Alcatel-Lucent 7750 SR-OS, Configuration Manual

Page: 418 / 674

ACL Filter Policy Overview
Page 418 7750 SR OS Router Configuration Guide
Redirect Policies
SROS-based routers support redirect policies. Redirection policies are used to identify cache
servers (or other redirection target destinations) and define health check test methods used to
validate the ability for the destination to receive redirected traffic. This destination monitoring
greatly diminishes the likelihood of a destination receiving packets it cannot process.
Redirection identifies packets to be redirected and specifies the method to reach the web cache
server. Packets are identified by IPv4 filter entries. The redirection action is accomplished and
supported with Policy Based Routing. Only IPv4 routed frames can be redirected. Bridged IP
packets that match the entry criteria will not be redirected.
Redirection policies can contain multiple destinations. Each destination is assigned an initial or
base priority describing its relative importance within the policy. The destination with the highest
priority value is selected.
There are no default redirect policies. Each redirect policy must be explicitly configured and
specified in an IPv4 filter entry.
To facilitate redirection based on a redirection policy, an IPv4 filter must be created and applied to
the appropriate ingress IP interfaces where redirection is required. The entry criteria for the filter
entry must specify a redirect policy to enable the appropriate IPv4 packets to be redirected from the
normal IPv4 routing next hop. If packets do not meet any of the defined match criteria, then those
packets are routed normally through the destination-based routing process.
The redirection policy is referenced within the action context for an IPv4 filter entry, binding the
filter entry to the policy and the IPv4 destinations managed by the policy. The policy specifies the
destination IPv4 address where the packets matching the filter entry will be redirected. When the
policy determines the destination for packets matching the filter, the action on the filter entry is
similar to provisioning that destination IPv4 address as an indirect next hop Policy Based Route
(PBR) action.