Re: File Transfer Speeds

From: SIMON HART (simon.hart@btinternet.com)
Date: Tue Apr 12 2005 - 08:32:46 GMT-3


Wayne,
 
Throughput is not only determined by available bandwidth, but through the characteristics of TCP.
 
The URL below takes you to a very infomative website that will explain how TCP window sizes, bandwidth and latency all interact to effect throughput. It also has a very useful spreadsheet for working out throughput.
 
http://www.babinszki.ca/Networking/#PERF-MODEL
 
HTH
 
Simon

Wayne Bellward <wbellward@gmail.com> wrote:
Hi All,

I have two 3550EMI's connected via a 10Mb Full duplex crossover, the
link is a 802.1q trunk and I only have about four VLANS running. When
I do an FTP of a 10Mb binary file between two hosts one on each switch
in different VLANS I get file transfer speeds of about 50KBs. If I
put the hosts on the same 3550 I get transfer speeds of about 85KBs,
CEF is enabled but either way I would expect to get transfer speeds
much greater than those I am getting.

The 3550 has a 8.8Gbps switch fabric and a throughput of 4.4Gbps can
anyone explain to me why this is happening? I don't think there is a
problem with the switches or the hosts but get the impression I am
missing a fundamental aspect of switching.

Many Thanks,

Wayne



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