Optimization algorithms for multipath transfer over asymmetric paths using concurrent multipath transfer stream control transmission protocol
The Internet has evolved in three directions over the past decades. First, content has evolved from relatively low-bandwidth content static text and web pages to highbandwidth content multimedia which results in a significant and growing amount of bandwidth demand. Second, its usage has explosive...
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Main Author: | |
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Format: | Thesis |
Language: | English |
Published: |
2016
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Online Access: | http://psasir.upm.edu.my/id/eprint/69318/1/FSKTM%202016%207%20IR.pdf http://psasir.upm.edu.my/id/eprint/69318/ |
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Summary: | The Internet has evolved in three directions over the past decades. First, content has
evolved from relatively low-bandwidth content static text and web pages to highbandwidth
content multimedia which results in a significant and growing amount
of bandwidth demand. Second, its usage has explosively globalized. Third, Internet
access nature has changed from fixed access through desktop computers to a
mobile access via smart phones and tablets. As a result, the principles of the
Internet design are no longer suitable for current and future applications (e.g.,
mission-critical and time-critical applications). Network resources management is a
key success for the future Internet.
Furthermore, in the last decade hosts have equipped with multiple interfaces.
Clearly, that led to the desire of applying load sharing to utilize all paths
simultaneously to enhance application payload timeliness, and improve resilient to
problems on a particular path.
Readily apparent, Transport layer is the only layer that realizes a path congestion
control and flow control. In addition, a Transport layer that realizes multi-homing
does not require modifying the applications or changing the Network layer
protocol. The Stream Control Transmission Protocol (SCTP) is an emerging multihoming
general purpose Transport layer protocol. An extension of SCTP denoted
as Concurrent Multipath Transfer Stream Control Transmission Protocol (CMTSCTP)
realizes load sharing functionality. This protocol works well for symmetric
paths. But, in reality symmetric paths are unlikely in networks such as Internet.
More, multi-homing offers link failure tolerance at Network layer by using
different access technologies simultaneously to connect through. Different access
technologies clearly imply highly asymmetric paths. CMT-SCTP over asymmetric
paths does not work that neatly.
In this thesis, phenomena affects CMT-SCTP in asymmetric paths are
demonstrated. A comprehensive analysis to understand its nature is presented.
Mechanisms that promote CMT-SCTP performance are implemented and
evaluated in simulation in order to show their effectiveness. In particular, a
combination of multiple mechanisms is vital to make CMT-SCTP works more
neatly under a wide range of network and system parameters.
Intrinsically, retransmission strategy controls retransmission behavior when a
sender fails to receive acknowledgements for sent data due to reorder, lost or
corrupted packets. An efficient retransmission strategy would help to vitiate buffer
blocking. A new retransmission strategy denoted as Rtx-HYBRIDMETRIC takes
into account path’s loss rate and delay is explored. The simulation results show that
Rtx-HYBRIDMETRIC retransmission strategy performs well for both failure and
non-failure scenarios in a real configuration. In addition, Taxonomy for SCTP
retransmission strategies is developed.
More, an accurate ROUND TRIP TIME (RTT) is crucial since it is the core of the
RTO. The RTO must be correctly set to achieve good performance. Interestingly,
CMT-SCTP efficiency is improved by delayed acknowledgement despite
additional delay is introduced. However, delayed acknowledgement may lead to
inaccurate RTT on asymmetric paths. A new strategy called as Immediate SACK
RTT samples (IS-RTT) is developed for accurate RTT on asymmetric paths. The
simulation results show that IS-RTT strategy can significantly optimize the RTT
estimation on asymmetric paths.
Finally, CMT buffer split strategy holds equipoise distribution of buffer space
among asymmetric paths. It reveals tradeoff between giving individual path
application payload throughput guarantees and maximizing application payload
throughput. A new strategy denoted as Quick Response Delayed
Acknowledgement for CMT (QR-DAC) is integrated with buffer split strategy. The
simulation results show that application payload throughput in a real configuration
is optimized over asymmetric paths loss rate. |
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