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End-to-End QoS Control in H.323 Networks

This paper discusses the control of quality of service (QoS) in H.323 networks, focusing on factors such as packet loss, jitter, and overall delay. It examines both a conventional approach to delivering QoS and an application-controlled approach, highlighting the advantages of the latter. The concept of QoS budgets and mapping QoS to H.323 signals is also explored. The paper concludes with an overview of the new H.323 protocols being developed to support end-to-end QoS control.

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End-to-End QoS Control in H.323 Networks

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  1. End to End Quality of Service Control in H.323 Networks Mike BuckleyLucent Technologies

  2. Overall Packet Loss Codec Performance Perceived Quality Jitter Buffers Overall Delay QoS Service Level Inter-relationship of QoS Factors Network Packet Loss Network Jitter Network Delay • Application Factors • Network Factors

  3. QoS Parameters QoS Service Class SERVICE Codec, Frames per Packet, Frame Size, Jitter Buffer Size, Overall Delay, Overall Packet Loss, FEC (Redundancy) APPLICATION Network Packet Loss, Mean Delay, Delay Variation TRANSPORT

  4. End User Domain Service Domain Service Domain Service Domain Service Domain End User Domain Service Domain Administrative Domains Transport Network

  5. End User Domain Service Domain Service Domain Service Domain Service Domain End User Domain Service Domain Transport Domain Transport Domain Transport Domain Domains - Managed Networks

  6. Conventional Approach to Delivering QoS End-to-end

  7. H.225.0, H.245 H.225.0, H.245 H.225.0, H.245 RSVP, DiffServ RSVP, DiffServ UDP/IP UDP/IP RSVP, DiffServ RSVP, DiffServ UDP/IP UDP/IP Packet Flow Service Domain 1 Transport Domain 1 Transport Domain 2 Transport Domain 3 QoS Signalling H.323 Signalling The End-to-end (Internet) QoS Model Application Plane Transport Plane

  8. H.323 End-to-end QoS Support • H.323 Appendix 1 Allows for: • End Points to indicate ability to support RSVP prior to call set-up, • synchronization of QoS capability signalling with RSVP signalling between end points at call set-up.

  9. Problems with this Approach • BUT • Transport domains may support different QoS mechanisms and policies. • Who owns the end to end picture? • No mechanism to select transport domain on basis of QoS levels supported. c.f choice of alternative long distance carriers. • QoS messages are not signalled to the service provider - how can he control the QoS levels offered? • Need a business model for supplying and charging for QoS

  10. H.323 signalling to support the above Current Work - Imperatives • NEED • A new approach. • An end to end QoS architecture. • Domain by domain control. • A model that allows and supports charging for QoS.

  11. Application Controlled Approach to Delivering QoS End-to-end

  12. Service Domain 1 Transport Domain 1 Transport Domain 2 Transport Domain 3 An Application Controlled Approach to QoS Application Plane Transport Plane Packet Flow QoS Signalling Call Signalling

  13. Advantages of the Application Controlled Approach to End-to-end QoS CLEAR BUSINESS MODEL • The Application Service Provider is in the driving seat. End-to-end (inter-domain) QoS control takes place within the Application Plane. (Between Service Providers) • Required end-to-end QoS levels are established within the Application Plane (Between the End User and Service Provider) • Transport Domains (Operators) provide a QoS service to the associated Service Domains (Service Providers). QoS controlwithin a Transport Domain is the responsibility of the Operator of that domain

  14. Advantages of the Application Controlled Appoach to End-to-end QoS (Cont) OTHER ADVANTAGES • A common interface can be defined between a Transport Domain and its associated Service Domain even though different QoS mechanisms may be present within the Transport Plane • No QoS information need be exchanged between the End User and Network Operator or between Network Operators • Application Controlled Firewalls and NATS can be accommodated

  15. Service Domain 1 Service Domain 2 Mixed Transport QoS Mechanisms Application Plane Transport Plane Transport Domain 4 (RSVP) Transport Domain 1 (RSVP) Transport Domain 2 (Diff Serv) Transport Domain 3 (MPLS/ATM) Media Flow QoS Signalling Call Signalling

  16. The Concept of QoS Budgets

  17. Mapping QoS to H.323 Signals

  18. QoSPE End UserDomain ServiceDomain Terminal GK Protocols Involved QoSPE ServiceDomain GK H.323 H.323 H.qos H.qos H.qos Application Plane Transport Plane End User Transport Domain Transport Domain Transport Domain QoS Signalling Packet Flow

  19. New Annex N of H.323 Additions to H.323 Protocols • QoS is determined on a per media stream basis so QoS is negotiated per media stream via H.245. New fields in H.245 under development. • QoS Class may be requested by End User via H.245 or H.225.0. Additions to both protocols under development to enable this. • QoS characteristics of terminals may be registered with service providers. This involves additions to H.225.0 RAS.

  20. New Vertical Protocol Required (H.qos) • Used to signal QoS parameters (max delay, max jitter, max packet loss) to each domain • Typically will be between GK or Media Gateway Controller and Edge Router or Transport Resource Manager • Candidates H.248/Megaco, COPS or possibly RSVP

  21. Summary • End to end signalling of RSVP support by terminals is already provided for in H.323 • New domain by domain QoS approach under development along lines of TIPHON model • New H.323 Annex N will include this functionality • New protocol H.qos will be required to implement domain by domain control.

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