Re: Set router to G or B/G?

On Wed, 07 Feb 2007 23:39:35 -0600, Peabody
<waybackNO784SPAM44@yahoo.com> wrote:

>I found this in a Wiki entry on Tomato, a firmware alternative
>similar to DD-WRT:
>
>"B/G Mode: This may be Mixed (B+G), B-Only (restricted to 802.11b),
>or G-Only (restricted to 802.11g). If you set this to B-Only or
>G-Only, connection attempts from the other protocol may be seen as
>interference. Recommend leaving this set to "Mixed"."
>
>I've read somewhere that using both B and G in your LAN will slow
>things down a lot, or at least slow the G devices down a lot. So I
>just assumed that setting the router to G-only would be best. But
>this quote suggests that's not the case.
>
>I've also read somewhere that if there are a number of nearby
>networks, it may be better to be on the same channel with them as
>opposed to being on a different channel where they will be seen as
>interference. Apparently interference slows things down more than
>recognizable competing packets. Is the router setting issue the
>same kind of thing?
>
>If it matters, my router is a Buffalo WHR-HP-G54, and the only
>wireless device on my LAN is a laptop using G.

With the fairly new WHR-HP-G54, I would use Mixed Mode (B+G) unless
you are interested in squeezing every last bit of speed out of the
beast.

According to theory, the older chipsets would take a severe
performance hit in mixed mode. The way they worked was to sample for
"b" clients about 1/4 of the listening time. It varied with chipset
and product. See the table at:
<http://wireless.wikia.com/wiki/Wi-Fi#Performance_and_Speed>
Hmmm.... Looks like the Atheros white paper I referenced has been
moved to:
<http://www.atheros.com/pt/whitepapers/atheros_range_whitepaper.pdf>

However, current chipsets work differently. They still sample for "b"
clients, but vary the listening window and sample rate depending on
whether they hear any "b" traffic, or if any "b" client associates. If
they do, then the aformentioned slowdown still happens. However, if
there are no "b" clients around or connected, then the maximum "g"
speeds can almost be achieved. Methinks this is a good compromise
although it does seem to have a detrimental effect on the time it
takes for a "b" client to associate.

Where the Mixed Mode (B+G) causes problems is with wireless video. The
intrusion of a "b" client will slow things down and possibly break any
attempt at streaming.

An open question is whether it is necessary for a "b" client to
actually connect to the wireless router to slow things down, or if
just a few "b" packets in the vicinity can cause problems. I don't
know the answer but will make an attempt to find out (when I have
time) as it's something I've been wondering about. The older chipsets
only required one lousy "b" packet to slow things down. Hopefully,
with the newer chipsets, Broadcom did something smarter.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS