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Optimizing QoS in Layer 3 Networks

Explore multimedia network support at Layer 3 with in-depth case studies. Enhance your understanding of IP protocols, QoS, and future technologies for seamless multimedia traffic delivery.

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Optimizing QoS in Layer 3 Networks

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  1. CS 414 – Multimedia Systems DesignLecture 21 – Case Studies for Multimedia Network Support (Layer 3) Klara Nahrstedt Spring 2009 CS 414 - Spring 2009

  2. Outline • Multimedia Network Technologies at the Layer 3 • Past/Current technologies: IPv4 • Future technologies: IPv6, IntServ, DiffServ CS 414 - Spring 2009

  3. Internet Multimedia Protocol Stack Media encaps (H.264, MPEG-4) APPLICATION RTSP RSVP RTCP Layer 5 (Session) SIP RTP Layer 4 (Transport) TCP UDP KERNEL Layer 3 (Network) IP Version 4, IP Version 6 AAL3/4 AAL5 Layer 2 (Link/MAC) Ethernet ATM CS 414 - Spring 2009

  4. Layer 3 Internet Services • Internet Protocol (IP) – IP Version 4 • Provides unreliable deliver of datagrams in a point-to-point fashion • Runs on top of any Layer 2 technologies • Supports • IP address of 32 bits • Different types of services (TOS) • Precedence relation • Services such as minimization of delay, maximization of throughput • Multicast • Internet Group Management Protocol for managing groups CS 414 - Spring 2009

  5. New Internet Protocol - IPng • Next Generation IP – IP Version 6 • Supports new features • New addressing and routing • IP Address 128 bits • Large hierarchical addresses, multicast addresses • More options of flow control and security • Real-time flows • End-to-end security • Provider selection • Host mobility • Auto-configuration/auto-reconfiguration • Traffic Classes CS 414 - Spring 2009

  6. IP Packet Headers Version Header Length TOS Total length identification Flag Fragment offset Time to Live (TTL) Protocol Header Checksum IPv4 32-bit Source IP Address 32 bit Destination IP Address Version Traffic Class Flow Label Payload Length Next Header Hop limit IPv6 128-bit Source IP Address 128-bit Destination IP Address CS 414 - Spring 2009

  7. QoS in Layer 3 - Internet Integrated Services • To provide network QoS in the Internet, IETF reacted by • Creating Working Group (IntServ) • Deploying Internet Integrated Services • Development of Control (Establishment) Protocol to reserve resources per flow • Resource Reservation Protocol (RSVP) • Development of QoS-aware network services within IP • Guaranteed class-of-service • Deterministic QoS guarantees • Controlled-load class-of-service • Statistical QoS guarantees CS 414 - Spring 2009

  8. Integrated Services (IntServ) Architecture Reservation Protocol (RSVP) End-system Router Control Plane Policy control Policy control RSVP daemon RSVP daemon Appl. Routing. Admission control Admission control Packet scheduler Packet classification Packet scheduler Error Handling Data Plane CS 414 - Spring 2009

  9. RSVP • Provides reservation for data flows • Flow specification is represented via • Traffic specification, TSpec • Characteristics of the data flow • Request specification, Rspec • Description of required QoS (desired flow behavior) • Is receiver-oriented and unidirectional • Uses two types of messages: • PATH messages and RSVP messages • Protocol • Send PATH message with TSpec from Sender to Receiver(s) • Send RESV message with Rspec from Receiver(s) to Sender • Send DATA with resulting reserved QoS CS 414 - Spring 2009

  10. RSVP Control and Data Flow (1) TSpec (1) TSpec (3) (1) D1 S1 (3) (3) R1 R2 (2) TSpec,RSpec (2) Tspec,RSpec (2) (3) (2) (1) (2) Tspec,RSpec R4 R3 (3) D2 D3 (1) TSpec RESV messages DATA PATH messages CS 414 - Spring 2009

  11. Mixing Reservations 15MB 15MB Mixing Mixing D1 S1 R1 R2 10MB 12MB 10MB 3MB 12MB 15MB 3MB R4 R3 D2 D3 12MB 15MB RESV messages DATA PATH messages CS 414 - Spring 2009

  12. Reservation Structures Version Flags Message Type RSVP Checksum Send TTL Reserved RSVP Length • Resource Reservation Table • Stores admitted/reserved resources • RSVP Messages CS 414 - Spring 2009

  13. RSVP Features • Simplex Reservation • Reservation only in one direction (simplex flow) • Receiver Oriented • Supports multicast communication • Routing Independent • Policy Independent • Soft State • Reservation state has timer associated with the state • When timer expires, state is automatically deleted • RSVP periodically refreshes reservation state to maintain state along the path CS 414 - Spring 2009

  14. Reservation Styles (1) • Wild-card Filter Style • WF implies shared reservation and wild-card sender selection • All receivers share a single reservation whose size is the largest of the resource requests from the receivers • All upstream senders can use the reservation • WF(*,{Q}), where • * represents wild-card sender selection • {Q} represents Flow Spec. CS 414 - Spring 2009

  15. Reservation Styles (2) • Fixed-filter (FF) style • FF implies distinct reservation and explicit sender selection • Distinct reservation is established for specific sender • FF(S1(Q1), S2(Q2), … Sn(Qn)), where • S1, ..Sn are senders • Q1,…,Qn are corresponding flow specs CS 414 - Spring 2009

  16. Reservation Styles (3) • Shared explicit (SE) style (Dynamic filter) • SE implies shared reservation but explicit sender selection • SE creates a single reservation shared by specific senders • Receiver can explicitly list what senders are to be included in reservation • SE((S1,..,Sn){Q}), where • S1,…,Sn are senders • Q corresponding flow spec CS 414 - Spring 2009

  17. Service Models • Describe interface between network and its users in resource allocation architecture • Describe what services users can ask from network and what kind of resource commitments the network can offer • IntServ standard • Guaranteed Service • Controlled-load Service CS 414 - Spring 2009

  18. Flow Specification (1)(Traffic Shape General Parameters) Peak rate – highest rate at which a source can generate traffic Average rate – average transmission rate over a time interval Burst size – max amount of data that can be injected into network at peak rate CS 414 - Spring 2009

  19. Flow Specification (2)(in IntServ) • Traffic described in terms of token bucket parameters • Token arrival rate ‘r’ • Bucket depth ‘b’ • Amount of bits transmitted during any interval of length t: A(t) ≤ r * t + b CS 414 - Spring 2009

  20. Service Requirements (Application-specific) • Minimum Bandwidth - min. amount of BW required by application • Delay – can be specified as average delay or worst case delay • Propagation delay + Transmission delay + Queuing delay • Delay Jitter – specifies max. difference between the largest and smallest delays that packets experience • Loss Rate – ratio of lost packets and total packets transmitted CS 414 - Spring 2009

  21. Conclusion • IntServ over Link Layers • IETF created Integrated Services over Specific Link Layers (ISSLL) • Keep in mind that one needs to do • Service mapping • Setup protocol mappings CS 414 - Spring 2009

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