Huawei Quidway S6500 Series Operation Manual page 266

Operation Manual - Routing Protocol
Quidway S6500 Series Ethernet Switches
Chapter 7 IP Routing Policy Configuration
7.1 Brief Introduction to IP Routing Policy
When a router distributes or receives routing information, it possibly needs to
implement some policies to filter the routing information, so as to receive or distribute
the routing information which can meet the specified condition only. A routing protocol,
e.g. RIP, maybe need import the routing information discovered by other protocols to
enrich its routing knowledge. While importing the routing information, it possibly only
needs import the information meeting the conditions and set some special attributes to
make them meet its requirement.
For implementing the routing policy, you need define a set of matching rules by
specifying the characteristics of the routing information to be filtered. You can set the
rules based on such attributes like destination address and source address of the
information. The matching rules can be set in advance and then used in the routing
policy to advertise, receive and import the route information.
In Quidway S6500 Series Ethernet Switches, five kinds of filters, Route-policy, acl,
as-path, community-list, and ip-prefix, are provided to be called by the routing protocols.
The following sections introduce these filters respectively.
I. Route-policy
Route policy is used for matching some attributes in 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 match testing, and
the nodes will be matched in a sequence-number-based order on the basis of. Each
node comprises a set of if-match and apply clauses. The if-match clauses define the
matching rules and the matching objects are some attributes of routing information. The
relationship of if-match clauses for a node is "AND". As a result, a match can be found
unless all the matching conditions specified by the if-match clauses are satisfied. The
apply clause specifies the actions performed after the node match test, concerning the
attribute settings of the route information.
The relationships of different nodes in a route-policy are "OR". As a result, the system
will examine the nodes in the route-policy in sequence. Once the route is permitted by a
node in the route-policy, it will pass the matching test of the route-policy without
entering the test of the next node.
Huawei Technologies Proprietary
7-1
Chapter 7 IP Routing Policy Configuration