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Introduction to QoS2 and qWAVE

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QoS2 is a suite of Quality of Service APIs introduced with Windows Vista and Windows Server 2008. It provides differentiated services for "on-link" (single IP subnet) and "off-link" (multiple IP subnet) scenarios on a per-socket basis.

Specifically, off-link scenarios allow a QoS2 caller to perform the following actions, without any form of admission control:

  • DSCP marking (packet prioritization)
  • Packet send rate limitation (throttling)

On-link scenarios target home networks which have a single subnet defined for them. The QoS subsystem that enables on-link scenarios is called Quality Windows Audio/Video Experience (qWAVE). qWAVE provides several new technologies focused on streaming multimedia and real-time content over works variable bandwidth home networks (such as Wi-Fi enabled local networks). These technologies include:

  • Auto-discovery of end-to-end discovery of QoS capability
  • End-to-end bandwidth estimation of:
    • Maximum link capacity (bottleneck bandwidth)
    • Real-time bandwidth availability metrics
  • Intelligent packet prioritization
  • Congestion and congestion relief notifications
  • Send rate limiting (throttling)
  • Distributed admission control

For the specific QoS2 and qWAVE APIs, please refer to the qWAVE API Reference.