Do Twin Clouds Make Smoothness for Transoceanic Video

Telephony ?

Jian Li Tsinghua UniversityZhenhua Li Tsinghua UniversityYao Liu Binghamton UniversityZhi-Li Zhang University of Minnesota

upton@tsinghua.edu.cn

Sep. 2nd, 2015

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Outline

① Background &

Motivation② Objective & Metric

③ Dataset & Testbed

④ Results & Analysis

■ Summary of

Contribution

Video Telephony Services

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Anywhere

Any device

Anytime

Massive Popularity

Over 300M users 1PB data per day

200M users in its first two years

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Over 500M users Over 3 PB data

…

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Transoceanic Video Telephony (TVT)

Overseas study

Global trade

Online Learning

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ChallengesChallenges of transoceanic video telephony (TVT): high-rate (>500kbps) low-delay (<350ms) users sensitive to voice/video quality

degradation longer round-trip delay larger number of relay hops higher packet loss rate

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② Objective &

Metric

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Objective

Examine how today’s commercial service providers achieve smoothness for TVT?

Proprietary protocols

Encrypted data and signaling

Little info about design

choices

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A Novel MetricTo quantify the smoothness of video telephony services

L: Packet Loss Rate

R: Packet Recovery Rate

Smoothness = 1 - L*(1-R), delay<1s

Bandwidth?RTT?

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③ Dataset & Testbed

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Dataset

A real-world data trace of four popular video telephony services

App Location Timestamp Hops

Loss rate Round-trip delay and jitter

Recovery rate

Video Smoothness

File attributes recorded in our collected trace

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Testbed

Internet

Sent Packets

ReceivedPackets

Domestic video call

Transoceanic video call

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④ Results & Analysis

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Trasoceanic Video Telephony In TVT experiments, there are three data transmission paths.• The upper, blue path is used by Skype, Facetime,

and QQ• The middle path is used by WeChat• The lowermost is the detour path of WeChat

Beijing New York

IP: 114.254.** IP: 67.255.**

Beijing New York

Tianjin

Fremont

IP: 114.254.**

IP: 125.39.**

IP :184.105.**

IP: 67.255.**Beijing New York

Tianjin

Shenzhen

IP: 114.254.**

IP: 125.39.**

IP: 67.255.**

IP: 203.205.**

Beijing New York

Tianjin

Shenzhen

Fremont

IP: 114.254.**

IP: 125.39.**

IP :184.105.**

IP: 67.255.**

IP: 203.205.**

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Twin Clouds

WeChat's Video/Voice Data Delivery Infrastructure.

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Transoceanic Video Telephony

Relay hops • WeChat decreases the number of hops from 21 to

11.

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Transoceanic Video Telephony Round-trip delay and jitter• RTT of WeChat is decreasing from 1200msec to

360msec. • Jitter of WeChat is decreasing from 252msec to

90msec.

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Transoceanic Video Telephony

ISP awareness• WeChat develops the ISP-aware cloud server

selection mechanism

WeChat

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Transoceanic Video Telephony

Packet loss rate• WeChat decreases the packet loss rate from 11%,

13%, 11.6% to 7%.

Packet recovery rate• WeChat adopts aggressive retransmission strategy. (16%, 43%, 24% 56%)• Retrans traffic increase rate(2.7%, 5.9%, 3.5%

8.5%).

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Tranoceanic Video Telephony

Video telephony smoothness• TVT smoothness of WeChat is 97% on average (94.9%-98.6%)• TVT smoothness of Skype, Facetime, and QQ is

90.8%, 92.6%, and 91.2%.

WeChat outperforms the others in both the absolute value and the stability.

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Are there any drawbacks of twin clouds?

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Beijing New York

Tianjin

Shenzhen

IP: 114.254.**

IP: 125.39.**

IP: 67.255.**

IP: 203.205.**

Tranoceanic Video Telephony

Shortage of Twin Clouds’ Capacity• WeChat uses an alternative cloud located

at Shenzhen (China) to take over the data delivery.

Performance degradation!

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Tranoceanic Video Telephony

Startup time• TVT video startup delay of WeChat is ~

10s.

VS

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■ Summary of

ContributionObjective: Examine how today’s commercial service providers achieve smoothness for transoceanic video telephony (TVT) ?

Metric: Video Telephony

Smoothness

WeChat has the smoothest video which results from fewer network hops, lower loss rate and RTT, and more aggressive retransmissions.Twin clouds’ shortcomings: shortage of resource capacity, longer video startup time.

The End

Thank you!

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Domestic Video Telephony

In DVT experiments, there are two different data transmission paths.• The upper, yellow path is used by skype, facetime,

and QQ• The lower, circuitous path is used by WeChat

Beijing

Tianjin

Shanghai

IP: 114.254.**

IP: 125.39.**

IP :222.65.**

IP: 101.227.** Shanghai

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Domestic Video Telephony Relay hops • WeChat decreases the number of relay hops from

12 to 9.

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Domestic Video Telephony Round-trip delay and jitter• RTT of WeChat is decreasing from 252msec to

135msec. • Jitter of WeChat is decreasing from 110msec to

50msec

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Domestic Video Telephony

Packet loss rate• WeChat decreases the packet loss rate from 7.3%,

7.6%, 6.8% to 4.3%.

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Domestic Video Telephony Packet recovery rate• WeChat adopts aggressive retransmission strategy.

(22%, 45%, 29% 62%)• Retrans traffic increase rate. (1.9%, 3.8%, 2.3%

7.4%)

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Domestic Video Telephony Video telephony smoothness• DVT smoothness of WeChat is excellent: 98.4%• DVT smoothness of Skype, Facetime, and QQ is

94.3%, 95.8%, and 95.2%.

WeChat outperforms the others in both the absolute value and the stability.