Dell Force10 S55T S55 Configuration Guide FTOS 8.3.5.3 - Page 582
Pre-calculating Available QoS CAM Space, Available CAM, Estimated CAM
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www.dell.com | support.dell.com For example, if you configure 70% bandwidth to multicast, 80% bandwidth to one queue in unicast and 0 % to all remaining unicast queues, then first, FTOS assigns 70% bandwidth to multicast, then FTOS derives the 80% bandwidth for unicast from the remaining 30% of total bandwidth. Pre-calculating Available QoS CAM Space c e s Pre-calculating Available QoS CAM Space is supported on platforms: Before version 7.3.1 there was no way to measure the number of CAM entries a policy-map would consume (the number of CAM entries that a rule uses is not predictable; 1 to 16 entries might be used per rule depending upon its complexity). Therefore, it was possible to apply to an interface a policy-map that requires more entries than are available. In this case, the system writes as many entries as possible, and then generates an CAM-full error message (Message 1). The partial policy-map configuration might cause unintentional system behavior. Message 1 QoS CAM Region Exceeded %EX2YD:12 %DIFFSERV-2-DSA_QOS_CAM_INSTALL_FAILED: Not enough space in L3 Cam(PolicyQos) for class 2 (Gi 12/20) entries on portpipe 1 for linecard 12 %EX2YD:12 %DIFFSERV-2DSA_QOS_CAM_INSTALL_FAILED: Not enough space in L3 Cam(PolicyQos) for class 5 (Gi 12/22) entries on portpipe 1 for linecard 12 The command test cam-usage enables you to verify that there are enough available CAM entries before applying a policy-map to an interface so that you avoid exceeding the QoS CAM space and partial configurations. This command measures the size of the specified policy-map and compares it to the available CAM space in a partition for a specified port-pipe. Test the policy-map size against the CAM space for a specific port-pipe or all port-pipes using these commands: • test cam-usage service-policy input policy-map {linecard | stack-unit } number port-set number • test cam-usage service-policy input policy-map {linecard | stack-unit } all The output of this command, shown in Figure 31-16, displays: • the estimated number of CAM entries the policy-map will consume • 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 is the available number of CAM entries in the specified CAM partition for the specified line card or stack-unit port-pipe. • Estimated CAM is the estimated number of CAM entries that the policy will consume when it is applied to an interface. 582 | Quality of Service
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