that may affect the state of OSPF adjacency you can use the following show command

show ip ospf neighbor detail

that provides the OSPF adjacency uptime so you can see what is happening.

if you see that OSPF flaps you can further check with

debug ip ospf adj

to see activity on routers

I have no clue about your note about dead interval stucked for some time in show ip ospf neighbor output, However, you need to check OSPF neighborship uptime at first.

if OSPF flaps on the radio link from time to time you should consider adding an ICMP probe to check the link.

Edit: see IP SLA document

https://supportforums.cisco.com/docs/DOC-6078

Hope to help

Giuseppe