QoS Protocol Description

Overview

This article describes the approach, methods, and configuration details for realizing Quality of Service (QoS) attributes for Ethernet Services.

The traffic criteria requirements are realized by the following QoS functionalities: -

• Traffic classification - The ingress traffic at the UNI Port might first be classified into several traffic flows via the traffic classification. Based on the criticality of the subscriber or traffic services over others. For each classified traffic flow, marking, egress queue assignment, and Ingress policing or metering shall be applied.
• Policing (or Metering) - Determines the guaranteed performance traffic which must be delivered, which must be delivered in best-effort, and which must be dropped.
• Marking - Service prioritization is achieved using priority markings
• Queuing - Mapping of traffic services to the egress queue in the egress port.

Traffic Classification

Quality of Service (QoS) attributes are distinguished and assigned to Ethernet Services, for the traffic flow classified based on the following:

• UNI Port
• EVC (based on UNI Port + C-VLAN)
• UNI Port + C-VLAN + C-VLAN 802.1p Priority
• UNI Port + 802.1p

L2 ACL shall be used to classify the traffic for the above criteria.

Metering (or Policer)

The process of measuring the rate of a traffic stream selected by a Traffic classification or classifier like ACL. The instantaneous state of this process may be used to mark or drop, and/or may be used for accounting and measurement purposes.

Metering defines an entry that has a metering index and rates. And the action to specify the attributes.

Metering Statistics

Every meter entry is enabled to count the statistics associated with it. Using the metering entry ID, the following statistics are computed:

1. Conformed Packets
2. Exceed Packets
3. Violated Packets

Queuing and Remarking

Queue Map Table configuration is used to egress queue id for the traffic been classified. Entry created with Queue Map configuration is associated with Policy Map, to assign the egress queue id of the traffic classified with traffic classifier (ACL and CLASS).

Policy Map has the configuration to specify the remarking priority of the traffic classified.

Data Flow of Ethernet Services and QoS

This section describes details of the data flow of Ethernet Services and its QoS attributes association.

1. EVC Mapping entries for VLAN Tag Manipulation (identifying S-VLAN) are created with Provide Bridge CVID Registration CLI commands.
2. Traffic Classification shall be done with the ACL mechanism.
3. Each traffic flow is associated with the Metering Table entries.
4. Metering entries are separate Policer Tables entries in Marvell, each containing traffic policing attributes like meter type, CIR, CBS, EIR, and EBS.
   

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   Note: CIR & EIR configuration in ISS configurations are in units of kbps. CBS and EBS configurations are in units of bytes.

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5. Each metering action is done using QoS Profile entries. Metering action shall either be priority remarking, with queuing on a one-to-one basis, or drop for exceed and violate actions.
6. In the scenarios without Policer, Policy Map and Queue Map configurations are used for priority remarking and queuing.