One of the processes that make up the ExtremeXOS system is the policy manager. The policy manager is responsible for maintaining a set of policy statements in a policy database and communicating these policy statements to the applications that request them.
Policies are used by the routing protocol applications to control the advertisement, reception, and use of routing information by the switch. Using policies, a set of routes can be selectively permitted (or denied) based on their attributes, for advertisements in the routing domain. The routing protocol application can also modify the attributes of the routing information, based on the policy statements.
Policies are also used by the ACL (Access Control List) application to perform packet filtering and forwarding decisions on packets. The ACL application will program these policies into the packet filtering hardware on the switch. Packets can be dropped, forwarded, moved to a different QoS (Quality of Service) profile, or counted, based on the policy statements provided by the policy manager.