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CS 414 – Multimedia Systems Design Lecture 22 – Multimedia Extensions to Existing IP Protocols

CS 414 – Multimedia Systems Design Lecture 22 – Multimedia Extensions to Existing IP Protocols . Klara Nahrstedt Spring 2011. Outline . Multimedia IP Extensions (Layer 3). Internet Multimedia Protocol Stack. Media encaps (H.264, MPEG-4). APPLICATION. RTSP. RSVP. RTCP. Layer 5

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CS 414 – Multimedia Systems Design Lecture 22 – Multimedia Extensions to Existing IP Protocols

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  1. CS 414 – Multimedia Systems DesignLecture 22 – Multimedia Extensions to Existing IP Protocols Klara Nahrstedt Spring 2011 CS 414 - Spring 2011

  2. Outline • Multimedia IP Extensions (Layer 3) CS 414 - Spring 2011

  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 DCCP KERNEL Layer 3 (Network) IP Version 4, IP Version 6 AAL3/4 AAL5 MPLS Layer 2 (Link/MAC) Ethernet/WiFi ATM/Fiber Optics CS 414 - Spring 2011

  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 2011

  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 2011

  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 2011

  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 2011

  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 2011

  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. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  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. Guaranteed Service(in IntServ) • Provides guaranteed BW and strict bounds on end-to-end queuing delay for conforming flows • Controls max. queuing delay • TSpec – describes traffic sources • Bucket rate (‘r’) (bytes/second) • Peak rate (p) (bytes/second) • Bucket depth (b) (bytes) • Minimum policed unit (m) (bytes) – any packet with size smaller than m will be counted as m bytes • Maximum packet size (M) (bytes) – max, packet size that can be accepted CS 414 - Spring 2010

  19. Guaranteed Service (2) • Rspec • Service rate (R) (bytes/second) – service rate or BW requirement • Slack term (S) (µsec) – extra amount of delay that a node may add that still meets the EED (end-to-end delay) requirement. • This service does policing and shaping • Resources are reserved at worst case • For bursty traffic sources – low network utilization CS 414 - Spring 2010

  20. Controlled Load Service(in IntServ) • No quantitative guarantees on delay bound or BW • This service model allows statistical multiplexing – statistical guarantees • Very high % of transmitted packets will be successfully delivered • Transit queuing delay experienced by a very high % of delivered packets will not greatly exceed min. delay • Invocation and Policing • Specify TSpec (average values) and do admission, reservation, policing based on average TSpec CS 414 - Spring 2010

  21. IntServ (Error Handling - Early Congestion Avoidance) Avr – Average Queue Length MaxThres – Max Queue Length Threshold MinThres – Min. Queue Length Threshold Packet Scheduler IP packet IP packet IP packet IP packet IP packet IP packet Input Queue CS 414 - Spring 2010

  22. IntServ (Error Handling) Discard Algorithms • RED: Random Early Detection • single FIFO queue is maintained for all packets and packets are dropped randomly with a given probability when the average queue length exceeds minimum threshold (MinThresh).If max. threshold (MaxThres) is exceeded, all packets are dropped • WRED – Weighted RED • Drops packets selectively based on IP precedence CS 414 - Spring 2010

  23. Incoming IP packet RED Compute Avr Avr < MinThres Min < Avr < Max Avr > MaxThres Calculate Packet drop probability Low probability High Drop packet Enqueue packet CS 414 - Spring 2010

  24. Packet Scheduling (in IntServ) • Isolation versus Sharing • Circuit-switched network (e.g., telephone network) – all flows are isolated, i.e., each connection has dedicated resource • Datagram-based Internet – all resources are shared on per-packet basis without any form of isolation and protection • IntServ requires scheduling algorithms to support delay bounds • Deterministic or statistical delay bounds • Deterministic and statistical bounds reflect trade-offs between isolation and sharing CS 414 - Spring 2010

  25. Packet Scheduling(in IntServ) • Simple Priority • Be careful – a large volume of higher-priority packets can easily starve lower-priority packets • Fair queuing approach • Allocate BW proportional to active flows based on their weights • Deadline-based schemes • Use EDF on packets • Rate-based scheduling framework • Has two components: regulator and scheduler • Example: token bucket with fair queuing CS 414 - Spring 2010

  26. IntServ/RSVP vs DiffServ IntServ/RSVP BB BB DiffServ CS 414 - Spring 2010

  27. Conclusion Improvements of existing transport protocols such as TCP are happening to support multimedia real-time traffic Improvements of existing IP protocols such as IP are happening to support multimedia real-time traffic CS 414 - Spring 2011

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