do twin clouds make smoothness for transoceanic video telephony ? jian li tsinghua university...
TRANSCRIPT
Do Twin Clouds Make Smoothness for Transoceanic Video
Telephony ?
Jian Li Tsinghua UniversityZhenhua Li Tsinghua UniversityYao Liu Binghamton UniversityZhi-Li Zhang University of Minnesota
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
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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.