Energy Efficient BitTorrent for Green P2PFile Sharing
Giuseppe Anastasi
Pervasive Computing & Networking Lab (Perlab)
Dept. of Information Engineering, University of Pisa
E-mail: giuseppe.anastasi@iet.unipi.it
Website: www.iet.unipi.it/~anastasi/
Acknowledgements
Ken Christensen, University of South Florida, USA
Ilaria Giannetti, University of Pisa, Italy
Marco Conti, Andrea Passarella, IIT-CNR, Italy
Helmut Hlavacs, University of Vienna, Austria

PerLab

Koc University, Istanbul, July 5, 20121

Acknowledgments
PerLabICT Action IC0804
Energy Efficiency in Large-Scale Distributed Systems
Starting date : 23/01/2009
End of action : 04/05/2013
Additional info at

http://www.irit.fr/cost804/
Energy Efficient BitTorrent for Green P2P File Sharing

22Overview
PerLabIntroduction
Motivations forEnergy Efficient Internet
Energy Efficient P2P File Sharing

Energy Efficient BitTorrent
Green BitTorrent
Proxy-based BitTorrent
Download Sharing

Conclusions

Energy Efficient BitTorrent for Green P2P File Sharing

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The Energy Problem
PerLabDramatic increase in the global energy consumption
Energy is a not renewable and limited resource
Environmental pollution and planetary overheating

Energy consumption of Internet
74TWh/year in US (equivalent to $ 6 billions)
2-3% of the total energy consumption in US
About 1/3 of this energy could be saved by simple power
management techniques(Source: Lawrence Berkeley National Laboratory, USA, 2006)

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Where Energy is consumed
PerLabInternet Core
Routers , Switches, Access Points, Links

Data Centers
Servers

User Devices
PCs, Printers, Displays, …

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5

Edge Devices
PerLab

Most of the energy wastes occurs at edges
Data centers
User devices

Energy Consumption
Data Centers: 2 TWh per year
User Devices: 16 TWh per year
User devices are widespread and very numerous
User devices are often left powered on even if idle
People typically do not pay attention to energy issues(Source: Lawrence Berkeley National Laboratory, USA, 2006)

Energy Efficient BitTorrent for Green P2P File Sharing

66

On-going Research Projects
EARTH

PerLabEnergy Aware Radio and neTwork Technologies
IP project, EU FP7, https://www.ict-earth.eu/

BCG2
Beyond Cellular Green Generation
Green Touch Consortium

ECONET
low Energy COnsumption
NETworksCONET
3-year IP project, EU FP7, https://www.econet-project.eu/

TREND
Towards Real Energy-efficient Network Design
NoE, EU FP7, http://www.fp7-trend.eu/

CoolEmAll
Energy efficient data centers
EU FP7, http://www.coolemall.eu/……

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7

Energy Efficiency in the Internet Core
PerLab

Re-Engineering
More energy-efficient network devices throughEnergy-Efficient SiliconComplexity Reduction

Dynamic Adaptation
The capacity of network elements is dynamically modulated so as tomeet actual traffic loads
Performance Scaling
Idle Logic

Sleeping/Standby
Unused network/device portions are put in low-power mode

R. Bolla, R. Bruschi, F. Davoli, F. Cucchietti, Energy Efficiency in the Future Internet: A Survey of
Existing Approaches and Trends in Energy-Aware Fixed Network Infrastructures, IEEE
Communications Surveys and Tutorials, Vol. 13, N. 2, 2011.
Energy Efficient BitTorrent for Green P2P File Sharing

88Personal Equipments
PerLabSome statistics about people behavior
43,5% of UK population uses PC at work and
18% never powers it off
16% sometimes powers it off
Energy wastage corresponding to
153 millions of €700.000 tons of CO2

Motivations for not powering off
It is no so important
It takes some time and I am always in a hurry
I simply forget to power off
I don’t want to lose my work
Nobody else turns PC off , so …
….
(Source: National Energy Foundation, UK, 2007)
Energy Efficient BitTorrent for Green P2P File Sharing

99Causes for energy wastes
PerLabPCs left on for
Laziness, Omissions, …

PCs intentionally left on for maintaining connectivity
Remote login
Automatic software upgrades

PCs intentionally left on for
P2P file sharing applications

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10Possible Solutions
PerLabCentralized Shutdown
Already used in data centers and labs
No flexibility

Laziness
OmissionsPower Manager [Chi10]
Better flexibility
Luca Chiaraviglio, Marco Mellia, PoliSave: Efficient Power Management of Campus
PCs, IEEE SoftCOM - 18th International Conference on Software,
Telecommunications and Computer Networks, Bol, Croatia, September 2010

Context-aware Power Management [Har05]
Uses low-power sensors/devices to predict the user’s
intention to use/not use the PC[Har05] C. Harris, V. Cahill, Power Management for Stationary Machines in a
Pervasive Computing Environment, Proc. 38th Hawaii International Conference on
System Sciences, 2005.
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11

Possible Solutions
PerLabNetwork Connectivity Proxy (NCP) [Jim08]
Based on proxying + Magic Packet
Somniloquy [Aga09]
Sleep Server [Aga10]

Permanent
Connectivity[Jim08] M. Jimeno, K. Christensen, B. Nordman, A Network Connection Proxy to Enable Hosts to
Sleep and Save Energy, Proc. IEEE International Performance Computing and Communications
Conference, pp. 101-110, December 2008.
[Aga09] Y. Agarwal, S. Hodges, J. Scott, R. Chandra, P. Bahl, R. Gupta, Somniloquy: Augmenting
Network Interfaces to Reduce PC Energy Usage, Proceedings USENIX Symposium on Networked
System Design and Implementation (NSDI, 2009), Boston, MA, USA, April 22-24, 2009.
[Aga10] Y. Agarwal, S. Savage, and R. Gupta, SleepServer: Energy Savings for Enterprise PCs by
Allowing them to Sleep, Proceedings of the USENIX Annual Technical Conference, June 2010.

Energy-aware Applications and Protocols

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P2P Applications
PerLab

P2P Traffic in Internet

Source: Ipoque 2008 / 2009
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13

P2P Applications
PerLab

P2P Traffic originated by BitTorrent

Source: Ipoque 2008 / 2009
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14

BitTorrent

15

BitTorrent Terminology
PerLabpeer: node of the
BitTorrent overaly❒ P2P file
distribution

leechertorrent: group ofpeers exchanging
chunks of a fileseeder

tracker: tracks peers
involved in the torrent
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16

BitTorrent Protocol
PerLabFile divided into 256KB chunks.
Peers download chunks from a multitude of other peers
Instead from a single server, as in the traditional C/S approach

While downloading, peers upload chunks to other peers
Once a peer has entire file, it may (selfishly) leave or(altruistically) remain
Peers may come and go

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17

BitTorrent Protocol
PerLabtorrent server:
contains .torrent files
tracker: tracks peers
participating in torrent

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18

Tit-for-Tat Policy
PerLab

A peer continuously measures the bit rate achievedby each of its neighbors
And uploads chunks to the 4 neighbors from which itis achieving the highest bit rate
re-evaluate top 4 every 10 secs

Every 30 secs: randomly select another peer, starts
sending chunks
newly chosen peer may join top 4“optimistically unchoke”

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19

Rarest First Policy
PerLabAt any given time, different peers have different
file chunks
Periodically, a peer asks each neighbors for thelist of chunks they have.
And sends requests for missing chunks, giving
priority to chunks that are less spreadrarest first

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20

BitTorrent andEnergy Efficiency

21

P2P and Energy Efficiency
PerLabEnergy Efficiency in BitTorrent (and P2P) has notreceived significant attention so far
Most of the proposed optimizations aimed at
improving performance
Only indirectly address energy efficiency

Motivations
Energy consumption is distributed among a large
number of peers
No central entity pays for the energy consumed by
P2P applications (e.g., BitTorrent)
22
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22

Key Question
PerLabIs it more energy efficient todownload a song from BitTorrent
rather than iTunes?

S. Nedevschi, S. Ratnasamy, J. Padhye
Hot Data Centers vs. Cool Peers,
Proc. Workshop on Power Aware Computing and Systems (HotPower 2008),
San Diego, CA, USA, Dec 7, 2008.
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23

P2P vs. Client-Server
PerLabEnergy consumption model of P2P and CS is nota trivial task
CS is typically more energy efficient than P2P in
the network side
Multiple hops needed to distribute the file between peers
Membership maintenanceP2P is likely to be more energy efficient than CS
at end systems
Most of the energy consumed at data centers is due to cooling
They do not consider the baseline energy consumption of PCs
S. Nedevschi, S. Ratnasamy, J. Padhye, Hot Data Centers vs. Cool Peers, Proc. Workshop on Power Aware Computing and
Systems (HotPower 2008), San Diego, CA, USA, Dec 7, 2008.
Reliable & Energy-Efficient Data Delivery in WSNs with Multiple Mobile Sinks

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P2P vs. Client-Server
PerLab

P2P is a mean of reducing energy
consumption at data centers
Users are both content consumers and content
distributors

P2P pushes energy consumption out of data
centers
into the homes of users

J. Blackburn, K. Christensen, A Simulation Study of a New Green BitTorrent, Proc. International Workshop on Green
Communications (GreenComm 2009), Dresden, Germany, June 2009.
Energy Efficient BitTorrent for Green P2P File Sharing

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25

BitTorrent and Energy Efficiency
PerLab

BitTorrent is not “energy friendly” for users
Peers must remain connected during the entire
download process
Powering off a peer stops the download process

Coordinated strategies for energy efficiency are
unfeasible
They would be in contrast with the BitTorrent design paradigm

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26

Average Download Time
PerLabPopular Files

D. Qiu, R. Srikant, Modeling and Performance Analysis of BitTorrent-like Peer-to-Peer Networks, Proceedings of ACM
Sigcomm 2004, Portland, Oregon, USA, pp 367–378.
Reliable & Energy-Efficient Data Delivery in WSNs with Multiple Mobile Sinks

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27

Average Power Consumption
PerLabPopular Files – Each peer consumes one unit of power

Optimal
Average
Seeding Time

H. Hlavacs, R. Weidlich, T. Treutner, Energy Efficient Peer-to-Peer File Sharing, Journal of Supercomputing, to appear.
Available online at http://www.springerlink.com/content/k56811t52n134811/
Reliable & Energy-Efficient Data Delivery in WSNs with Multiple Mobile Sinks

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28

Limits of the previous approach
PerLabThe optimal avg. seeding time depends on anumber of parameterswhich are not under the user control
and vary over time

The optimal seeding time is unknown to the user
The user is typically selfish and lazy
He is mainly interested in getting a copy of the file
Not in optimizing the energy consumption of the system atthe cost of an increase in his/her personal consumption

He typically leaves the swarm after some time the filehas been downloaded
Energy Efficient BitTorrent for Green P2P File Sharing

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29

Proposed Approaches
PerLab

Green Bit Torrent
J. Blackburn, K. Christensen, A Simulation Study of a New Green BitTorrent, Proc. International Workshop
on Green Communications (GreenComm 2009), Dresden, Germany, June 2009.

Proxy-based BitTorrent
G. Anastasi, I. Giannetti, A. Passarella, A BitTorrent Proxy for Green Internet File Sharing: Design andExperimental Evaluation, Computer Communications, Vol. 33, N. 7, pp. 794-802, May 2010. Elsevier.
I. Giannetti, G. Anastasi, M. Conti, Energy-Efficient P2P File Sharing for Residential BitTorrent Users,
Proc. IEEE International Symposium on Computers and Communications (ISCC 2012), Cappadocia, Turkey,
July 1-4, 2012.

Download Sharing
H. Hlavacs, R. Weidlich, T. Treutner, Energy Efficient Peer-to-Peer File Sharing, Journal of Supercomputing,available online at http://www.springerlink.com/content/k56811t52n134811/.

Energy-Efficient Mobile BitTorrent
I. Kelenyi, A. Ludanyi, J. Nurminen, I. Pusstinen, Energy-efficient Mobile BitTorrent with Broadband Router
Hosted Proxies, Proc. IFIP Wireless and Mobile Networking Conference (WMNC 2010), Budapest, Hungary,
October 13-15, 2010.
I. Kelenyi, A. Ludanyi, J. Nurminen, BitTorrent on Mobile Phones – Energy Efficiency of a Distributed
Proxy Solution, Proc. International Green Computing Conference (IGCC 2010), Chicago, USA, August 15-18,
2010.
Energy Efficient BitTorrent for Green P2P File Sharing

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30

Green BitTorrent

31Motivations
PerLabUsing the optimal seeding time is unfeasible
It cannot be calculated
The user is selfish and lazy

Green BitTorrent tries to implement the idea
behind the above ideal approach
Peers should remain available after they havecompleted their download
At the same time, they should not consume energy forothersThe user should not be directly involved

Energy Efficient BitTorrent for Green P2P File Sharing

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32

Basic Idea
PerLab

Extended version of BitTorrent to allow power
management at the user’ s PC
Allows BitTorrent peers to sleep …
when they are not downloading/uploading… while remaining active members of the swarm
Ensures backwards compatibility
Green BitTorrent peers can operate with legacy
BitTorrent peers
Some performance degradation

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33

Challenge
PerLab

BitTorrent relies on TCP connections
A peer establish at TCP connections with its
neighborsat most max_connect

A client stopping a TCP connection isconsidered disconnected
Challenge:
Is there a way to maintain TCP connectivity
while sleeping?

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34

States of another peer
PerLabConnected
A peer that this peer has an active TCP connection with.
File pieces can be uploaded and downloaded on the connection

Sleeping
A peer that has disconnected its TCP connection with thispeer.
The TCP connection must be re-established before file pieces
can be uploaded or downloaded.

Unknown
A peer that has been given to this peer by the tracker, and
it is unknown if the peer is sleeping or awake.
Energy Efficient BitTorrent for Green P2P File Sharing

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35

Additional mechanisms
PerLabInactivity timer
Restarted whenever a download/upload activity
occurs

Magic packet
Used to wakeup a remote sleeping peer
The receiving network interface triggers a wakeup of
the PC

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36

Event Management
PerLabUpon inactivity timer expiration
close all TCP connections
enter sleep state

If (count of connected peers < max_connect)
randomly selected peer in my peer list
send wake-up message to peer p
try to connect to peer pif (TCP connection established)
then p.state = connected
else remove peer p from my peer list
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37

Event Management
PerLabUpon receiving a wakeup message from peer pif (TCP connection is established from peer p)then my.state = connected
send my file contents bit-field to peer p
run choking algorithm

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38

Simulation Setup
PerLabNS-2 simulation tool
Single swarm
50 peers (a typical large swarm)
one additional initial seed peer (never sleep in any of the cases)

max_connect =5File size =1 GB (small video file)
Upload data rate = 2 Mbps
Download data rate = 10 Mbps
Wake-up/Sleep transition time = 300 ms
Peer inter-arrival time = Poisson
0, 0.5, 1, 2, 4, 8, 16, 32 msec

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39

Energy Consumption
PerLabLegacy BitTorrent

Green BitTorrent

Energy Savings = 77.8%
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40

Increase in the Download Time
PerLabEnergy Efficient BitTorrent for Green P2P File Sharing

41

41

Limits of Green BitTorrent
PerLab

Green BitTorrent relies on magic packets to
wakeup sleeping peers
This mechanism may not be available on some NICs

Privacy/security issues
A remote peer is able to know whether your PC isactive or sleeping
A malicious user could wake up your PC, just to
increase your energy consumption
An attacker could sleep and wake up your PC with ahigh frequency to damage your hardware

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42

Proxy-based
BitTorrent

43

EE-BitTorrent
PerLabProxy-based version of BitTorrent
One BitTorrent Proxy for a large number of peers(PCs)

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44

Architecture
PerLabBT Peer
TCP/IP
EE-BT Daemon
BT Peer
EE-BT

EE-BT

ClientServer

TCP/IP

TCP/IP

BT Peer

BitTorrent Overlay Network

TCP/IP

TCP/IP
BT Peer
TCP/IP

User’s PC

BitTorrent Proxy

BitTorrent Overlay Network

EE-BitTorrent (EE-BT)
Clients and Proxy (clients side)
Client/Server scheme

Traditional BitTorrent (BT Peer)
Proxy (P2P Network side)
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45

EE-BT Protocol – version 1
PerLabUser's PC

Torrent Server

BitTorrent Proxy

BitTorrent Overlay(1) GET .torrent file(2) PUT .torrent file(3) DOWNLOAD filename(5) Switch off(4) ACK(6) fi
le

down
load
requ
est

ATA
(7) D

ATA
(7) D

(9) CHECK filename(8) Switch on(10) STATUS filename(11) GET filename(12) PUT filename

Energy Efficient BitTorrent for Green P2P File Sharing

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46

EE-BT Protocol – version 2
PerLabUser's PC

Torrent Server

BitTorrent Proxy

BitTorrent Overlay(1) GET .torrent file(2) PUT .torrent file(3) DOWNLOAD filename(5) sleep(4) ACK(6) fi
le

down
load
requ
est

ATA
(7) D

ATA
(7) D

(8) MAGIC PACKET(9) wakeup(10) PUT filename

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47

Implementation
PerLabEnergy Efficient BitTorrent modules
Client – Server scheme
Server (Proxy)
Client (user PC)

Programming language: Python
Libtorrent Rasterbar: library for BitTorrent
Command-line BitTorrent client
Energy Efficient BitTorrent for Green P2P File Sharing48

48

Where to place the BitTorrent Proxy?
PerLab

Departmental Scenario
Dedicated Machine
Machine already used for some other services
Better control (in addition to energy efficiency)

Residential Users
Several Options
Provided (for free) by ISP
Cloud Proxy leased to users
Proxy maintained and shared by a group of users (Social Proxy)

The proxy should have a high-speed connection
The proxy should be as close as possible to users

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49

Performance metrics
PerLab

Relative Energy Saving
Assumptions

EP
S = 1−EL

All PCs and proxy have the same power consumption

Susr (n) = 1 −D (i ) + Dt (i )DP (i )= 1− rDL (i )DL (i )nn

S sys ( n) = 1 − i =1

i =1n

∑ Do (i ) + ∑ [Dr (i ) + Dt (i )]∑ D (i )i =1Energy-efficient BitTorrent for Green P2P File Sharing

L

50

50

Dept. Scenario
PerLabEthernet LAN
Both the proxy and peers are connected to the same LAN
100 Mbps

Downloaded files
Size: ~4GB [3.95 GB – 4.71 GB]
Initial number of seeds: 200 – 800

Methodology
Interleaved experiments with Legacy BitTorrent and Proxy-based
BitTorrent
Experiments replicated several times per day and in different days

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51

Relative Energy Savings
PerLabEnergy Savings (%)

100
80
60
40
20

Dedicated Machine
Multi-server Machine

0
-20
1

2

3

4

5

6

Number of PCs

Energy Efficient BitTorrent for Green P2P File Sharing

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52

Residential Scenario
PerLabADSL Access Network
Downlink rate:
Uplink rate:

up to 8 Mbps
up to 512 Kbps

Users
Up to 4 different users, at different locations
A, B, C, D

File Types:
135 MB (Audio CD, MP3)350 MB (Episode of a TV Series, AVI)
4 GB (Ubuntu 10.10 Distribution, ISO)

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53

Single User at Location A
Average Download Time (h)PerLab8
6Legacy (PC)Proxy-based (Proxy)
Proxy-based (PC)

1.6 hProxy fromoveraly42
0
100 MB

350 MB

4 GB

File Size
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54

Single User at Location B
Average Download Time (h)PerLab2,0
1,5Legacy (PC)Proxy-based (Proxy)
Proxy-based (PC)

1,0
0,5
0,0
100 MB

Energy Efficient BitTorrent for Green P2P File Sharing

350 MB
File Size

4 GB

55

55

Why a so different performance?
PerLabSame nominal uplink/downlink rates
512 Kbps, 8 Mbps

Very different actual uplink rate
The actual uplink rate at A is significantly lower thanthat experience at B

Tit-for-tat penalizes users with low uplink rate
In the proxy-based version the download time only
depends on the downlink rate
Location

LegacyEEEE-BitTorrent

A

0.89 Mbps

2.86 Mbps

B

6.66 Mbps

6.18 Mbps

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56

Single User
PerLabEnergy Consumption
Susr (n) = 1 −Dr (i ) + Dt (i )DL (i )n

S sys (n) = 1 −BitTorrent Overlay
User’s PC

time

DL

n

∑ D (i ) + ∑ [D (i ) + D (i )]
i =1

o

r

i =1
n

t

BitTorrent Overlay
BitTorrent Proxy
User’s PC∑ D (i )
i =1

DL

Do
Dr

Dt

time

L

Location

Susr (1)S sys (1)

A

25,4%

-52,1%

B-16,8%-147,3%

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57

Energy Savings
PerLabUser and System Energy Savings

Location

A

1 PC

2 PCs

3 PCs

4 PCs

25.4%

41,8%

33,2%

28.8%

-52.1%

-1,2%

0,8%

4.8%

B
Susr

-16.8%-14.5% -19.1%-19.8%

B
S sys-147.3%

-1.2%

0.8%

4.8%

A
Susr

S sys

B

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58

Lessons learned in residential scenarios
PerLab

The available uplink rate strongly depends on thespecific location
For a given location it also vary significantly over time

EE-BitTorrent outperforms the legacy BitTorrent
when the available uplink rate is low
Otherwise, the legacy BitTorrent is the moreconvenient approach
Selecting a priori the most convenient option isalmost impossible
Adaptive BitTorrent (AdaBT)
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59

AdaBT: Basic Idea
PerLabGoal
Choosing the most convenient option, depending on
the operating condition at run time

Upon receiving a request for a file
Estimates the time required for downloading the filefrom the BitTorrent overlay (legacy BitTorrent)
from the configured BitTorrent Proxy

Selects the most convenient option

When using EE-BitTorrent
If file already available, starts download
Otherwise, switches off and reconnects later
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60

AdaBT: Algorithm
PerLab1 AdaBT_start_time = time();2aStart Legacy BitTorrent; Wait for the first chunk of data;

3aLegacy_start_time=time();4a

Wait for Q data;

5aLegacy_end_time = time();6a

TL=Legacy_end_time-Legacy_start_time

7a

RL=Q/TL

2b

request S data from Proxy;3b

Proxy_start = time();4b

Wait for Q data;

5b

Proxy_end_time = time();6b

TP=Proxy_end_time-Proxy_start_time

7b

RP=Q/TP8

AdaBT_end_time=time();9

TOH = AdaBT_end_time-AdaBT_start_time;10

if (L/RP+TOH) < α∙((L-Q)/RL)) then use EE-BitTorrent

11

else use legacy BitTorrent;// estimated rate with legacy protocol// estimated rate from proxy

Energy Efficient BitTorrent for Green P2P File Sharing

Giannetti, G. Anastasi, M. Conti
Energy-Efficient P2P File Sharing for
Residential BitTorrent Users
Proc. IEEE International Symposium on
Computers and Communications (ISCC 2012),
Cappadocia, Turkey, July 1-4, 2012.
61

61

AdaBT: Experimental Results
PerLabFile size = 4 GB

Location A

Location B
4

AdaBT
Alternative Option

P

6

4

2
P

P

0
100 MB

350 MB
File Size

4 GB

Energy Efficient BitTorrent for Green P2P File Sharing

Average Download Time (h)Average Download Time (h)

8

AdaBT
Alternative Option

3
2
P

L

1

P

L

L

L

P

L

L

4

5

6

7

8

9

10

L

0
1

2

3

Number of experiment

62

62

Summary
PerLabEnergy Efficiency in BitTorrent
EE-BitTorrent
Proxy-based solution

Implementation

Experimental Analysis
In a dept. scenario EE-BitTorrent provides a significant
reduction in energy consumption
In a residential scenario performance is strongly
influenced by the available uplink rate

AdaBTadaptive solution that dynamically selects the mostconvenient option, based on operating conditions
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63

BitTorrent with
Download Sharing64

Overview
PerLabMainly targeted to unpopular files
File for which there is a limited number of available
copies (i.e., seeders)

Basic idea
Aggregate downloads on intermediate active leechersand hibernate the other leechers (passive leechers)

Comparison with proxy-based BitTorrent
The download is delegated to another peer (active
leecher)
The active peer is not a dedicated machine
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65

Download of Unpopular Files
PerLabVery few seeders
Each seeder serves
one or more leechers
P2P degenerates toclient-server
Low performance
It could be convenient
to aggregate theupload capacity ofseeders

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66

Download Sharing
PerLabEnergy Efficient BitTorrent for Green P2P File Sharing

67

67

Download Sharing
PerLabA random subset is selected to serve as active
leechers
The leechers with the fastest link to seeders should beselected
All the other leechers are hibernated (passive leechers)

Active leechers serve as proxies for passive
leechers
Once the downloads are completed, files are transferred
to passive leechers
It is assumed that active and passive leechers are close toeach other (e.g., neighboring homes)
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Dowload Sharing
PerLabState cycle of a leecher

P=Passive
A=Active
AB=Active Blocked
ABC=Active-Blocked-Content

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Simulation Environment
PerLab

N leechers

Aggregate Load

Load=avg. number of tasks per week per leecher

Bd= Downlink Bandwidth
Bu= Uplink Bandwidth
Bl= Download rate achieved with legacy BitTorrent
Unpopular files
Assumed equal to 300 Kbps

Service time = 8 hours
Simulation time = 1 year

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Download Sharing
PerLab

N=1000 leechers
Bl=300 Kbps

Energy Efficient BitTorrent for Green P2P File Sharing

Legacy BitTorrent

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71Remarks on Download Sharing
PerLabTargeted to unpopular files
For which Bl is typically low

Uses a proxy-based approach
Active Leechers act as proxies for passive leechers

Efficient only when Bu >> Bl
More suitable for future residential access networks
Currently Bd > Bu
The transfer rate from the active leecher to the passive
leecher is limited by the downlink bandwidth of the latter

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Conclusions

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Conclusions
PerLabEnergy Efficiency in the Internet
At the user side

Energy efficiency in P2P File Sharing
BitTorrent

Energy Efficient BitTorrent
Green BitTorrent
Proxy-based BitTorrent
Download Sharing

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PerLabThank you for your attention!
Questions?

Email: ilaria.giannetti@iet.unipi.it

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