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The objective of my thesis research. Performance evaluation of TCP protocol over a Geo satellite link Rating the Bit Error (BER) over this satellite link Performance evaluation in the file transfer over satellite link on Microsoft operating systems (Windows 98, 2000, NT 4.0)
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The objective of my thesis research • Performance evaluation of TCP protocol over a Geo satellite link • Rating the Bit Error (BER) over this satellite link • Performance evaluation in the file transfer over satellite link on Microsoft operating systems (Windows 98, 2000, NT 4.0) • Finding a convenient configuration for the operating systems so as to use the whole available bandwidth
Test platform : asymmetrical satellite link ARTES Multimedia Lab - Holland Centro Elis - Rome Uplink DVB 131.176.20.20 Windows 2000 server 131.176.20.31 Windows NT 195.103.122.45 Windows NT server 131.176.20.30 Windows 98 62.110.204.18 Windows 2000 195.103.122.46 Ethernet 100Mbps Others PC of the network 131.176.20.0 ADSL Link Internet Internet 2Mbps Link Router Cisco 2600 131.176.20.250
Specifications of my testing satellite link DVB-S Decodificator
Tcp problems over high RTT channel (1) • Long time to start a new connection (Three way handshake) • Long Transient of Slow Start
Tcp problems over high RTT channel (2) • Length of time to recover the loss (Fast Retransmit e Fast Recovery)
Tcp problems over high RTT channel (3) • Control flow mechanism Slow-speed link High-speed link
A comparison of the three operating systems default condition 64KB receiver’s window
Throughput with multiple connections and receiver’s advertised window of 64 KB
Conclusions • The 85% link utilization has been achieved by one only flow using the W2k window scale option • 100% link utilization achieved through the use of two concurrent flows • Satellite channel reliability: Viterbi code high rate allows to reach BER lower than10-8 • Since the tested satellite link is QEF (Quasi Error Free), it can be employed for IP multicast transmission saving bandwidth