SNR S2989G-48TX-DC [228/553] Ip routing policy

S2989G-24TX Operation Manual

Chapter 4 Routing Protocol Related Configuration

4-3

Direct route

OSPF

110

Static route

RIP

120

OSPF ASE

150

IBGP

200

EBGP

Unknown route

255

4.1.2

IP Routing Policy

4.1.2.1 Introduction to Routing Policy

Some policies have to be applied when the router publishing and receiving routing

messages so to filter routing messages, such as only receiving or publishing routing

messages meets the specified conditions. A routing protocol maybe need redistribute

other routing messages found by other protocols such as OSPF so to increase its own

routing knowledge; when the router redistributing routing messages from other routing

protocols there may be only part of the qualified routing messages is needed, and some

properties may have to be configured to suit this protocol.

To achieve routing policy, first we have to define the characteristics of the routing

messages to be applied with routing policies, namely define a group matching rules. We

can configure by different properties in the routing messages such as destination address,

the router address publishing the routing messages. The matching rules can be previously

configured to be applied in the routing publishing, receiving and distributing policies.

Five filters are provided in switch: route-map, acl, as-path, community-list and ip-

prefix for use. We will introduce each filter in following sections:

1. route-map

For matching certain properties of the specified routing information and setting some

routing propertities when the conditions are fulfilled.

Route-map is for controlling and changing the routing messages while also controlling

the redistribution among routes. A route-map consists of a series of match and set

commands in which the match command specifies the conditions required matching, and

the set command specifies the actions to be taken when matches. The route-map is also

for controlling route publishing among different route process. It can also used on policy

routing which select different routes for the messages other than the shortest route.

A group matches and set clauses make up a node. A route-map may consist of

several nodes each of which is a unit for matching test. We match among nodes with by