An OSPF import rule. Each rule is keyed by the IP
network of the route and the AS from which it was
learned. The Ip network and the AS can both be set
to a wild card. When an OSPF route is added to the
routing table, the most specific import rule is
applied to set the preference of the route. An
exact match on the Ip network and on the AS is the
most exact rule. An exact match on the IP network
and a wild card match on the AS is the 2nd most
exact rule. A wild card match on both the on the
AS and IP network is the next and least exact
rule.