OSPF with secondary Ip addresses

Two rules are related to the use of secondary addresses in an OSPF environment:

1.  OSPF will advertise a secondary network or subnet only if it is also running on the primary network or subnet.

2.  OSPF sees secondary networks as stub networks (networks on which there are no OSPF neighbors) and therefore will not send Hellos on them. Consequently, no adjacencies can be established on secondary networks.

With this configuration, Matisse will advertise subnet 172.19.35.0/25 to its neighbors. However, if the network area statement for 192.168.10.33 should be deleted, subnet 172.19.35.0/25 will no longer be advertised.

However, the DNS server uses Dali as its default gateway. Therefore both must be able to route packets to each other.

DNS(config)# default gateway 192.168.1.1

Now all ospf domain can reach DNS server.

Ospf will not make adjacency with secondary ip address configured. But has no problem with neighbor ship made on Secondary ip address.