3Com Switch 8800 Advanced Software V5 Configuration Guide

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ROUTING POLICY CONFIGURATION
A routing policy is used on a router for route inspection, filtering, attributes
modifying when routes are received, advertised, or redistributed.
When configuring routing policy, go to these sections for information you are
interested in:
■ “Introduction to Routing Policy” on page 243
■ “Routing Policy Configuration Task List” on page 245
■ “Defining Filtering Lists” on page 245
■ “Configuring a Routing Policy” on page 247
■ “Displaying and Maintaining the Routing Policy” on page 251
■ “Routing Policy Configuration Examples” on page 252
■ “Troubleshooting Routing Policy Configuration” on page 256
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The term "router" refers to a router in a generic sense or an Ethernet switch
running routing protocols in this document.
Introduction to
Routing Policy
Routing Policy A routing policy is used on the router for route inspection, filtering, attributes
modifying when routes are received, advertised, or redistributed.
When distributing or receiving routing information, a router can apply a policy to
filter routing information. For example, a router handles only routing information
that matches some criteria of a routing policy; a routing protocol redistributes
from another protocol only routes matching some criteria of a routing policy and
modifies some attributes of these routes to satisfy its needs according to the
routing policy.
To implement a routing policy, you need define a set of match criteria according to
attributes in routing information, such as destination address, advertising router’s
address and so on. The match criteria can be set beforehand and then apply them
to a routing policy for route distribution, reception and redistribution.
Filters Routing protocols can use six filters: ACL, IP prefix list, AS path ACL, community
list, extended community list and routing policy.