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Enhancing IP Network Quality of Service Control

Learn about the significance of IP QoS control for network convergence and the importance of standardizing QoS classes and mechanisms for efficient implementation. Discover IP QoS classes attributes and strategies for achieving better QoS in IP networks.

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Enhancing IP Network Quality of Service Control

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  1. Recommendation Y.1541 QoS Classes:A Basis for IP Network QoS Control -- Neal Seitz, Chair SG 13/WP 4 • IP QoS control: key to IP/PSTN network convergence • Y.1541: “Step 1” in achieving QoS enabled IP networks • Quantify user/application needs via standard IP QoS classes • Signal the standardized QoS classes to and among networks • Realize the QoS classes using network QoS mechanisms • Standardize QoS signaling protocols using Y.1541

  2. Importance of IP Network QoS Control VoIP/MM needs are clear, but too demanding for today’s IP • Rec. G.114 -- “Mouth-to-ear” signal transmission time • Rec. G.109 -- Categories of speech transmission quality • Rec. G.1010 -- End-user multimedia QoS categories IP QoS solutions exist, but are not widely implemented • RSVP/intserv -- Controlled load, guaranteed services • DIFFSERV -- EF, AF per hop behaviors (PHBs) • MPLS, MPλS -- Traffic engineering, CoS, QoS, VPNs • Linking user application needs with network QoS mechanisms would advance PSTN/IP convergence

  3. Achieving QoS in IP Networks -- Step 1: Quantify User/Application Needs in IP Terms Relate subjective descriptions of QoS imperfections … • Audio: “staticky, warbley, muffled, clipped” • Video: “blurry, jerky, blocky, busy, blotchy” With measurable IP network/terminal characteristics … • Packet loss, delay, delay variation, error • Signal compression artifacts, capacity limits • Capture results in a limited set of QoS classes … • Categorize the major IP user application needs • Can be communicated among networks via signaling • Can be implemented with existing IP QoS mechanisms

  4. Y.1541 “Mapping” Function  Voice  Video  Data  Call Control Customer-Perceived QoS  Subjective Descriptors  Objective Estimators Voice  Video  Data  Call Control Terminal-to-Terminal QoS (Y.1541)  Speed, Accuracy, Dependability  Service Availability (Future) Terminal Terminal Network QoS Network QoS Network QoS Control Network Control Network Control Network Bearer Network Bearer Network Bearer Network

  5. Table 1/Y.1541 -- IP QoS Class Definitions and Network Performance Objectives

  6. Table 2/Y.1541Guidance for IP QoS Classes

  7. Attributes of the Y.1541 IP Network QoS Classes • Encompass the major IP user application categories • Are relatable to practical IP network QoS mechanisms • Can be achieved in realistic network implementations • Are verifiable at jurisdictional network boundaries (TE/IWF can measure QoS to ensure values are met) • Can support QoS negotiation among networks • Meet the need for a lingua franca to support QoS interworking

  8. Achieving QoS in IP Networks -- Step 2: Signal QoS Classes to/among Networks • Allow the user requesting service to specify QoS class • Allow specification of traffic descriptor (Rec. Y.1221) • Support requests for basic IP transport: QoS, traffic • Allow well-defined apps to be identified ex(im)plicitly • Let user decide whether to take lower QoS or clear call • Implement dynamic QoS control, not static allocation • Support QoS class mapping among diverse networks • Allow QoS choices for call control, availability (future) • Communicate the Y.1541 QoS classes directly

  9. Achieving QoS in IP Networks -- Step 3: Realize QoS Classes via Network Mechanisms A sampling of available QoS control strategies … • Admission control / resource reservation (IETF: RSVP, RSVP-TE, MPLS CR-LDP, ... ) • Priority queuing (IETF: DIFFSERV AF, EF PHBs) • Traffic segregation / routing control (IETF: MPLS-based VPNs) • Protection switching (SG 13: Rec. Y.1720) • Mechanisms should be activated/controlled by signaling Y.1541 QoS classes among networks

  10. IP Network QoS Control:Open Issues and Discussion Topics • IP QoS signaling: requirements, principles, functions • Will networks signal “consumption” of impairment budgets? • Can networks signal commitments to “better” QoS values? • IP network “call” control, availability specifications • QoS interworking among networks ( IP, FR, ATM ...) • IP QoS mechanisms: standardized or proprietary? • Broadcast quality digital video on IP-based networks • Coordinated effort involving several ITU-T SGs, ITU-R, IETF, other stake holders is warranted

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