C.5 Non-broadcast, multi-access network parameters

OSPF treats a non-broadcast, multi-access network much like it treats a broadcast network. Since there may be many routers attached to the network, a Designated Router is selected for the network. This Designated Router then originates a networks links advertisement, which lists all routers attached to the non-broadcast network.

However, due to the lack of broadcast capabilities, it is necessary to use configuration parameters in the Designated Router selection. These parameters need only be configured in those routers that are themselves eligible to become Designated Router (i.e., those router's whose Router Priority for the network is non-zero):

List of all other attached routers

The list of all other routers attached to the non-broadcast network. Each router is listed by its IP interface address on the network. Also, for each router listed, that router's eligibility to become Designated Router must be defined. When an interface to a non-broadcast network comes up, the router sends Hello Packets only to those neighbors eligible to become Designated Router, until the identity of the Designated Router is discovered.

PollInterval

If a neighboring router has become inactive (Hello Packets have not been seen for RouterDeadInterval seconds), it may still be necessary to send Hello Packets to the dead neighbor. These Hello Packets will be sent at the reduced rate PollInterval, which should be much larger than HelloInterval. Sample value for a PDN X.25 network: 2 minutes.