Novell NETWARE 6-DOCUMENTATION Manual page 1877

IP Routing Information Filters
IP Incoming Filters
IP Outgoing Filters
IP routing information filters let the router restrict the routes that it accepts
from neighbors (incoming filters) and limit the advertised routes (outgoing
filters). The router can use RIP, Open Shortest Path First (OSPF), or Exterior
Gateway Protocol (EGP) to exchange routing information with other
neighboring routers, as follows:
RIP filters control the propagation of routing information and hide the
existence of specific IP networks from other routers.
OSPF filters control the propagation of routing information from non-
OSPF domains (RIP, EGP, and so on) to the OSPF domain.
EGP filters define the routes a router can share with other EGP peers.
IP incoming filters let the router restrict information about the routes it accepts
from its neighbors. Filtered routes are not recorded in the local forwarding
table and cannot be propagated to other routers or hosts. The filter includes the
destination network and the source of the route. The source identifies the
interface, interface group, or WAN connection from which the route
information was received or the address of the router that provided the
information.
You can apply IP incoming filters only to RIP and EGP routes. You cannot
filter routes to directly connected networks. Incoming filters do the following:
RIP incoming filters restrict the acceptance of routing information from
other RIP routers.
EGP incoming filters restrict the routes accepted from the EGP peers.
IP outgoing filters restrict the propagation of route information from the
router. You can also use them to control the flow of routes between the routing
protocols. An outgoing filter specifies a route and a potential recipient of the
information. The recipient is an outbound interface, an interface group, a
WAN connection, or the IP address of another router.
17
Understanding