Implementing Import Policies - 3Com 4007 Implementation Manual

OSPF Routing Policies 493
Implementing Import Import policies control which non-self-originated routes (RIP external
routes) are accepted and stored in the routing table. Non-self-originated
Policies
means that the router itself did not originate the route; it learned the
route from an external link state advertisement. You can also adjust the
cost of each route that is accepted into the routing table. Using RIP, you
can define which external routes (for example, RIP) a router advertises
and imports into the OSPF link state database. They are self-originated
but must be external to OSPF. Do not reset these modules for several
minutes after making configuration changes.
Because all routers within the same OSPF area must maintain similar
databases, all routers must receive all link state advertisements that are
sent over the network, and store those advertisements in their link state
databases. By defining an import policy, however, you can control what
routes from a router's external link state database are migrated to its
routing table.
When you define an import policy, you specify a set of criteria. When a
the router receives an external link state advertisement, it consults its
routing policies to determine if the route specified in that advertisement
matches any of the defined policies criteria, and, if so, applies to the
route the actions that are defined by the policy.