Redirect Policies - Alcatel-Lucent 7450 Configuration Manual

Filter Policy Advanced Topics

Redirect Policies

SROS-based routers support configuring of IPv4 redirect policies. Redirect policies allow
specifying multiple redirect target destinations and defining health check test methods used to
validate the ability for a given destination to receive redirected traffic. This destination monitoring
allows router to react to target destination failures. To specify IPv4 redirect policy, define all
destinations to be IPv4. IPv4 redirect policy can only be deployed in IP filter policies.
Redirect policy supports the following destination tests:
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Each destination is assigned an initial or base priority describing this destination's relative
importance within the policy. The destination with the highest priority value is selected as most-
preferred destination and programmed on line cards in filter policies using this redirect policy as an
action. Note that only destinations that are not disabled by the programmed test (if configured) are
considered when selecting the most-preferred destination.
Feature caveats:
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Router Instance Support for Redirect Policies
There are two modes of deploying redirect policies on VPRN interfaces. The functionality
supported depends on the configuration of redirect-policy router option with
(config>filter>redirect-policy-router):
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ping test – with configurable interval, drop-count, and time-out for the test
url-test – with configurable URL to test, interval, drop-count, timeout, and configurable
action (disable destination, lower or raise priority) based upon return error code
snmp-test – with configurable OID and Community strings, interval, drop-count, timeout
for the test, and configurable action (disable destination, lower or raise priority) based
upon SNMP return value.
unicast-rt-test – unicast routing reachability, supported only when router instance is
configured for a given redirect policy. The test yields true if the route to the specified
destination exists in RTM for the configured router instance.
Operational note: unicast-rt-test will fail when performed in the context of a VPRN
routing instance when the destination is routable only through grt-leak functionality.
ping-test is recommended in such cases.
Redirect policy is supported for ingress IPv4 filter policies only.
Different platforms support different scale for redirect policies. Please contact your local
Alcatel-Lucent representative to ensure the planned deployment does not exceed
recommended scale.
7450 ESS Router Configuration Guide