4-2
For ACL configuration, refer to the part discussing ACL.
IP-prefix list
IP-prefix list plays a role similar to ACL. But it is more flexible than ACL and easier to understand. When
IP-prefix list is applied to filter routing information, its matching object is the destination address field in
routing information. Moreover, with IP-prefix list, you can use the
gateway
option to specify that only
routing information advertised by certain routers will be received.
An IP-prefix list is identified by its IP-prefix name. Each IP-prefix list can contain multiple entries, and
each entry, identified by an index-number, can independently specify the match range in the network
prefix form. An index-number specifies the matching sequence in the IP-prefix list.
There is an OR relationship between entries. During the matching, the router checks entries identified
by index-number in ascending order. Once an entry is matched, the IP-prefix list filtering is passed and
no other entries will be checked.
Route policy
A route policy is used to match some attributes with given routing information and the attributes of the
information will be set if the conditions are satisfied.
A route policy can comprise multiple nodes. Each node is a unit for matching test, and the nodes will be
matched in ascending order of their node numbers. Each node comprises a set of
if-match
and
apply
clauses. The
if-match
clauses define the matching rules. The matching objects are some attributes of
routing information. The relationship among the
if-match
clauses for a node is “AND”. As a result, a
matching test against a node is successful only when all the matching conditions specified by the
if-match
clauses in the node are satisfied. The
apply
clauses specify the actions performed after a
matching test against the node is successful, and the actions can be the attribute settings of routing
information.
There is an OR relationship between different nodes in a route policy. As a result, the system examines
the nodes in the route policy in sequence, and once the route matches a node in the route policy, it will
pass the matching test of the route policy without entering the test of the next node.
IP Route Policy Configuration Task List
Complete the following tasks to configure an IP route policy:
Task
Remarks
Defining a Route Policy
Required
Route Policy Configuration
Defining if-match Clauses and
apply Clauses
Required
IP-Prefix Configuration
Required
Route Policy Configuration
A route policy is used to match given routing information or some attributes of routing information and
change the attributes of the routing information if the conditions are met. The above-mentioned filtering
lists can serve as the match conditions:
A route policy can comprise multiple nodes and each node comprises:
