Cpu Queues - Alcatel-Lucent 7210 SAS M OS Quality Of Service Manual

QoS Overview

CPU Queues

The packets that are destined to the CPU are prioritized based on the application. Some of the
applications that are prioritized are Layer 2 data packets (a copy of which is sent to CPU for MAC
learning), EFM, CFM, STP, LACP, ICMP, etc. The CPU provides eight queues from BE (0) to NC
(7). The packets destined to the CPU are classified internally and are put into the correct queue.
These packets are rate-limited to prevent DoS attacks. The software programs the classification
entries to identify these packets and assigns appropriate bandwdith and priority to them. It is not
configurable by the user.
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strict priority queues is serviced first in the order of their CoS numbering (higher
numbered CoS queue receives service before smaller numbered queues). In this mode, the
scheduler services the strict queues first and then the queues configured with weights in
both the CIR and PIR loop. The scheduler ensures that it meets the CIR of all the queues
(both strict queues and queues with weight), if bandwidth is available before scheduling
the queues in the PIR loop. If multiple queues are configured as strict, the higher-priority
strict queues are serviced first before the lower priority strict queues in both the CIR and
the PIR loop. The weights configured for the queues are only considered during the PIR
loop.
7210 SAS M OS Quality of Service Guide