I am seeing some behavior out of OSPF in non_broadcast mode that I would not expect. I haven't identified any neighbors on any interfaces, yet the spokes are forming full adjacencies with the hub. I do have inverse-arp enabled on my frame switch and I suspect that inverse-arp is 'enabling' this behavior. Can you please explain the what and the why of what I am seeing?
------------------ HUB -----------------
interface Serial1/0
description *** to Frame Switch S5 ***
ip address 172.31.11.4 255.255.255.0
encapsulation frame-relay
no fair-queue
router ospf 1
log-adjacency-changes
network 172.31.11.0 0.0.0.255 area 0
------------------Spoke1----------------
interface Serial0/0
ip address 172.31.11.1 255.255.255.0
encapsulation frame-relay
frame-relay lmi-type cisco
router ospf 1
log-adjacency-changes
network 172.31.11.0 0.0.0.255 area 0
-----------------Spoke2-----------------
interface Serial0/0
ip address 172.31.11.2 255.255.255.0
encapsulation frame-relay
end
router ospf 1
log-adjacency-changes
network 172.31.11.0 0.0.0.255 area 0
spoke2#show ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
172.31.11.4 1 FULL/BDR 00:01:48 172.31.11.4 Serial0/0
spoke2#show ip ospf int
Serial0/0 is up, line protocol is up
Internet Address 172.31.11.2/24, Area 0
Process ID 1, Router ID 172.31.11.2, Network Type NON_BROADCAST, Cost: 64
