Which of the following statements is a characteristic of a CFHP arbiter?

A Class Fair Hierarchical Policing (CFHP) arbiter is a logical entity within a hierarchical QoS structure whose primary function is to manage and distribute bandwidth among its children. These children can be either policers or other arbiters. The arbiter is configured with its own rate limit and uses a weighting system to fairly allocate its available bandwidth to its children based on their demand. This dynamic allocation process effectively adjusts the bandwidth assigned to each child, ensuring that the collective traffic conforms to the arbiter's rate while maintaining fairness among the subordinate elements.

A. An arbiter does not modify the configured Committed Information Rate (CIR) of its child policers. The CIR is a static configuration on the policer; the arbiter only allocates available bandwidth.
B. An arbiter operates within a logical QoS policy hierarchy. It does not directly rate-limit traffic towards a specific physical hardware component like an egress Forwarding Plane Processor Complex (FFPC).
D. An arbiter must honor the configurations of its child policers. It uses the child's CIR for guaranteed bandwidth allocation and its Peak Information Rate (PIR) as the absolute maximum limit.

1. Nokia 7750 SR OS Quality of Service Guide, Release 21.10.R1, Section: "Hierarchical Policing".

Reference for Correct Answer (C): In the "Class Fair Hierarchical Policing" subsection, it states, "An arbiter is a logical function that is parent to a number of children policers or children arbiters. Its main purpose is to arbitrate the offered load from its children and its own rate limit to determine the amount of bandwidth it can give to each child." This confirms its role in assigning bandwidth.

Reference for Incorrect Answer (A & D): The same section describes the two-pass mechanism where the arbiter first satisfies the CIR of its children and then distributes excess bandwidth fairly up to their PIR. This shows the arbiter honors and works within the child's configured parameters, not adjusts them.

Reference for Incorrect Answer (B): The guide describes CFHP as a function applied at a Service Access Point (SAP), typically on ingress, as part of a logical QoS policy, not as a hardware-specific egress rate-limiter.