Dropbox is a cloud storage service that allows users to store and sync files across devices. It has over 100 million registered users who store over 1 billion files daily. Dropbox uses a distributed architecture, with metadata stored separately from file data to improve performance. File data is stored on Amazon S3 for scalability. Dropbox utilizes various networking techniques like TCP optimizations and caching to improve sync speeds and reduce bottlenecks despite limited bandwidth.

1. Inside Dropbox
Julie Kim
kjulee114@gmail.com

2. Table of Contents
• Cloud Storage Service
• What is “Dropbox”?
• Network Features
• Enhance performance
• References

3. Cloud Storage
 Networked online storage
 Data is stored in
virtualized pool of storage
(April 19, 2013 by wikipedia)
 File hosting Services
http://www.fixmypcfree.com/wp-content/uploads/2012/08/cloud.jpg

4. Cloud Storage
 Data access  Limitation of network
 Using up to date IT bandwidth
infrastructure  Privacy
 No tiresome  Hard to predict costs
 scale up, backup,
security, etc.
 Low cost than building
own storage
https://dt8kf6553cww8.cloudfront.net/static/images/firebox_transparent.png

5. DropBox
• Cloud Storage Service provider
• Bring photos, docs, and videos anywhere
https://www.dropbox.com/static/images/syncbox_transparent.png

6. Numbers for Dropbox
• 100M registered Users
(2012.11)
• 1B files saved a day
(2012.11)
https://www.dropbox.com/sh/sf6whlu5dae4869/-PGKcBGWPU/Dropbox%20Logos/Web/png/dropbox-
logotype-vertical-color.png

7. Network Flow
SSL Exchange
Update …
Handshake meta-data
Batch
Process
w/ACKs
Delta
Encoding

8. Network Flow
SSL-Handshake
Batch Process
with acknowledgement

9. Network Features

10. Network Elements
Mutual Complement
Meta-data store File data store
 Independent Datacenter  Amazon EC2 and S3
Dropbox Datacenter Amazon EC2/S3
Meta-data Direct Links
Notifications Client Storage
Web server Back-traces
Event Logs Web storage
API Storage
http://www.gatech.pa/images/icons/database.png

11. Packet Usage

12. Potential Bottleneck
• TCP Start-up Effects
• Sequential Acknowledgments
– The more packets, The more delay

13. HOW TO BOOST UP
PERFORMANCE

14. Lan Sync?
Lan Sync
Lan Sync
Lan Sync
 Speed Syncing
 Immediately Update&Sync
http://4.bp.blogspot.com/-NpkPe_Ffv0k/TWB3uiLhDdI/AAAAAAAAAcw/1UIxBcGWnTM/s1600/lan-tradicional.gif

15. TCP PSH flag
 Fast Transfer
 Immediately Update&Sync
http://packetcrafter.files.wordpress.com/2011/02/tcp.png

16. Related Protocols
• Routing Protocols
– Using on the Internet protocol networks
• BGP (Border Gateway Protocol)
– External Gateway Protocol
– Used at the edge of your network

17. BGP&OSPF
BGP External
OSPF Interial
http://netmonkey.ru/img/mpls/mpls-bgp-between-pe-ce.png

18. Related Protocols
• OSPF
(Open Shortest Path First)
– Interior Gateway Protocol
– Link-state routing
– LSA
• ISIS
(Intermediate System to Intermediate System)
– Interior Gateway Protocol
– Link-state routing
– DB of network topology
http://www.iekucukcay.com/wp-content/uploads/2011/09/dijkstra.gif
http://www.techweekeurope.co.uk/wp-content/uploads/2012/09/shutterstock_98826353.jpg
http://www.techweekeurope.co.uk/wp-content/uploads/2012/01/IPv6-Landscape.jpg

19. Related Protocols
• OSPF
(Open Shortest Path First)
– Interior Gateway Protocol
– Link-state routing
– LSA
• ISIS
(Intermediate System to Intermediate System)
– Interior Gateway Protocol
– Link-state routing
– DB of network topology
http://www.iekucukcay.com/wp-content/uploads/2011/09/dijkstra.gif
http://www.techweekeurope.co.uk/wp-content/uploads/2012/09/shutterstock_98826353.jpg
http://www.techweekeurope.co.uk/wp-content/uploads/2012/01/IPv6-Landscape.jpg

20. Related Protocols
• MPLS
– Multi-Protocol Label Switching
– For high performance telecommunication
QoS&ECN
BottomOfStack
http://www.openflow.org/wk/images/thumb/1/11/Mpls_label_eth_ip.jpg/500px-Mpls_label_eth_ip.jpg

21. Related Protocols
• DWDM
– Dense Wavelength Division Multiplexing
http://blog.zulyusof.com/wp-content/uploads/2010/08/DWDM-functional-schematic.jpg

22. DWDM
TDM
DWDM
http://ids.nic.in/JCES%20TNL%20OCT%202008/DWDM/Slide30(edited).JPG

24. Conclusion
• Cloud storage services is trendy cloud
service, yet.
• It is the result of modern network
technologies integration.
– Fast sync vs. Congestion control
– Support multiple physical layer, etc.
• Performance bottleneck
– TCP handshaking delay
– Large file with chunks and ACKs

25. Q&A

26. http://4.bp.blogspot.com/-0kyKiMfPSH4/T_upI5Rx99I/AAAAAAAAAUs/S-
NxlqCG7zQ/s1600/thanks20a20bunch20rgb.jpg

27. References
• http://en.wikipedia.org/wiki/Cloud_storage
• Dropbox Quick Start
• What is LAN sync?, https://www.dropbox.com/help/137/en
• Idilio Drago, Marco Mellia, Maurizio M. Munafò, Anna Sperotto,
Ramin Sadre, Aiko Pras. Inside Dropbox:Understanding Personal
Cloud Storage Services, ACM IMC’12, November 14–16, 2012
• Caching in theory and practice,
https://tech.dropbox.com/2012/10/caching-in-theory-and-practice/
• http://packetlife.net/blog/2011/mar/2/tcp-flags-psh-and-urg/
• http://compnetworking.about.com/library/glossary/bldef-dwdm.htm
• https://www.dropbox.com/release_notes