Networked speeds

I have 3 XP Pro machines. Two are connected by LAN cables and communicate
at 100 mbps while the third is wireless at 54 mbps. I moved a 700 meg file
from one LAN connected pc to the other LAN connected pc. It took two
minutes.

I then moved the same file to the wireless pc assuming 4 minutes. However,
the time to completion was well over 4 minutes. I know that network speeds
fluctuate, but any thoughts why it took substantially longer then 4 minutes
to complete.

Thank you

On Sun, 06 Nov 2005 21:18:26 GMT, "-------------------"
<(E-Mail Removed)> wrote:

>I have 3 XP Pro machines. Two are connected by LAN cables and communicate
>at 100 mbps while the third is wireless at 54 mbps. I moved a 700 meg file
>from one LAN connected pc to the other LAN connected pc. It took two
>minutes.
>
>I then moved the same file to the wireless pc assuming 4 minutes. However,
>the time to completion was well over 4 minutes. I know that network speeds
>fluctuate, but any thoughts why it took substantially longer then 4 minutes
>to complete.

You might want to disclose how long it took so we can calculate your
actually transfer speed.

The best you can do with a 54Mbit/sec connection is about 25Mbits/sec
transfer speed. If your 100Mbit/sec PC's are setup for 100baseTX-FDX
(full duplex) you should get about 80Mbit/sec. That's about 3 times
faster than the maximum wireless speed.

However, reality and maximum wireless speeds are quite different. My
guess(tm) is that you're getting much less than 25Mbits/sec. For
example, if you have 802.11b compatibility enabled, your maximum
transfer speed will be about 14Mbits/sec or almost 6 times slower. If
you have any interference, or your connection speed is less than
54Mbits/sec, the numbers will decrease proportionally.

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. I don't have numbers for the
various Turbo and SuperG modes.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]

In <(E-Mail Removed)> on Sun, 06 Nov 2005 18:28:26
-0800, Jeff Liebermann <(E-Mail Removed)> wrote:

>However, reality and maximum wireless speeds are quite different. My
>guess(tm) is that you're getting much less than 25Mbits/sec. For
>example, if you have 802.11b compatibility enabled, your maximum
>transfer speed will be about 14Mbits/sec or almost 6 times slower. ...

Just enabled? I've gotten much better than that.

--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>

On Tue, 08 Nov 2005 01:45:13 GMT, John Navas
<(E-Mail Removed)> wrote:

>[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
>
>In <(E-Mail Removed)> on Sun, 06 Nov 2005 18:28:26
>-0800, Jeff Liebermann <(E-Mail Removed)> wrote:
>
>>However, reality and maximum wireless speeds are quite different. My
>>guess(tm) is that you're getting much less than 25Mbits/sec. For
>>example, if you have 802.11b compatibility enabled, your maximum
>>transfer speed will be about 14Mbits/sec or almost 6 times slower. ...
>
>Just enabled? I've gotten much better than that.

Sigh. Typo or idiot error. 25/14 = 1.8 times slower. Thanks.

The actual speed loss is dependent on the presence of an 802.11b
signal. If there is only the access point and client running 802.11g,
the access point will sniff for 802.11b packets very infrequently. The
last time I measured it with WRT54G v1.1 resulted in a max speed of
about 20Mbits/sec. However, when I fired up my 802.11b Orinoco Silver
on my laptop, but generated no traffic, the thruput dropped to about
12Mbits/sec. When I generated a little traffic on the Orinoco with
pings, the thruput dropped to about 10Mbits/sec. I'm not sure this is
consistant among all access points as I only tested this one.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558