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QoS

2. Introduction. QoS is one of the biggest issueA free servicePaying subscribersService packageLower cost than the PSTNVoice and data serviceTechnical solutions for providing QoSVarious solutionsCombined to complement each other. 3. The Need for QoS. A collective measure of the level of ser

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QoS

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    1. QoS Chapter 8

    2. 2 Introduction QoS is one of the biggest issue A free service Paying subscribers Service package Lower cost than the PSTN Voice and data service Technical solutions for providing QoS Various solutions Combined to complement each other

    3. 3 The Need for QoS A collective measure of the level of service For a particular application Performance criteria Availability, throughput, connection setup time, percentage of successful transmissions, speed of fault detection and correction Bandwidth, packet loss, delay and jitter IP is a best-effort service Well suited to non-real-time communication TCP Error-free, in-sequence delivery delay

    4. 4 UDP Fine for transporting voice Provided that Low packet loss Little congestion on the network Traffic in the network can be bursty and unpredictable A speaker may be forced to repeat what he just said In case of significant packet loss To attract and retain paying subscribers Circuit switching has a distinct advantage But ill-suited to other forms of communication IP network: solutions for the QoS are needed Resource-reservation techniques

    5. 5 End-to-End QoS QoS must be end-to-end The support of all networks in the chain SLAs Service-Level Agreements between different operators Regarding the type and quality of service to be offered Or the penalties VoIP and voice over the Internet Are not the same SLAs may be possible between certain VoIP carriers

    6. 6 Things will get better VoIP for long-distance service Connected to the PSTN at each end Some VoIP operators Begin on IP and terminate on the PSTN More VoIP operators Over IP from source to destination All of the providers embrace the same quality objectives and implement similar technical solutions Voice over the Internet?

    7. 7 It’s not just the network A quality service A lot more than just good voice quality A potentially high cost associated with acquiring a customer Means Superior customer service, rapid service provisioning, 100 percent accurate billing, clear and concise product descriptions, etc.

    8. 8 Overview of QoS Solutions One approach Reserve the resource before establishing the session Has certain similarities to circuit switching Another approach Categorize traffic into different classes or priorities Real-time applications with higher-priority values Require a fair resource-allocation techniques The easiest technique The provision of more bandwidth

    9. 9 More Bandwidth Sounds like a simplistic and expensive No major system development Significant overbuild Unused for most of the time An inefficient way Huge advances in bandwidth 9600-baud modem 56kbps modem DSL The core of the network, DWDM

    10. 10 Moore’s Law Doubles roughly every 18 months Bandwidth availability and bandwidth demand have tended to move almost in lock-step New applications to use the available bandwidth

    11. 11 QoS Protocols and Architectures RSVP, Resource-Reservation Protocol RFC 2205 Part of the IETF integrated-services suite Enable resources to be reserved for a given session in prior The most complex, and closest to circuit emulation Strong QoS guarantees Significant granularity of resource allocation Significant feedback to applications Two levels of service Guaranteed - as close as possible to circuit emulation Controlled load – equivalent to the service in a best-effort network under no-load conditions

    12. 12 RSVP

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