The Versa Networks Quality of Service (QoS) framework on its CPEs is fundamentally built upon three core functions. First, Classification identifies and categorizes traffic based on various criteria like application, IP address, or DSCP markings. Second, Ingress Policing is applied to rate-limit traffic entering an interface, ensuring it conforms to a specified bandwidth profile by dropping excess packets. Third, Hierarchical Queuing, a key feature of Versa's Hierarchical QoS (H-QoS), manages network congestion at egress by scheduling packets through a multi-level queue structure. This provides granular control over bandwidth allocation and prioritization for different traffic classes, ensuring service level agreements (SLAs) are met.

A. admission control: This is a more specific mechanism, like Call Admission Control (CAC) for VoIP, not a foundational QoS function in the general Versa framework.

C. egress policing: Versa's architecture predominantly uses egress shaping and hierarchical scheduling to manage outbound traffic, while policing is the primary mechanism for rate-limiting at ingress.

1. Versa Networks VOS™ Quality of Service (QoS) Configuration Guide (Release 22.1):

Section: QoS Overview

Page 7: This section outlines the basic QoS workflow

stating

"The basic QoS process is to classify incoming packets and then apply a QoS policy to them... The actions include policing the traffic... and queuing the traffic for transmission." This confirms Classification

Policing

and Queuing as core components.

Section: Hierarchical QoS

Page 10: This section details the H-QoS model

explaining

"Versa VOS supports hierarchical QoS (H-QoS)

which allows you to apply queuing and shaping at multiple levels of a hierarchy." This directly supports Hierarchical Queuing (B).

Section: Configuring Policers

Page 45: This chapter describes the function and configuration of policers

specifying their use for rate-limiting. The examples and context consistently apply policers to input/ingress traffic

supporting Ingress Policing (E).

Section: Configuring Classifiers

Page 29: This chapter details the process of identifying traffic flows based on various fields

which is the definition of Classification (D).