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This section describes the QoS regulator.
The CCN-502 supports end-to-end Quality-of-Service (QoS) guarantees using QoS mechanisms distributed throughout the system. The QoS provision uses the QoS field in each RN request packet to influence arbitration priority at every QoS decision point. The QoS field is then propagated through all secondary packets issued by a request packet. RNs must either self-modulate their QoS priority depending on how well their respective QoS requirements are being met, or make use of the integrated QoS regulators at ingress points to the CCN-502.
It is possible to include non-QoS-aware devices in the system, but still have these devices meet the QoS modulation requirement of the QoS architecture. To enable this, the CCN-502 includes inline regulators that perform the QoS functionality without the requesting device requiring any awareness of QoS. A QoS Regulator (QR) provides an interstitial layer between an RN and the interconnect. The QR monitors how the bandwidth and latency requirements of the RN are met, and does in-line replacement of the RN-provided QoS field, adjusting upwards to gain additional priority in the system, and downwards to reduce priority.