802.11g data rate drops because of 802.11b

Somebody told me that 802.11g AP's data rate drops even if there is a single
802.11b client. Is it true?
Is there a way around for the "mixed-mode" operation so that 802.11g clients
can still operate at high data rates even if there are one or two 'b'
clients?
Where can I find the supporting documentation?

TIA

BHAM KAL wrote:

> Somebody told me that 802.11g AP's data rate drops even if there is a single
> 802.11b client. Is it true?
> Is there a way around for the "mixed-mode" operation so that 802.11g clients
> can still operate at high data rates even if there are one or two 'b'
> clients?
> Where can I find the supporting documentation?
>
> TIA
>
>

Yes I believe that's true. The way I got around it was to use my old B
access point (connected to the G router) to service the B clients and
had the G router in G-only mode. Worked fine for me.

TP

On Wed, 22 Sep 2004 15:26:25 -0500, in alt.internet.wireless , "BHAM KAL"
<(E-Mail Removed)> wrote:

>Somebody told me that 802.11g AP's data rate drops even if there is a single
>802.11b client. Is it true?

It depends on the AP. Older APs behave as you describe. Newer ones can
segregate the traffic and suffer much less degradation.

>Is there a way around for the "mixed-mode" operation so that 802.11g clients
>can still operate at high data rates even if there are one or two 'b'
>clients?

If your AP supports it.

>Where can I find the supporting documentation?

On the manufacturer's website?
--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt>


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In article <(E-Mail Removed)>,
BHAM KAL <(E-Mail Removed)> wrote:
:Somebody told me that 802.11g AP's data rate drops even if there is a single
:802.11b client. Is it true?

Yup. When even a single 802.11b client is known, then the AP has to
use the 802.11b collision detection timing instead of the 802.11g timing.
The 802.11b collision detection period is fairly long compared to
an 802.11g packet, but you can't use the 802.11g timing in case the
802.11b device just happens to want to talk at that time.

Traditionally, the collision detection happened as part of
*every* packet sent.

:Is there a way around for the "mixed-mode" operation so that 802.11g clients
:can still operate at high data rates even if there are one or two 'b'
:clients?
:Where can I find the supporting documentation?

ieee.org
--
Sub-millibarn resolution bio-hyperdimensional plasmatic space
polyimaging is just around the corner. -- Corry Lee Smith

"Mark McIntyre" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On Wed, 22 Sep 2004 15:26:25 -0500, in alt.internet.wireless , "BHAM KAL"
> <(E-Mail Removed)> wrote:
>
> It depends on the AP. Older APs behave as you describe. Newer ones can
> segregate the traffic and suffer much less degradation.

Any example APs that could handle both modes without hurting the high data
rates of 'g'?

That is correct. The way TP got around it does work.

Tom

On Wed, 22 Sep 2004 15:26:25 -0500, "BHAM KAL"
<(E-Mail Removed)> wrote:

>Somebody told me that 802.11g AP's data rate drops even if there is a single
>802.11b client. Is it true?

So it is written. So it must be. (yes).

>Is there a way around for the "mixed-mode" operation so that 802.11g clients
>can still operate at high data rates even if there are one or two 'b'
>clients?

Yes. You can usually force an 802.11g access point into "802.11g
only" mode. This will prevent any 802.11b client radios from
connecting, but will preserve the higher speeds by literally ignoring
any 802.11b packets.

>Where can I find the supporting documentation?

http://www.tomsnetworking.com/FAQ-48-802+11g-0.php#563
There are some performance graphs on that site showing the effect, but
I couldn't find them.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# (E-Mail Removed)
# 831.421.6491 digital_pager (E-Mail Removed) AE6KS

"BHAM KAL" <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> Somebody told me that 802.11g AP's data rate drops even if there is a single
> 802.11b client. Is it true?
> Is there a way around for the "mixed-mode" operation so that 802.11g clients
> can still operate at high data rates even if there are one or two 'b'
> clients?
> Where can I find the supporting documentation?
>
> TIA

Useful document here

http://www.atheros.com/pt/atheros_range_whitepaper.pdf

BH

On Wed, 22 Sep 2004 17:23:18 -0500, in alt.internet.wireless , "Newsgroups
Nut" <(E-Mail Removed)> wrote:

>
>"Mark McIntyre" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>> On Wed, 22 Sep 2004 15:26:25 -0500, in alt.internet.wireless , "BHAM KAL"
>> <(E-Mail Removed)> wrote:
>>
>> It depends on the AP. Older APs behave as you describe. Newer ones can
>> segregate the traffic and suffer much less degradation.
>
>Any example APs that could handle both modes without hurting the high data
>rates of 'g'?

Any that offers "Nitro" mode. See here:
http://www.wi-fiplanet.com/columns/article.php/2196401

For ex, my SMC 2804 54G unit.
--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt>


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On 22 Sep 2004 21:21:53 GMT, in alt.internet.wireless ,
(E-Mail Removed) (Walter Roberson) wrote:

>In article <(E-Mail Removed)>,
>BHAM KAL <(E-Mail Removed)> wrote:
>:Somebody told me that 802.11g AP's data rate drops even if there is a single
>:802.11b client. Is it true?
>
>Yup. When even a single 802.11b client is known, then the AP has to
>use the 802.11b collision detection timing instead of the 802.11g timing.

This problem has been partially solved. Do a websearch for "11b 11g speed
drop".
--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt>


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