• Whether or not the policy-map can be applied.• The number of interfaces in a port-pipe to which the policy-map can be applied.Specifically:• Available CAM — the available number of CAM entries in the specified CAM partition for the specifiedline card or stack-unit port-pipe.• Estimated CAM — the estimated number of CAM entries that the policy will consume when it isapplied to an interface.• Status — indicates whether the specified policy-map can be completely applied to an interface in theport-pipe.– Allowed — indicates that the policy-map can be applied because the estimated number of CAMentries is less or equal to the available number of CAM entries. The number of interfaces in theport-pipe to which the policy-map can be applied is given in parentheses.– Exception — indicates that the number of CAM entries required to write the policy-map to theCAM is greater than the number of available CAM entries, and therefore the policy-map cannot beapplied to an interface in the specified port-pipe.NOTE: The show cam-usage command provides much of the same information as the test cam-usage command, but whether a policy-map can be successfully applied to an interface cannot bedetermined without first measuring how many CAM entries the policy-map would consume; thetest cam-usage command is useful because it provides this measurement.• Verify that there are enough available CAM entries.test cam-usageExample of the test cam-usage CommandDell# test cam-usage service-policy input pmap_l2 port-set 0Port-pipe | CAM Partition | Available CAM | Estimated CAM | Status=============================================================================0 L2ACL 500 200 Allowed(2)Configuring Weights and ECN for WREDThe feature to configure a weight for WRED and ECN functionality for backplane ports is supported onthe S6000 platform.The WRED congestion avoidance functionality drops packets to prevent buffering resources from beingconsumed. Traffic is a mixture of various kinds of packets. The rate at which some types of packets arrivemight be greater than others. In this case, the space on the buffer and traffic manager (BTM) (ingress oregress) can be consumed by only one or few types of traffic, leaving no space for other types. You canapply a WRED profile to a policy-map so that the specified traffic can be prevented from consuming toomuch of the BTM resources.WRED drops packets when the average queue length exceeds the configured threshold value to signifycongestion. ECN is a capability that enhances WRED by marking the packets instead of causing WRED todrop them when the threshold value is exceeded. If you configure ECN for WRED, devices employ ECNto mark the packets and reduce the rate of sending packets in a congested network.In a best-effort network topology, data packets are transmitted in a manner in which latency orthroughput is not maintained to be at an effective level. Packets are dropped when the networkQuality of Service (QoS) 663
