CS 414 Multimedia Systems Design Lecture 22 Multimedia

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

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

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

Layer 3 Internet Services n Internet Protocol (IP) – IP Version 4 ¨ Provides unreliable deliver of datagrams in a point-topoint fashion ¨ Runs on top of any Layer 2 technologies ¨ Supports n IP address of 32 bits n Different types of services (TOS) ¨ Precedence relation ¨ Services such as minimization of delay, maximization of throughput n Multicast ¨ Internet Group Management Protocol for managing groups CS 414 - Spring 2011

New Internet Protocol - IPng n Next Generation IP – IP Version 6 ¨ Supports n n 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

IP Packet Headers Version Header Length TOS Total length identification Flag Time to Live (TTL) Fragment offset Protocol Header Checksum 32 -bit Source IP Address IPv 4 32 bit Destination IP Address Version Traffic Class Payload Length Flow Label Next Header 128 -bit Source IP Address 128 -bit Destination IP Address CS 414 - Spring 2011 Hop limit IPv 6

Qo. S in Layer 3 Internet Integrated Services n To provide network Qo. S in the Internet, IETF reacted by Creating Working Group (Int. Serv) ¨ Deploying Internet Integrated Services ¨ n Development of Control (Establishment) Protocol to reserve resources per flow ¨ n Resource Reservation Protocol (RSVP) Development of Qo. S-aware network services within IP ¨ Guaranteed class-of-service n ¨ Deterministic Qo. S guarantees Controlled-load class-of-service n Statistical Qo. S guarantees CS 414 - Spring 2011

Integrated Services (Int. Serv) Architecture Reservation Protocol (RSVP) End-system Router Control Plane Appl. RSVP daemon Policy control Routing. Admission control Packet classification RSVP daemon Policy control Admission control Packet scheduler Error Handling Data Plane CS 414 - Spring 2011 Packet scheduler

RSVP n Provides reservation for data flows ¨ Flow specification is represented via n Traffic specification, TSpec ¨ n Request specification, Rspec ¨ n n Description of required Qo. S (desired flow behavior) Is receiver-oriented and unidirectional Uses two types of messages: ¨ n Characteristics of the data flow PATH messages and RSVP messages Protocol 1. 2. 3. 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 Qo. S CS 414 - Spring 2009

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

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

Service Requirements (Application-specific) n n 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

RSVP Control and Data Flow S 1 (3) (1) TSpec (1) R 1 (3) D 1 R 2 (2) TSpec, RSpec (2) Tspec, RSpec (2) (1) (3) (2) Tspec, RSpec R 3 R 4 D 3 RESV messages PATH messages (3) (1) TSpec DATA CS 414 - Spring 2009 D 2

Mixing Reservations 15 MB S 1 Mixing R 1 12 MB 15 MB Mixing R 2 10 MB 3 MB 12 MB 15 MB D 3 RESV messages PATH messages D 1 R 3 3 MB R 4 12 MB 15 MB DATA CS 414 - Spring 2009 D 2

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

RSVP Features n n n 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

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

Guaranteed Service (in Int. Serv) n n n Provides guaranteed BW and strict bounds on end-toend 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

Guaranteed Service (2) n 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. n n n This service does policing and shaping Resources are reserved at worst case For bursty traffic sources – low network utilization CS 414 - Spring 2010

Controlled Load Service (in Int. Serv) n No quantitative guarantees on delay bound or BW n 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 ¨ n Invocation and Policing ¨ Specify TSpec (average values) and do admission, reservation, policing based on average TSpec CS 414 - Spring 2010

Int. Serv (Error Handling Early Congestion Avoidance) Avr – Average Queue Length Max. Thres – Max Queue Length Threshold Min. Thres – Min. Queue Length Threshold IP packet IP packet Input Queue CS 414 - Spring 2010 Packet Scheduler

Int. Serv (Error Handling) Discard Algorithms n 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 (Min. Thresh). If max. threshold (Max. Thres) is exceeded, all packets are dropped n WRED – Weighted RED ¨ Drops packets selectively based on IP precedence CS 414 - Spring 2010

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

Packet Scheduling (in Int. Serv) n Isolation versus Sharing ¨ Circuit-switched n 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 Int. Serv 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

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

Int. Serv/RSVP vs Diff. Serv Int. Serv/RSVP BB BB Diff. Serv CS 414 - Spring 2010

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