On Mon, 16 May 2005 23:15:15 GMT, "bumtracks" <(E-Mail Removed)>
wrote:
>so I look at the dumeter on the xp laptop and it says 6 mega bytes
> is that really 48 megabits
> and is that the limitation of the laptops slow hard drive
Dumeter will work:
http://www.dumeter.com
I don't think it's the hard disk. However, I can't tell without a
complete hardware description. The easiest test is to just time
copying a big file from the hard disk to another part of the hard
disk. Make sure it's big enough to fill up the 2-8Mbyte cache found
in most hard disk. The seek time for the drive will slow things down,
but hopefully not too badly. I can time a few laptops in the office
if you want a comparison basis.
The DWL-2000AP+ will do 54Mbits/sec maximum connection speed. You
won't get anywher near that good a thruput. The theoretical maximums
are:
This is stolen from an Atheros PDF at:
http://www.atheros.com/pt/atheros_range_whitepaper.pdf
with some additions and corrections by me.
Non-overlapping Modulation Max Max Max
Channels ------- | Link TCP UDP
| | | | |
802.11b 3 CCK 11 5.9 7.1
802.11g (with
802.11b) 3 OFDM/CCK 54 14.4 19.5
802.11g only 3 OFDM 54 24.4 30.5
802.11g turbo 1 OFDM 108 42.9 54.8
802.11a 13 OFDM 54 24.4 30.5
802.11a turbo 6 OFDM 108 42.9 54.8
The paper claims that encryption is enabled for these calculations,
but my numbers seem to indicate that these number are for encryption
disabled. Dunno for sure. The Max TCP and Max UDP are the
theoretical maximum thruput rates.
In theory, your 48Mbits/sec is impossible for a 54Mbit/sec connection
as 30.5 for UDP and 24.4 for TCP are the maximum speeds. Does your
access point have "turbo" support to 108Mbits/sec? The UK firmware
page doesn't show if this was added. The DWL-2000AP+ is not sold in
the USA.
The 48Mbits/sec might also be limited by a half duplex 100baseTX
connection between the laptop and the DWL-2000AP+. I can't tell from
the specs if the DWL-2000AP+ is half duplex or full duplex on the
ethernet port. If half duplex, you'll be stuck with about 50Mbits/sec
maximum on the ethernet port. With full duplex, you might get up to
wire speed at perhaps 85Mbits/sec.
There are other things that really affect performance. TCP requires
acknowledgements, while UDP does not. You'll get much better thruput
testing with UDP than with TCP. There are some things you can do to
optimize and improve the efficiency of the TCP/IP stack.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice
http://www.LearnByDestroying.com
#
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#
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