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Multicast Multimedia Traffic and the Design of Real-Time Protocols - - PowerPoint PPT Presentation

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Multicast Multimedia Traffic and the Design of Real-Time Protocols Bruce A. Mah bmah@tenet.Berkeley.EDU The Tenet Group University of California at Berkeley and International Computer Science Institute Y O T I F S R C A E

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Multicast Multimedia Traffic and the Design

  • f Real-Time Protocols

Bruce A. Mah bmah@tenet.Berkeley.EDU The Tenet Group University of California at Berkeley and International Computer Science Institute 16th Annual ILP Conference 10 March 1994

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Outline

Introduction and motivation Environment and methodology Measurements Analysis and other observations Conclusions and implications for protocol design

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Introduction

IP Multicast

MBONE (Multicast Backbone): Virtual network for supporting Internet-wide multicasts Multicast “sessions” and session directory

Multimedia tools

Video conferencing (nv, vic, ivs) Audio conferencing (vat, nevot) Shared whiteboard (wb) Still image distribution (imm)

Questions

What can we learn about network traffi c generated by production use multimedia applications? How can real-time network protocols best support these applications?

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Environment and Methodology

Capture packet headers for off-line processing sdsnoop: Session Directory Snoop

paradigm conviction propaganda 128.32.201 ICSI (Ethernet) 128.32.131 XCS (Ethernet) 192.107.102 Tenet (FDDI) To XUNET To campus and Sequoia 2000 MBONE routers tcpdump MBONE routers 192.128.57 XUNET

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Aggregate IP Multicast Traffi c

XUNET Video Conference 22 September 1993 11:34 AM to 1:06 PM PST

500 1000 1500 2000 1000 2000 3000 4000 5000 6000 KBits per second Time in Seconds Total IP Multicast Traffic

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Aggregate IP Multicast Traffi c

”Just an ordinary day” 20 January 1994 09:45 AM to 21 January 1994 09:47 AM PST

500 1000 1500 2000 10000 20000 30000 40000 50000 60000 70000 80000 90000 KBits per second Time in Seconds Total IP Multicast Traffic

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Audio Bitrate (vat)

XUNET Audio 22 September 1993 11:34 AM to 1:06 PM PST

20 40 60 80 100 120 140 1000 2000 3000 4000 5000 6000 KBits per second Time in Seconds

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Video Bitrate (nv 128Kbps)

law.CS.Berkeley.EDU to XUNET Video (one-second samples) 22 September 1993 11:34 AM to 1:06 PM PST

50 100 150 200 250 300 500 1000 1500 2000 2500 3000 3500 4000 KBits per second Time in Seconds law.cs.berkeley.edu

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Video (nv) Bitrate

law.CS.Berkeley.EDU to XUNET Video (fi ve second samples) 22 September 1993 11:34 AM to 1:06 PM PST

50 100 150 200 250 300 500 1000 1500 2000 2500 3000 3500 4000 KBits per second Time in Seconds law.cs.berkeley.edu

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Video (nv) Packet Sizes

law.CS.Berkeley.EDU to XUNET Video 22 September 1993 11:34 AM to 1:06 PM PST

0.2 0.4 0.6 0.8 1 200 400 600 800 1000 1200 1400 Cumulative Distribution Packet Size in Bytes

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Video (nv) Packet Interarrival Time

law.CS.Berkeley.EDU to XUNET Video 22 September 1993 11:34 AM to 1:06 PM PST

0.2 0.4 0.6 0.8 1 20 40 60 80 100 120 140 160 180 200 Cumulative Distribution Interarrival Time in Milliseconds

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Still Image Distribution (imm)

GOES-7 (Visual Satellite Images) The solution to “casual Internet usage?”

2 4 6 8 10 10000 20000 30000 40000 50000 60000 70000 80000 90000 KBits per second Time in Seconds

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Some Traffi c Analysis

20 January 1994 Trace Gross Characteristics

299 traffi c sour ces 65 destinations 1,005 conversations 722,901,051 total bytes 2,239,382 total packets

No special events this day...why so many destination addresses?

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Traffi c Br eakdown

723 MB total (all sessions)

585 MB (81.0% percent of total) from a locally-advertised “radio session” , adjusted totals exclude this session

24 advertised sessions

100 MB (72.6% of adjusted total) Still Images (imm): 46 MB Audio (vat): 42 MB Video (nv): 11 MB

7 unadvertised but known sessions

8 MB (5.5% of adjusted total)

33 unknown sessions

30 MB (21.8% of adjusted total)

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Funny User Behavior

What’s happening here?

Traffi c patterns suggest vat audio conferencing Lack of session directory advertisements suggests testing, experimentation Improper scope control (most participants in Europe, why should we see their traffi c in California?)

Suggestions

We need real multicast tree pruning! Users need education!

Hosts unreachable from NSFNET backbone

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Conclusions and Implications

Aggregate traffi c

IP Multicast traffi c still highly variable Dependent on special events and outside factors Diffi cult to constr uct a “typical” workload Flexibility is important

Audio conferencing traffi c

“Floor control” needed

Video conferencing traffi c ( nv coded)

Peak-to-average ratio of about 2:1 Large packets sent fairly frequently

User behavior

Better protection in network needed (true multicast tree pruning) User education