The normal handling of SAP ingress access packets applies an in-profile or out-of-profile state (associated with the colors green and yellow, respectively) to each packet relative to the dynamic rate of the queue while the packet is forwarded toward the egress side of the system. When the queue rate is within or equal to the configured CIR, the packet is considered in-profile. When the queue rate is above the CIR, the packet is considered out-of-profile (this applies when the packet is scheduled out of the queue, not when the packet is buffered into the queue).
Egress queues use the profile marking of packets to preferentially buffer in-profile packets during congestion events. When a packet has been marked in-profile or out-of-profile by the ingress access SLA enforcement, the packet is tagged with an in-profile or out-of-profile marking allowing congestion management in subsequent hops toward the packet’s ultimate destination. Each hop to the destination must have an ingress table that determines the in-profile or out-of-profile nature of a packet, based on its QoS markings.
Color aware profiling adds the ability to selectively treat packets received on a SAP as in-profile or out-of-profile regardless of the queue forwarding rate. This allows a customer or access device to color a packet out-of-profile with the intention of preserving in-profile bandwidth for higher priority packets. The customer or access device may also color the packet in-profile, but this is rarely done as the original packets are usually already marked with the in-profile marking.
Each ingress access forwarding class may have one or multiple subclass associations for SAP ingress classification purposes. Each subclass retains the chassis-wide behavior defined to the parent class while providing expanded ingress QoS classification actions. Subclasses are created to provide a match association that enforces actions different than the parent forwarding class. These actions include explicit ingress remarking decisions and color aware functions.
All non-profiled and profiled packets are forwarded through the same ingress access queue to prevent out-of-sequence forwarding. Profiled packets in-profile are counted against the total packets flowing through the queue that are marked in-profile. This reduces the amount of CIR available to non-profiled packets causing fewer to be marked in-profile. Profiled packets out-of-profile are not counted against the total packets flowing through the queue that are marked in-profile. This ensures that the amount of non-profiled packets marked in-profile is not affected by the profiled out-of-profile packet rate.