Reference Guide

Quality of Service (QoS) | 681
Pre-calculating Available QoS CAM Space
Pre-calculating Available QoS CAM Space is supported on the platforms: s z
Before FTOS 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). 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
test cam-usage command allows 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 {stack-unit | stack-unit } number port-set number
• test cam-usage service-policy input policy-map {stack-unit | stack-unit } all
The output of this command, shown in Figure 37-11, 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 consumes when it is
applied to an interface.
• Status — indicates whether or not the specified policy-map can be completely applied to an interface
in the port-pipe.
• Allowed — indicates that the policy-map can be applied because the estimated number of CAM
entries is less or equal to the available number of CAM entries. The number of interfaces in the
port-pipe to which the policy-map can be applied is given in parenthesis.
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 (Te 12/20) entries on portpipe 1 for stack-unit 12
%EX2YD:12 %DIFFSERV-2-
DSA_QOS_CAM_INSTALL_FAILED: Not enough space in L3 Cam(PolicyQos) for class 5 (Te 12/22)
entries on portpipe 1 for stack-unit 12