Multiple Path Connection through a Set of Connection Relay Servers

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

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Outline of the Talk

• Background and Motivation
• Related Work
• MPC-CRS
• Performance of MPC-CRS
• Lessons learned
• Future work

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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

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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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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Multipath Routing

• Single path Vs. Multiple paths

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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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Available Multipath Solutions

• Data Link Layer
• Network Layer
• Transport Layer
• Parallel download from multiple mirror sites

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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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Network Layer

• Network Layer
• Table-driven algorithms
• Source Routing
• Multi Protocol Label Switching (MPLS)

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Transport Layer

• Transport layer
• (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.

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Parallel Download from Multiple Mirror Sites

• History-based TCP parallel access
• Dynamic TCP parallel access

Ref http//research.microsoft.com/pablo/paraload
.aspx
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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 receivers
  operating system network related code

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Bit Torrent

• Popular P2P file distribution system
• 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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Limitations With Current Solutions

• Hardware dependent
• Platform dependent
• Complex to setup and configure
• Changes to end points

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Proposed Solution

• Multiple Path Connections using Connection Relay
  Servers - MPCCRS

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Requirements

• Provide multiple path data transmission
• Hardware independent
• Platform independent
• Easy and Quick to setup
• Compatible with current internet infrastructure

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Architecture
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Implementation

• Client Communication
• Set client to forward requests to client proxy

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Clientproxy Communication

• Check in cache
• Create MD5 digest
• Forward request to SP
• Wait for client collector response

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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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CRS and Bandwidth Relay Server Communication
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Client Collector Communication

• Collect packets
• Assemble data bytes
• Store complete data
• Communicate with client proxy

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Packet Data

• Application data
• Byte range
• File name
• Packet number
• Connection status

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(No Transcript)
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Testbed Machines
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How Data Collected

• Multiple sizes of data
• 1,2, 3 paths

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End-to-End Response Time
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File Size Vs. Avg. Transfer Rate
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Client Collector Processing Time
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Client Collector Average Process Rates
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CRS Average Process Times
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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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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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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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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.
  2004.
• 3 C. Casetti, et. al., "TCP Westwood
  End-to-End Congestion Control for Wired/Wireless
  Networks", In Wireless Networks Journal 8,
  467-479, 2002
• 4 S. Bohacek, et. al. A New TCP for Persistent
  Packet Reordering, In Transactions on
  Networking, 2004.