SIMULATION RESULTS FOR MULTI-STREAM

draft-ietf-avtcore-rtp-multi-stream-01draft-ietf-avtcore-rtp-multi-stream-optimisation-00

SIMULATION RESULTS FOR MULTI-STREAM

https://datatracker.ietf.org/doc/draft-ietf-avtcore-rtp-multi-stream/

https://datatracker.ietf.org/doc/draft-ietf-avtcore-rtp-multi-stream-optimisation/


Simulation Results for Multi-Stream | IETF 88 AVTCORE WG | Magnus Westerlund | Page 2

› Current Status› Simulation Purposes› SSRC Report Aggregation Issue› Report Group Extension performance gains

– RTCWEB use case– Selective Forwarding Middlebox use case

› Next Steps

Overview


› Neither drafts was updated before this meeting› draft-ietf-avtcore-rtp-multi-stream-01 Issues:

– How does the RTCP Scheduler work when aggregating– How does one calculate avg_rtcp_size when aggregating– Need for unicast session joiners use of no initial delay

› draft-ietf-avtcore-rtp-multi-stream-optimisation-00– Missing Signaling Specification– Security Considerations needs extended

› Both Drafts will benefit from further editing› However, focus on first resolving open issues

Current Status




› Determine size of issue with SSRC aggregation› Enable trying out proposals to fix issues› Verifying that what we write works as intended

Simulation Purpose


› Simulating what happens when an end-point performs SSRC RTCP Report aggregation

› Implementation does the following:– Schedule all SSRCs– When a SSRC is scheduled for transmission– Fill compound packet with the triggered SSRC’s:

- RTCP SR/RR- SDES CNAME

› Plus as many of the nearest scheduled SSRCs reports that fit in MTU

– Send Packet– Reschedule all of the sent SSRCs

SSRC Aggregation


› Simulation case RTC:– Two endpoints– Each endpoint has 4 SSRC, all four active senders

› Members = 8› Senders = 8

– RTCP bandwidth› RS: 10 kbps› RR: 15 kbps

– Regular AVPF› T_RR_INT = 0› Include Full Cross Reporting

- Each SSRC reports on the other 7

SSRC Aggregation


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 30

5000

10000

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20000

25000

30000

35000

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BaselineAggregatedAdjusted

Freqency (RTCP Packets / bin)

Transmissioninterval (s)

SSRC AGGREGATIONRTCP Transmission Interval Distribution

Bitrates AVG_RTCP_SIZE

Aggregated: 7807,92 916

Baseline: 24987,46 250

Adjusted: 31251,69 228


› The documented issue for SSRC aggregation in draft-ietf-avtcore-rtp-multi-stream-01:

› The issue really exists:– RTCP transmission interval significantly increased– Implementation of scheduling changes the interval distribution

› Using the basic idea and scaling AVG_RTCP_SIZE with number of reporting SSRCs per packet

– Overshoots the RTCP bandwidth significantly (25%)– Appears to be due to scheduling implementation

› Picks the best out of the SSRCs (4) being aggregated› Need to figure out better compensation / scheduling

Conclusions



› Implements the report group extensions from– draft-ietf-avtcore-rtp-multi-stream-optimisation-00

› Active Reporter:– Reports on remote SSRCs, not any within the same report group– Includes an extra Source Description item with report group– Will be multiple ones if SSRC to report are more than 31

› Non Reporter– Only sends regular SR or RR without any report blocks– Extra Reporter Sources RTCP Packet (4+4*Reporters bytes)– These simulations are done without SSRC aggregation

› Simulated Two different Use Cases

Report Grouping



› Simulation case RTC:– Two endpoints– Each endpoint has 4 SSRC, all four active senders

› Members = 8› Senders = 8


– Regular Reporting in AVPF› T_RR_INT = 0

– Baseline:› Include Full Cross Reporting

Report Grouping: RTC CASE


RTC Use case ResultsRTCP Transmission Interval

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

10000

20000

30000

40000

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60000

70000

BaselineReport Groups

Transmission Interval (s)

Frequency (RTCP Packets / bin)


RTC Use case ResultsPacket Size Distribution

0 25 50 75 100 125 150 175 200 225 2500

20000

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60000

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120000

BaselineReport Group


Packet Size (Bytes)

AVG_RTCP_SIZE

Baseline 250

Report Groups 119



– Regular Reporting in AVPF› T_RR_INT = 0

– Baseline:› Include Full Cross

Reporting

› Simulation case SFM:– Two endpoints– Endpoint 1:

› Total SSRCs: 80› Sending SSRCs: 20

– Endpoint 2:› Total SSRCs: 120› Sending SSRCs: 42

– Members = 200– Senders = 62

Selective Forwarding MiddleBOX Use CASE

STM STMCC

C

C

C

C

C

C


SFM Use case ResultsRTCP Transmission Interval

0.00 1.20 2.40 3.60 4.80 6.00 7.20 8.40 9.60 10.80 12.00 13.20 14.40 15.60 16.80 18.00 19.20 20.40 21.60 22.800

2000

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16000

Report GroupsBaseline


Transmission Inter-vall (s)


0 50100

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250300

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650700

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850900

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Report GroupBaseline


Packet Size (Bytes)

SFM Use case ResultsPacket Size Distribution

AVG_RTCP_SIZE

Baseline 818

Report Groups 101


› Report Groups are as effective as we expected– Allows either

› More frequent reporting› Reduced consumption for regular reporting

› Significant improvements– Even in quite small sessions of the RTC use case

› Gain should be even more with SSRC Aggregation

Conclusions


› draft-ietf-avtcore-rtp-multi-stream-01– SSRC Aggregation Issue

› Needs proposals for solutions- Simple to implement- Maintain RTCP Bandwidth Target

– Need to look at effects of RTCP packet burst of joining multi-SSRC endpoint

› draft-ietf-avtcore-rtp-multi-stream-optimisation-00– Resolve editorial and missing sections

Next Steps



Documents

SIMULATION RESULTS FOR MULTI-STREAM