ITUT Recs. Y.1541 and Y.1221 A Basis for IP Network QoS Control and Traffic Management

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ITU-T Recs. Y.1541 and Y.1221 A Basis for IP
Network QoS Controland Traffic Management

• Neal Seitz
• U.S. Department of Commerce, NTIA/ITS

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Y.1541 / Y.1221 Roles

• 3 Steps in achieving IP network QoS control
• Quantify user/application QoS needs
• (and associated traffic characteristics)
• Communicate the QoS needs and traffic
  characteristics into and among networks
• Implement IP network QoS mechanisms supporting
  the requested QoS/traffic levels
• Y.1541 QoS classes quantify user application
  needs in terms of IP network performance
• Y.1221 traffic contract complements QoS class
  by describing flow characteristics/limits

• The two Recommendations together specify the
  key data for IP network QoS signalling.

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Y.1541 Quantifying User QoS Needs in IP Terms

• Relate subjective QoS descriptions
• Audio staticky, warbley, muffled, clipped
• Video blurry, jerky, blocky, busy, blotchy
• With IP network/terminal attributes
• Packet transfer delay, delay variation
• Packet loss and error ratios
• Capture results in a set of QoS classes that
• Categorize major IP user application needs
• Can be communicated via signaling
• Can be supported with IP QoS mechanisms.

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Y.1541 Mapping Function
Terminal
Terminal
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Table 1/Y.1541 -- IP QoS Class Definitions and NP
Objectives
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Table 2/Y.1541Guidance for IP QoS Classes
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Attributes of the Y.1541 IP Network QoS Classes

• Encompass major IP application categories
• Are relatable to IP network QoS mechanisms
• Are achievable in realistic implementations
• Are verifiable at jurisdictional boundaries
• (TE/IWF can measure QoS, ensure values met)
• Can support QoS negotiation among systems

• Meet need for a lingua franca to support
• QoS interworking

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Y.1221 Traffic and Congestion Control in IP
Based Networks

• Traffic Contract defines conditions under which
  specified QoS levels can be met.

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Possible Relationships Between Y.1541 Classes and
Y.1221 TCs(for the Diffserv QoS Mechanism)
A modified DBW capability could also be used.
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Signaling QoS/Flow Requests SG 13 Proposed
Requirements

• Allow requesting user to specify QoS class
• Allow user specification of traffic descriptor
• Allow ex(im)plicit definition of common apps
• Support basic IP packet transport QoS, traffic
• Let user decide to take lower QoS or clear call
• Implement dynamic (not static) QoS allocation
• Support QoS mapping among diverse networks
• Allow QoS choices for call control, availability
  (future)

• Signal Y.1541, Y.1221 values ex(im)plicitly

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Example QoS Signaling Exchange
Terminal
Terminal
Control Network
Control Network
Control Network
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Example QoS Signaling Exchange
Terminal
Terminal
Control Network
Control Network
Control Network
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QoS Signaling Completed-- Flow Established
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Figure 1/Y.qosar Architectural Framework for
QoS Support
Management Plane
Policy
Control Plane
Data Plane
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Figure 2/Y.qosar A Comprehensive QoS Approach
Based on Resource Isolation and Service Requests
(Under Study)
Service Control Layer
Bearer Control Layer
Bearer Layer
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Synopsis and Next Steps

• Synopsis
• Signaling QoS (and flow) parameters will be
  essential to successful IP/PSTN convergence
• Y.1541 QoS classes, Y.1221 traffic contracts
  define the essential content to be signalled
• Next Steps for Standards Organizations
• Complete/coordinate signalling requirements
• Implement requirements in specific protocols
• Develop QoS signalling interworking solution

• Coordinated effort involving ITU-T, ITU-R,
  IETF, and other stakeholders is warranted