Dr Neil DaviesCo-founder, Predictable Network
Solutions Ltd Ex: University of Bristol (23 years). Former technical head of joint university/research institute (SRF/PACT).Peter ThompsonCTO, Predictable Network Solutions Ltd Ex: GoS Networks, U4EA, SGS-Thomson, INMOS & Universities of Bristol, Warwick and Cambridge. Authority on technical and commercial issues of converged networking.Martin GeddesFounder, Martin Geddes Consulting Ltd Ex: BT, Telco 2.0, Sprint, Oracle, Oxford University. Thought leader on future of telecommunications industry. PREDICTABLE NETWORK SOLUTIONS
PREDICTABLE NETWORK SOLUTIONSDr Neil DaviesCo-founder,
Predictable Network Solutionsex-ante network performance The only Ltd Ex: University of Bristol (23 years). engineering company in the world. Former technical head of joint university/research institute (SRF/PACT). • New mathematical performance techniques. • Performance assessment methodology.Peter Thompson • World’s first network contention managementCTO, Predictable Network Solutionssolution. Ltd Ex: GoS Networks, U4EA, SGS-Thomson, INMOS & Universities of Bristol, Warwick and Cambridge. Authority on technical and commercial issues of converged networking. Consultancy on the future of telecoms andMartin Geddes the Internet.Founder, Martin Geddes ConsultingBusiness model innovation. • Ltd Ex: BT, Telco 2.0, Sprint, Oracle, Oxford University.product ideation. • Technology & • Organisation industry. Thought leader on future of telecommunicationsdevelopment. • Public & private workshops.
Every applicationhas performance needs. QoE
Aspirations time to first frame, contiguous playback audio/video quality, lack of glitches, interactivity (text, screen share) Network Expectations These always loss ? delay map onto a statistical bound on loss and delay.
A Recent Bad Skype Experience
We did a 3-way Skype call to 1.8M/448k ADSL – wholesale 20CN demonstrate the fitness-for- Loss: 0.1%. purpose issue. Delay: 40ms-50ms We measured the network loss and delay characteristics. 20M/2M Cable broadband 10M/1M ADSL Business LLU Loss: <0.5%. Loss: Wandering from a typical 0%-2% up Delay (one-way): 50ms-60ms, jumping to as high as 48% for a second or two.to 500ms for a second or two, then back Delay: 50-70ms
Averages hide essential detail Average
Delay (by Day) Average Delay (by Hour) 100 800 86.62 720.28 Reported by SamKnows Reported by SamKnows 80 668.74 600Delay (ms) Delay (ms) 60 42.63 400 40 20 21.68 200 169.71 13.79 14.51 14.49 133.06 0 0 07-May 09-May 11-May 13-May 15-May 00:00 04:00 08:00 12:00 16:00 20:00 00:00 Delay varying too Day 9th May fast for Skype to Delay (during call – afternoon of 9th) Directly measured compensate 600 Delay (ms) 400 200 0 0 10 20 30 40 50 60 70 80 Per second during call
Quality of Experience: Depends on
multiple characteristicsDetermines the chance that applications can Most stationary connection had adapt to the network the BEST Skype experience STATIONARITY HIGH Fastest connection had the WORST Skype experience LOWStationarity is the SLOW FAST SPEED Determines which inverse of applications are feasible variability
The application Hierarchy of Need
We need to evolve our metrics to capture a richer set of capabilities that contribute to fitness-for-purpose. 3. Reasonable bounds on loss and delay 2. Sufficient stationarity 1. Sufficient capacityNote: exact requirements are application-dependent
So what?• Measurement is de-facto
regulation – If your measurements are partial, your regulation is partial, and users receive a partial service!• Need a market framework for quantity and quality – Measure all network properties that impact application QoE – Encourage broadband service providers to offer a variety of trades between peak bandwidth and stationarity.
What next for regulators?• Internal
education – Dispel the bandwidth myth – Raise capability to reason on network quality management• Measure and report stationarity – Allow service providers to compete on more than just (peak) bandwidth• Engage stakeholders in a dialogue on quality – Raise external awareness and provide forum for collective industry progress