1-2FiltersThere are six types of filters: ACL, IP prefix list, and route policy.ACLACL involves IPv4 ACL and IPv6 ACL. An ACL is configured to match the destinations or next hops ofrouting information.For ACL configuration, refer to ACL configuration in the Security Volume.IP prefix listIP prefix list involves IPv4 and IPv6 prefix list.An IP prefix list is configured to match the destination address of routing information. Moreover, you canuse the gateway option to allow only routing information from certain routers to be received. Forgateway option information, refer to RIP Commands in the IP Routing Volume.An IP prefix list, identified by name, can comprise multiple items. Each item, identified by an indexnumber, can specify a prefix range to match. An item with a smaller index number is matched first. If oneitem is matched, the IP prefix list is passed, and the packet will not go to the next item.Route policyA route policy is used to match routing information and modify the attributes of permitted routes. It canreference the above mentioned filters to define its own match criteria.A route policy can comprise multiple nodes, which are in logic OR relationship. Each route policy nodeis a match unit, and a node with a smaller number is matched first. Once a node is matched, the routepolicy is passed and the packet will not go to the next node.A route policy node comprises a set of if-match and apply clauses.z The if-match clauses define the match criteria. The matching objects are some attributes of routinginformation. The if-match clauses of a route policy node is in logical AND relationship. That is, apacket must match all the if-match clauses of the node to pass it.z The apply clauses of the node specify the actions to be taken on the permitted packets, such asroute attribute modification.Follow these guidelines for configuring if-match and apply clauses.z If you want to implement route filtering only, you do not need to configure apply clauses.z If you do not configure any if-match clauses for a permit-mode node, the node permits all routes topass.z Configure a permit-mode node containing no if-match or apply clauses behind multipledeny-mode nodes to allow unmatched routes to pass.Route Policy ApplicationA route policy is applied on a router to filter routes when they are received, advertised or redistributedand to modify some attributes of permitted routes.Route Policy Configuration Task ListComplete the following tasks to configure a route policy:
