800 Policy configuration overviewN0008589 3.3COPSWhen used with the Optivity Policy Services ® (OPS) Version 1.2 or later, a comprehensivenetwork management application combining IP address management with policy-based networktraffic control, Business Communications Manager effectively manages network traffic andresources. Information is transferred using the Common Open Policy Services (COPS) protocol, aquery and response protocol that exchanges policy information messages using the TransmissionControl Protocol (TCP). Specifically, COPS for Provisioning (COPS-PR) is used to downloadinformation. COPS is used to communicate with edge devices on the network.OPS provides a centralized management point for DiffServ policies. The policy server distributespolicies to edge devices and border routers. These edge devices police traffic flows by markingpackets and applying forwarding behaviors to the packets at the network node.For further information about Optivity products, contact your Nortel Networks salesrepresentative.Policy overviewUse Unified Manager to configure policies and filters to control the behavior of network traffic. Apolicy is a network traffic controlling mechanism that monitors the characteristics of the traffic(for example, its source, destination, and protocol) and performs a controlling action on the trafficwhen certain user-defined characteristics are matched. A policy action is the effect a policy has onnetwork traffic that matches the traffic profile of the policy. You can assign only one action to apolicy. You set up filters to establish packet-specific criteria that determine how a packet is to beprocessed. You can use filters to remark packets by updating the DSCP code points, to changepriorities, or to drop packets.LAN ports on Business Communications Manager are configured according to the policydetermining traffic priorities. As packets enter the switch, they are marked according to theirpriority.After the packets are marked, they are moved to the proper egress queue based on their marking.When a packet is to be transmitted, the switch looks at the Premium queue first. Then BusinessCommunications Manager examines the other queues and sends packets based on the weightedpercentage for the queues. The entire process is repeated. This approach ensures that the Premiumpackets are serviced quickly and that the other data types (other queues) are not starved andserviced in a round-robin fashion.A packet is processed as follows:1 The packet enters Business Communications Manager.2 Filters are applied.3 Filter actions are taken and the packet can be modified (DSCP).4 The packet is assigned a QoS class. A QoS class is designated using the DSCP values.5 The packet is placed in the appropriate egress queue according to its priority marking asdescribed above.6 The queues are serviced in a round-robin fashion (strict priority or weighted fair queueing).
