Cisco Systems OL-4387-02 manual SSG Hierarchical Policing Overview

C H A P T E R 8

SSG Hierarchical Policing

The SSG Hierarchical Policing feature ensures that a subscriber does not utilize additional bandwidth for overall service or for a specific service that is outside the bounds of the subscriber’s contract with the service provider.

This chapter describes the SSG Hierarchical Policing feature supported by the Cisco 10000 series router.

SSG Hierarchical Policing Overview

The traffic policing feature limits the transmission rate of traffic entering or leaving a node. In SSG, traffic policing can be used to allocate bandwidth between subscribers and between services to a particular subscriber to ensure all types of services are allocated a proper amount of bandwidth. SSG uses per-user and per-service policing to ensure bandwidth is distributed properly between subscribers (per-user policing) and between services to a particular subscriber (per-session policing). Because these policing techniques are hierarchical in nature (bandwidth can be first policed between users and then policed again between services to a particular user), the feature is called SSG Hierarchical Policing.

Per-user policing is used to police the aggregated traffic destined to or sent from a particular subscriber and can only police the bandwidth allocated to a subscriber. Per-user policing cannot identify services to a particular subscriber and police bandwidth between these services.

Per-session policing is used to police the types of services available to a subscriber. Per-session policing is useful when an SSG subscriber is subscribed to multiple services and the services are allocated different amounts of bandwidth. For example, a subscriber pays separately for Internet access and video service but receives both services from the same service provider. The video service would likely be allocated more bandwidth than the Internet access service and would likely cost more to the subscriber. Per-session policing provides a mechanism for identifying the types of services (such as the video service or Internet access in the example) and ensuring that users do not exceed the allocated bandwidth for the service.

SSG Hierarchical Policing Token Bucket Scheme

The SSG Hierarchical Policing token bucket scheme uses an algorithm to police the use of bandwidth. The parameters that the algorithm uses to allocate bandwidth are user-configurable; however, other unpredictable variables (such as time between packets and packet sizes) ultimately determine whether a packet is transmitted or dropped.

For more information, refer to the Service Selection Gateway Hierarchical Policing, Release 12.2(4)B feature module.

Cisco 10000 Series Router Service Selection Gateway Configuration Guide

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