Saturday, April 9, 2011

wirless environment OSPF neigbor issue.

This is setup is simple point to point but the physical transport medium is wireless.

when i enable the ospf neighbor getting up but frequently the ospf neighbor up & down.
Apr 9 08:09:33.719 LKT: %OSPF-5-ADJCHG: Process 10, Nbr 192.168.61.192 on Vlan2 from FULL to DOWN, Neighbor Down: Dead timer expired
Apr 9 08:09:33.731 LKT: %OSPF-5-ADJCHG: Process 10, Nbr 192.168.61.192 on Vlan2 from LOADING to FULL, Loading Done
Apr 9 08:12:23.720 LKT: %OSPF-5-ADJCHG: Process 10, Nbr 192.168.61.192 on Vlan2 from FULL to DOWN, Neighbor Down: Dead timer expired
Apr 9 08:12:33.735 LKT: %OSPF-5-ADJCHG: Process 10, Nbr 192.168.61.192 on Vlan2 from LOADING to FULL, Loading Done
Apr 9 08:15:13.721 LKT: %OSPF-5-ADJCHG: Process 10, Nbr 192.168.61.192 on Vlan2 from FULL to DOWN, Neighbor Down: Dead timer expired
Apr 9 08:15:23.737 LKT: %OSPF-5-ADJCHG: Process 10, Nbr 192.168.61.192 on Vlan2 from LOADING to FULL, Loading Done
Apr 9 08:19:43.729 LKT: %OSPF-5-ADJCHG: Process 10, Nbr 192.168.61.192 on Vlan2 from FULL to DOWN, Neighbor Down: Dead timer expired
Apr 9 08:19:53.740 LKT: %OSPF-5-ADJCHG: Process 10, Nbr 192.168.61.192 on Vlan2 from LOADING to FULL, Loading Done

I've confirmed there is no link failure but the hello packets are not received and the dead timer expired. I'm not sure where the problem, but i assume the problem is some multicast supporting on the wireless bridge devices . But this can be fixed using uni-cast neighbor establishment.
change the interface network type to NBMA
#ip ospf network ?
broadcast Specify OSPF broadcast multi-access network
non-broadcast Specify OSPF NBMA network
point-to-multipoint Specify OSPF point-to-multipoint network
point-to-point Specify OSPF point-to-point network
and in the ospf process define the neighbor statically this makes the unicast hello which solve this problem.
(config-router)#neighbor ?
A.B.C.D Neighbor address