1. Multiple Path Connection through a Set of Connection Relay Servers
Master Thesis Presentation
Syama S Kosuri
Department of Computer Science
Univ. of Colorado at Colorado Springs
11/23/2018

2. Outline of the Talk Background and Motivation Related Work MPC-CRS
Performance of MPC-CRS
Lessons learned
Future work
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3. Internet Explosion Started with ARPANET in 1969.
Factors contributing to explosion
multimedia
P2P applications
Impact
Poor application performance
Congested networks
Frequent break-downs
Forecasted traffic by 2007 – 5175 peta bits [IDC]
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4. Obvious Solution
Upgrade or add new network infrastructure to meet the growing demand
Then what is the problem?
A very costly affair
Time consuming too…
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5. What Is the Alternative?
Devise methods to make use of the available bandwidth effectively
What is the effective bandwidth of a network?
– Lowest bandwidth of all links in a network
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6. Multipath Routing
Single path Vs. Multiple paths
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7. Advantages Of Multipath Routing
Increased network performance
Application can use the paths that best suit its needs
Aggregate path resources
Improved security
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8. Available Multipath Solutions
Data Link Layer
Network Layer
Transport Layer
Parallel download from multiple mirror sites
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9. Data Link Layer
combining multiple physical network links between two devices into a single logical link for increased bandwidth
Taken from - Yu Cai, "On Proxy Server Based Multipath Connection", PhD dissertation, UCCS, 2005
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10. Network Layer Network Layer Table-driven algorithms Source Routing
Multi Protocol Label Switching (MPLS)
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11. Transport Layer Transport layer: TCP congestion control
(parallel) pTCP [1 ]: subflow control via SM (stripped manager) and TCP-v (virtual); no UDP support.
(multiple) mTCP [2]: subflow control – a TCP subflow on each path; one-way only; no UDP support.
TCP congestion control
TCP Westwood [3]: use measured “residual bandwidth” instead of 1/2 * cwnd in fast retransmit and slow start.
TCP-PR [4]: use a TCP timer for TCP persistent reordering problem.
mTCP from Larry Peterson from Princeton on Usinex04
pTCP from GIT on ICNP02
Westwood from UCLA
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12. Parallel Download from Multiple Mirror Sites
History-based TCP parallel access
Dynamic TCP parallel access
Ref:
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13. Work at UCCS Proxy Server based Multipath Connection (PSMC)
Yu cai and Frank watson
Data striping was implemented at the IP layer
Data reassembly using double buffer for TCP
Allows support for TCP and UDP
Cons
TCP persistent reordering problem in multipath environment.
TCP packets are likely to reach destination out of sequence number, which cause serious performance degradation.
Solution is to implemented a double buffering scheme on TCP layer
Need to change the sender and receiver’s operating system network related code
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14. Bit Torrent Popular P2P file distribution system Pros Cons
File is broken down to pieces (~ 1MB)
Fragments are downloaded from peers
Packets are reassembled on the client side.
Pros
Faster downloads
No server congestion
Cons
Multiple peers should have same file!!
Legal issues
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15. Limitations With Current Solutions
Hardware dependent
Platform dependent
Complex to setup and configure
Changes to end points
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16. Multiple Path Connections using Connection Relay Servers - MPCCRS
Proposed Solution
Multiple Path Connections using Connection Relay Servers - MPCCRS
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17. Requirements Provide multiple path data transmission
Hardware independent
Platform independent
Easy and Quick to setup
Compatible with current internet infrastructure
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18. Architecture
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19. Implementation Client Communication
Set client to forward requests to client proxy
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20. Clientproxy Communication
Check in cache
Create MD5 digest
Forward request to SP
Wait for client collector response
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21. Serverproxy Communication
Calculate Bandwidths of available paths when started
Create MD5 digest
Select service paths
Fill in packets and send data
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22. CRS and Bandwidth Relay Server Communication
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23. Client Collector Communication
Collect packets
Assemble data bytes
Store complete data
Communicate with client proxy
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24. Packet Data Application data Byte range File name Packet number
Connection status
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25. 11/23/2018

26. Testbed Machines Proxy server Physical Machine Client Proxy
NCDCRX1.UCCS.EDU
Server Proxy
VINCI.UCCS.EDU
Client Collector
Connection Relay Server1
BLANCA.UCCS.EDU
Bandwidth Relay server1
Connection Relay Server2
CRESTONE.UCCS.EDU
Bandwidth Relay server2
Connection Relay Server3
SANLUIS.UCCS.EDU
Bandwidth Relay server3
Client
Mozilla web browser
Web Server
CS.UCCS.EDU
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27. How Data Collected
Multiple sizes of data
1,2, & 3 paths
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28. End-to-End Response Time
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29. File Size Vs. Avg. Transfer Rate
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30. Client Collector Processing Time
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31. Client Collector Average Process Rates
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32. CRS Average Process Times
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33. Lessons Learnt
It took good amount of time figuring out how to synchronize between the two streams of data
Management of shared resources is complicated.
Lot of time was spent on understanding HTTP protocol
Learnt and used lot of socket programming
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34. Future Work
Extend MPC-CRS to run applications using multimedia/streaming protocols
Establishing security and trust between proxy and CRS servers
Efficient way to place the servers across the internet to take full advantage of MPC-CRS
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35. Contribution Studied existing multipath systems
Identified limitations of existing systems
Built a multipath system that overcomes existing limitations
Architecture and design
Implementation
Performance testing
Documented results
Proposed areas of future work
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36. Additional References
[1] H. Hsieh, et. al., “ptcp: An end-to-end transport layer protocol for striped connections”, In Proceedings of IEEE ICNP, 2002.
[2] M. Zhang, et. al., “A Transport Layer Approach for Improving End-to-End Performance and Robustness Using Redundant Paths”, In Proc. of the USENIX 2004 Annual Technical Conference
[3] C. Casetti, et. al., "TCP Westwood: End-to-End Congestion Control for Wired/Wireless Networks", In Wireless Networks Journal 8, , 2002
[4] S. Bohacek, et. al. “A New TCP for Persistent Packet Reordering”, In Transactions on Networking, 2004.
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