Raj Jain Professor of Computer and Information Sciences ...jain/talks/ftp/netsem5.pdf ·...

Raj JainThe Ohio State University

1

Raj JainProfessor of Computer and Information Sciences

The Ohio State UniversityColumbus, OH 43210

[email protected] http://www.cis.ohio-state.edu/~jain/

Network

Raj Jain

jain@cse horizontal


2

Media SynchronizationMultimedia over ATMMultimedia over IP: MBONE, RSVP,...Interesting applications on Internet

Overview


3

Local Multimedia

No bandwidth sharing ⇒ Constant bit rateCircuit switching ⇒ No buffering

No delay variationNo (negligible) loss

MultimediaSource


4

Multimedia Synchronization

Playout Synchronization: Play signal generated at t at t+∆inspite of variable network delayInter-Media Synchronization: Between audio and video(Lip sync)Intra-Media Synchronization : All receivers play at thesame time (simulations and wargaming)Playout is required for all continuous media. Intra- andInter- may or may not be required.

MultimediaSource

Network


5

Timestamps

Unit: frame (not good for variable frame rate), ms, µs, sBits: 10, 32, 33, 64Wrap around may cause confusionMPEG uses 33-bit clock with a resolution of 90 kHzDivisible by 24 Hz, 25 Hz, 29.97 HZ, and 30 HzHowever, 33-bits are one too manyNetwork video protocol (NVP) uses 10-bit timestamps.For 20-ms audio packets, it wraps around in 20.5 s.

Open at10:30:3.123

Open at10:30:3.223


6

Error ControlOptions:

NoneError detection with no indication to applicationError detection with indication to applicationError detection with retransmissionError Correction: Forward error correctionError Concealment: Freeze frame

Header errors: May cause mis-synchronization, wrongcoding identificationData errors: Easier to toleratePacket loss: Good to have sequence numbersPacket reordering: Need sequence numbers


7

Multimedia over ATMService Aspects and Applications (SAA) Group

MPEG2 over ATMKey Issues:

What Applications?Transport stream or program stream?Which ATM Adaptation Layer (AAL)?What signalling parameters and values?


8

What Applications?MPEG1 for VHS-quality video/audioMPEG2 for theater-quality video/audioVideo on Demand ⇒ High-quality ⇒ MPEG2CBR encoded MPEG2 transport streams are most common⇒ Do we need CBR transmission?


9

CBR vs VBR

CBR

WastedBandwidth

Buffering Buffering

No Buffering

Compression

VBR

CBR

VBRTransmission

Compression

Transmission


10

Which AAL?

AAL1: Designed for CBR,Provides forward error correction optionContains time-stampLess overhead than AAL5Ideal fit: 188 byte MPEG2 transport packet = 4 cells

AAL5: Implemented universally ⇒ Low costUsed for signaling and LAN emulation

ATM ApplicationATM Adaptation Layer

ATM


11

Cell Delay VariationInstantaneous Cell-Delay Variation (I-CDV)Actual-Expected arrival timeExpected = Emission + Nominal delayCell Delay Variation Window (CDV-W)CDV-W = |I-CDV(Max)| + |I-CDV(Min)|Cells arriving outside window are considered lostLarge CDV ⇒ Large buffers ⇒ Higher cost

Expected Actual


12

Status and PlansSend to Forum membership for approval in September 1995Future:

Select QoS parametersVBR MPEG2Other compression standardsOther applications


13

Multimedia over IPMulticast Backbone: MBoneProtocols:

RSVPRTPST2

Applications:CU-SeeMeInternet Talk RadioINETphone servers

Other Audio-Visual Tools: vat, nv, ivs, ...


14

MBoneInternet Multicast backboneA set of routers that implement IP multicastingIP multicast address: start with 1110... (binary),224.0.0.0 to 239.255.255.255 (decimal)

NWnet MIDnet PSC

Cornell

NEARnet

ARPA

JvNC

MeritNCAR

NSI UIUCHawaii

SDSC SESQUIGATech ANS

PSI

SURA

Alternet

MCNC

BARRNet


15

MBone (Cont)Uses radio/tv station paradigm: Sender is allocated amulticast address and it starts transmitting on that addressAnyone can listen by tuning into the multicast addressby sending an Internet Group Management Protocol (IGMP)request to router to join the multicastThe router provides a connection to the nearest pointSender has no idea of who is listeningSender controlled multicasts does not scale well.First audiocast in March 1992: IETF meeting to 20 sitesNow over 600 hosts in over 15 countriesPrograms include space shuttle, conferences, IETF,...President Clinton and VP Gore have appearedIs a source of heavy traffic, congestion, and complaints


16

MroutedThe routing protocol that allows IP multicastSoftware available on the Internet.Join the MBone mailing list.Many vendors implement it already in their routersTo connect find the nearest Mrouted.Maps available on the net.Mrouteds setup tunnels between them.Tunnel = direct connectionRouters on the path of the tunnel donot need to knowmulticasting.


17

Tunnels

Implemented by encaptulating the entire packet in anotherIP header.Each tunnel has a cost. Least cost path is found byexchanging distance-vectors with neighbors.

IP Header DataIP Header Data IP Header

S A B C D

S-to-D A-to-C


18

Tunnels Are ExpensiveEach tunnel requires 100 to 300 kbps.Use 500 kbps for design.A few tunnels can saturate the host.Four on SPARC 1, six on SPARC 10.Fifteen tunnels can saturate an Ethernet.Maximum two tunnels over T1.Each packet has a time to live (TTL).TTL is decremented at each router.The packet is forwarded iff its TTL is over a threshold.Periodically, leaf mrouteds poll to see if there are any listers.Pruning: If a mrouted gets a packet for which it has no listeners,it sends a message to the upstream mrouted to stop sending.


19

MBONE: ReferencesH. Eriksson, "MBone: The Multicast Backbone," CACM, August 1994, pp. 54-60.RFC 1112, "Host extensions for IP Multicasting"S. Casner, et al, "Frequently Asked Questions (FAQ) on the Multicast Backbone(MBone)," http://www.research.att.com/mbone-faq.htmlSee also http:://www.cs.ucl.ac.uk/mice/faq.htmlM. Macedonia and D. Brutzman, "Mbone Provides Audio and Video Across theInternet," Computer, April 1994, pp. 30-36.MBONE: List of available s/w and FTP sites http:://www.cs.ucl.ac.uk/mice/mbone-soft.htmlMBONE Routers and Linkshttp:://info.arl.army.mil/ACIS/ACD/MBONE/mbone-routers.htmlMBone interest group mailing list: [email protected] announcements mailing list:[email protected]


20

IP Multimedia Toolsvat - Visual audio tool (conferencing)by Steve McCane and Van Jacobsen of LBLnevot - Network voice terminal (conferencing)by Henning Schulzrine of AT&Tivs - INRIA video conferencing system by Thierry Thurlenv or NetVideo - network video by Ron Frederick of Xeroxvic - Video conferecing toolwb - White board (shared drawing space)by McCane and Jacobsenimm - Image (JPEG) multicast clientby Winston Dang of U. Hawaiisd - Session directory tool for MBone programs


21

IP Multimedia Tools (Cont)mmcc - Multimedia conference control by Eve Schooler ofUSC/ISImmphonemedia on demand server by Anders Kelmets of RITStockholm (Allows unicast replays of past Mbone sessions)CuSeeMe - Desktop video conferencingMulticast reflectorsmaven - Audioconferencing tool

Ref: http://www.lbl.gov/ctl/vconf-faq.html


22

RSVP

ReSource Reservation ProtocolSimplex streams between sources and receiversReceiver initiated ⇒ ScalableReceiver requests are propagated upstream towards thesendersRouters may merge requests from many receivers

S1

S2

R1

R2 R3

R4 H5

H4

H3

S1

S2

R1

R2 R3

R4 H5

H4

H3


23

RSVP (Cont)Routers maintain a soft state. The receivers have to refreshperiodically.Routers have a packet classifier and a schedulerProvides many different reservation styles

Any source but a given multicast destinationList of sources (fixed or dynamic)Allows receivers to switch channels

Routing trees from sourcesSink trees from receivers


24

RSVP: ReferencesL. Zhang, et al, "RSVP: A New Resource ReServationProtocol," IEEE Network 1993.R. Braden, et al, "Resource ReServation Protocol (RSVP) --Version 1 Functional Specification," Internet draft, March24, 1995, ftp://ietf.cnri.reston.va.us/internet-drafts/draft-ietf-rsvp-spec-05.txtD. Mitzel, et al, "An Architectural Comparison of ST-II andRSVP," Infocomm'94.ftp://catarina.usc.edu/pub/mitzel/Infocom94/infocom94.psRSVP, http://www.isi.edu/div7/rsvp/Mailing list: [email protected]


25

CuSeeMeVideo conferencing softwareWorks on any system connected to Internet: PC, MACs,workstationsDeveloped at Cornell University. Sponsored by NSF.Software available free on the netProvides one-to-one connectionOne-to-many connection feasible using a reflectorReflector software for Sun workstations is availableMany public reflector sites


26

CuSeeMe (Cont)Receivers need only normal video cardsSenders need a video capture card and a video cameraCaptures 8-bit 160X120 video images. Displays 4-bitgrayscale video at a low frame rate.Audio sounds are occasionally broken.

Ref: http://magneto.csc.ncsu.edu/Multimedia/Classes/Spring94/projects/proj6/cu-seeme.html


27

Internet Talk RadioLike National Public Radio on the InternetSupported by Sun Microsystems and O'Reilly & AssociatesRun by Carl MalamudCovers networking topicsDoes not use MBone. Audio files are distributed.Geek of the Week program features key InternetpersonalitiesThe Incidental Tourist features restaurant reviewsKey sessions of the many conferences are rebroadcastFor further info [email protected]

Ref: http://www.cmf.nrl.navy.mil/radio/ITRintro.readme.html


28

INETPhone:Internet Phone Servers

Being designed by Multiparty MUltimedia SessIon Control(MMUSIC) working group of IETFOpen ownership of phone service (similar to internet)Telephone servers (similar to routers)Incoming and outgoing local phone lines on one sideInternet connections on the other side

InternetServer

Server

Server


29

INETPhone (Cont)Receive local calls, determine the internet route and forwardAccept remote calling requestsLocal call, Internet, local callDirectory servers map INETPhone servers IP addresses tophone numbers

Ref: RFC 1789, "INETPhone: Telephone Services and Serverson Internet," April 1995.


30

Summary

Constant bit rate MPEG2 video on demandUses VBR AAL5 for CBR videoTCP/IP protocols suite is being extended to allow multimediaon Internet.Multicast backbone (Mbone), Resource reservation (RSVP)Internet talk radio and Internet phone


31

AcronymsAAL: ATM Adaptation LayerADSL: Asymmetric Digital Subscriber LineAMS: Audiovisual Multimedia ServicesATM: Asynchronous Transfer ModeAVIS: Audiovisual Interactive ServicesBRI: Basic Rate InterfaceCATV: Cable TelevisionCBR: Constant Bit RateCBT: Core-Based TreesCDV-W: Cell Delay Variation WindowCDV: Cell Delay VariationCELP: Code-excited liner predictionCMMC: Conference Management and Multiplexing CenterCRC: Cyclic Redundancy Check


32

CSMA/CD: Carrier Sense Multiple Access with Collision DetectionFEC: Forward Error CorrectionFTTC: Fiber to the CurbGSM: Groupe Special Mobile (cellular phone standard)HDSL: High-Speed Digital Subscriber LineI-CDV: Instantaneous Cell Delay VariationIDMR: Inter-Domain Multicast RoutingIGMP: Internet Group Management ProtocolJPEG: Joint Picture Experts GroupLEC: Local Exchange CarrierMBone: Multicast BackboneMIME: Multipurpose Internet Mail ExtensionsMMUSIC: Multiparty MUltimedia SessIon ControlMOSPF: Multicast Extensions to OSPFMOSPF: Multicast Open Shortest Path FirstMPEG: Motion Picture Expert GroupNVoD: Near Video on DemandPCR: Program Clock Reference


33

PCR: Program Clock ReferencePDU: Protocol Data UnitPIM: Protocol Independent MulticastPIM: Protocol Independent MulticastPRI: Primary Rate InterfacePS: Program StreamPTS: Presentation Time StampQoS: Quality of ServiceRBB: Residential BroadbandRSVP: Resource ReServation ProtocolRTP: Real-time Transport ProtocolSAA: Service Aspects and Applications GroupSCMP: Stream Control Message ProtocolSDP: Session Description ProtocolSRTS: Synchronous Residual Time StampST2: Internet Stream Protocol Version 2STC: System Time Clock


34

TS: Transport StreamTTL: Time to liveVBR: Variable bit rateVCO: Voltage Controlled OscillatorVoD: Video on Demand

Raj Jain Professor of Computer and Information Sciences ...jain/talks/ftp/netsem5.pdf ·...

Documents

Transcript of Raj Jain Professor of Computer and Information Sciences ...jain/talks/ftp/netsem5.pdf ·...