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

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

3. Internet Multimedia Protocol Stack CS 414 - Spring 2011 AAL3/4 IP Version 4, IP Version 6 UDP Media encaps (H.264, MPEG-4) RTP ATM/Fiber Optics Ethernet/WiFi TCP SIP RTSPRSVPRTCP AAL5 KERNEL APPLICATION Layer 4 (Transport) Layer 3 (Network) Layer 2 (Link/MAC) Layer 5 (Session) MPLS DCCP

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 CS 414 - Spring 2011 VersionHeader LengthTOSTotal length identificationFlagFragment offset Time to Live (TTL)ProtocolHeader Checksum 32 bit Destination IP Address 32-bit Source IP Address VersionTraffic ClassFlow Label Payload LengthNext HeaderHop limit 128-bit Source IP Address 128-bit Destination IP Address IPv4 IPv6

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 CS 414 - Spring 2011 Appl. RSVP daemon Policy control Admission control Packet scheduler Packet classification Routing. RSVP daemon Policy control Admission control Packet scheduler Error Handling Reservation Protocol (RSVP) End-systemRouter Control Plane Data Plane

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 1. Send PATH message with TSpec from Sender to Receiver(s) 2. Send RESV message with Rspec from Receiver(s) to Sender 3. 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 CS 414 - Spring 2009 RESV messages PATH messages DATA S1 D3 D1 D2 R1R2 R3 R4 (1) TSpec (2) TSpec,RSpec (1) TSpec (2) Tspec,RSpec (1) (2) (3)

14. Mixing Reservations CS 414 - Spring 2009 RESV messages PATH messages DATA S1 D3 D1 D2 R1R2 R3 R4 15MB 10MB 15MB 3MB 12MB Mixing 3MB 10MB 15MB 12MB Mixing 12MB

15. Reservation Structures Resource Reservation Table  Stores admitted/reserved resources RSVP Messages CS 414 - Spring 2009 VersionFlags Send TTL Message Type Reserved RSVP Checksum RSVP Length

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) CS 414 - Spring 2010 Packet Scheduler Input Queue IP packet MinThres – Min. Queue Length Threshold MaxThres – Max Queue Length Threshold Avr – Average Queue Length

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 Compute Avr Calculate Packet drop probability Drop packet Enqueue packet Avr < MinThresMin < Avr < MaxAvr > MaxThres Low probabilityHigh RED

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 IntServ/RSVP vs DiffServ BB DiffServ

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