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Chapter 6: Routing Policy Configuration Guide
SSR User Reference Manual 6 - 15
Configure Advanced Routing Policies
Advanced Routing Policies are used for creating complex import/export policies that
cannot be done using the redistribute command. Advanced export policies provide
granular control over the targets where the routes are exported, the source of the
exported routes, and the individual routes which are exported. It provides the
capability to send different routes to the various route-peers. They can be used to
provide the same route with different attributes to the various route-peers.
Import policies control the importation of routes from routing protocols and their
installation in the routing database (Routing Information Base and Forwarding
Information Base). Import policies determine which routes received from other
systems are used by the SSR routing process. Using import policies, it is possible to
ignore route updates from an unreliable peer and give better preference to routes
learned from a trusted peer.
Export Policies
Advanced export policies can be constructed from one or more of the following
building blocks:
• Export Destinations - This component specifies the destination where the routes are
to be exported. It also specifies the attributes associated with the exported routes.
The interface, gateway or the autonomous system to which the routes are to be
redistributed are a few examples of export-destinations. The metric, type, tag, and
AS-Path are a few examples of attributes associated with the exported routes.
• Export Sources - This component specifies the source of the exported routes. It can
also specify the metric to be associated with the routes exported from this source.
The routes to be exported can be identified by their associated attributes, such as
protocol type, interface or the gateway from which the route was received, and so on.
• Route Filter - This component provides the means to define a filter for the routes to
be distributed. Routes that match a filter are considered as eligible for redistribution.
This can be done using one of two methods:
• Creating a route-filter and associating an identifier with it. A route-filter has sev-
eral network specifications associated with it. Every route is checked against the
set of network specifications associated with all route-filters to determine its eli-
gibility for redistribution. The identifier associated with a route-filter is used in the
ip-router policy export command.
• Specifying the networks as needed in the ip-router policy export command.
If you want to create a complex route-filter, and you intend to use that route-filter in
several export policies, then the first method is recommended. It you do not have