Media-Friendliness of a Slowly-Responsive Congestion
Essay by review • December 15, 2010 • Term Paper • 4,162 Words (17 Pages) • 2,216 Views
Media-Friendliness of A Slowly-Responsive Congestion
Control Protocol
Zhiheng Wang
Dept. of EECS
University of Michigan
Ann Arbor, MI 48109
Sujata Banerjee
Internet Systems & Storage Lab
Hewlett-Packard Laboratories
Palo Alto, CA 94304
Sugih Jamin
Dept. of EECS
University of Michigan
Ann Arbor, MI 48109
ABSTRACT
Streaming media transfers over the Internet are expected to behave
in a TCP-friendly manner while reacting slower to congestion than
TCP. For this purpose, a number of slowly-responsive congestion
control protocols have been developed. In this paper, we present
our study on the media-friendliness of TFRC, one of the recently
developed slowly-responsive congestion control mechanisms. With
both simulation and Internet experiments, we show that TFRC is
not necessarily smooth enough to be "media-friendly". We also
discuss our approach to improve a congestion control mechanism's
media-friendliness.
Categories and Subject Descriptors
C.2.2 [Computer-Communication Networks]: Network Protocols
--Protocol Verification
General Terms
Performance, Design
Keywords
TCP-Friendly congestion control, performance evaluation
1. INTRODUCTION
With emerging advanced technologies on both end hosts and network
connections, the deployment of multi-media applications over
the Internet has increased rapidly in recent years [1, 2, 3]. Media
content can be disseminated over the Internet through bulk data
transfer or streaming. In this paper we concentrate on streaming
media transfers.
The implication of streaming is that network sending rate must
be closely matched to the data generation rate and the rate at which
the data is consumed by the client application. If these rates do not
match, receiver buffers can overflow or underflow and the end user
perceived media quality can suffer. Most applications have a small
startup buffer at the receiver which is filled before media playout
can begin. This is done to absorb variable network delays to ensure
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continuous playback. For interactive applications, the size of this
buffer must be small to reduce interaction latency.
Currently, wide-spread deployment of high fidelity streaming
media on the Internet is hindered by the best-effort nature of the
networks. Streaming applications using UDP or TCP for data transfer
are under the risk of either overloading network resources or
receiving lower perceived quality [4, 1]. TCP congestion control
interferes with streaming media throughput requirements by introducing
sudden drops in the sending rate when congestion occurs.
A number of slowly-responsive congestion control protocols [5,
6, 7, 8] have been introduced to reduce these sudden fluctuations,
while complying with TCP congestion control principle of avoiding
overloading network resources.Subsequent to these efforts, the
concept of TCP-friendliness [5] was introduced. TCP-friendliness
ensures the compatibility between a proposed protocol and existing
TCP. "A congestion control mechanism is TCP-friendly if it
displays congestion control behavior that, on time scales of several
round-trip times (RTTs), obtains roughly the same throughput
as a TCP connection in steady-state when the available bandwidth
does not change with time" [6]. However, very few previous efforts
on developing TCP friendly protocols have examined whether
they are media-friendly. A congestion control protocol is mediafriendly
if its congestion control behaviors 1) consider the characteristics
of streaming media and 2) provide streaming media with
uninterrupted transport services.
There
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