Route Policy Configuration Overview
426 7705 SAR OS Router Configuration Guide
Route Policy Configuration Overview
Route policies allow you to configure routing according to specifically defined policies. You
can create policies and entries to allow or deny paths based on parameters such as source
address, destination address, protocol, and community list.
Policies can be as simple or complex as required. A simple policy can block routes for a
specific location or IP address. More complex policies can be configured using numerous
policy statement entries containing matching conditions to specify whether to accept or reject
the route, control how a series of policies are evaluated, and manipulate the characteristics
associated with a route.
When to Create Routing Policies
Route policies are created in the config>router context. There are no default route
policies. Each route policy must be explicitly created and applied. Applying route policies
can introduce more efficiency as well as more complexity to the capabilities of the 7705 SAR.
Route policies are used to configure which MPLS labels should be learned or advertised.
Based on the configured routing policy, MPLS labels from certain neighbors can be
discarded.
Route policies are also used to control the size and content of the BGP, OSPF, and IS-IS
routing tables, the routes that are advertised, and the best route to take to reach a destination.
Route policies can be created to control:
• a protocol to export all the active routes learned by that protocol
• route characteristics to control which route is selected to act as the active route to
reach a destination and advertise the route to neighbors
• the protocol to import all routes into the routing table. A routing table must learn
about particular routes to be able to forward packets and redistribute to other routing
protocols.
•damping
Before a route policy is applied, analyze the policy’s purpose and be aware of the results (and
consequences) when packets match the specified criteria and the associated actions and
default actions, if specified, are executed. Membership reports can be filtered based on a
specific source address.
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