Dell Force10 C150 - Pre-Calculating Available Qos CAM Space

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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
Pre-calculating Available QoS CAM Space is supported on platforms: c e s
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.
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 41-16, 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.
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-2-
DSA_QOS_CAM_INSTALL_FAILED: Not enough space in L3 Cam(PolicyQos) for class 5 (Gi 12/22)
entries on portpipe 1 for linecard 12