An EGP import rule. Each rule is keyed by the
Autonomous System of the EGP neighbor and the IP
network of the route learned from the neighbor.
The AS can be set to a wild card as can the IP
network. When a route is learned from a neighbor,
the most specific import rule is applied to the
route. The route is either accepted or discarded
and its metrics are applied according to the rule.
An exact match on the AS and IP network is the most
exact rule. An exact match on the AS and a wild
card match on the IP network is the 2nd most exact
rule. A wild card match on the AS and an exact match
on the IP network is the 3rd most exact match.
Finally, a total wild card match is the least exact
rule.