Novell NETWARE 6-DOCUMENTATION Manual page 1881

AppleTalk Outgoing Route Filters
Routing information filters are also available over AppleTalk Update-based
Routing Protocol (AURP). In this case, a neighboring router can be either a
network interface (all neighbors directly connected to the cable) or all peers
on the AURP tunnel.
AppleTalk outgoing route filters can be used for networks and zones.
Incoming route filters can be used only for networks.
NOTE:
If AppleTalk networks have more than one router between them (such as
for redundant or loop routing), these routers are required to have the same filters
configured (device hiding, outgoing router, or incoming route filters). Configuring
filters in only one router does not filter out the required information.
For more information on AppleTalk routing information filters, refer to
"AppleTalk Outgoing Route Filters" on page 21
"AppleTalk Incoming Route Filters" on page 22
AppleTalk outgoing route filters limit the routing information advertised by a
router to its neighbors. A typical outgoing route filter consists of a network or
zone (the route) and the interface through which filtered advertisements are
sent. The filters affect all routers on the network to which the interface
connects.
An AppleTalk router learns only about networks that are not directly
connected through its neighbors. Because of this, neighboring routers with
enabled outgoing route filtering can limit the routing information that the
AppleTalk router receives. This effectively cuts off access from one part of the
network to another.
NOTE:
If you hide a route from a neighbor, none of the routers on the neighbor's
side of the network has any information about this route.
If the specified action is to deny routes in the filter list, the router ignores all
the route information in the filters going to the designated neighbors, but sends
all other routing information. If the specified action is to permit routes in the
filter list, the router uses only routes designated in the filter list to the specific
neighbors and ignores everything else.
Novell Internet Access Server 4.1 supports zone-based and network number-
based outgoing route filters, as discussed in the following sections.
21
Understanding