The packets that are destined for 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, and so on The CPU provides 8 (eight) queues from BE (0) to NC (7). The packets destined for 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 bandwidth and priority to them. It is not configurable by the user.