Re: 802.11 stuff

On Mon, 13 Jul 2009 20:24:31 +0200, hlexa@xxxxxxxxxxx (Axel
Hammerschmidt) wrote:

Jeff Liebermann <jeffl@xxxxxxxxxx> wrote:

On Mon, 13 Jul 2009 18:01:44 +0200, hlexa@xxxxxxxxxxx (Axel
Hammerschmidt) wrote:

<snip>

<http://users.cybercity.dk/~dsl487543/Protection.png>

Trendnet TEW-510APB, 802.11a/b/g, with B/G mode usualy turned off.

Perhaps I'm a bit dense this morning, but I don't see anything on that
page that looks like an 802.11b protection on/off switch. The only
item which seems involved is "Allow 54Mbs Stations Only" which seems
rather vague. Does it turn off 5.7GHz? Does it disable speeds above
54Mbits/sec? Does it lock the router to 54Mbits/sec as the only
speed? Got a clue what it means? It's kinda academic as you have it
disabled.

What's your question got to do with 802.11g 802.11b protection?

Why does asking you a question usually result in another question
instead of an answer? I guess I'm doing the same thing. Do like I
say, not like I do.

I was assuming that your mysterious "manual switch" was the "Allow
54Mbps Stations Only" setting (which you incidentally have disabled).
The wording is a bit unusual and I thought that since you have the
unit, have done extensive testing, and have possibly RTFMed, you might
know what it really means.

However, I did make a bad guess. 802.11b compatibility is only an
issue at 2.4Ghz, not 5.7GHz, so the setting does kind sorta make sense
if "54Mbps stations only" really means "use 802.11g only".

So, where is the disable 802.11b compatibility mode "manual switch"
you previously mentioned? Did I miss something (possibly on a
different web page)?

The switch on the fourth-, third- and second bottom line turn off
802.11g 802.11b protection, until 802.11b traffic is detected. Depending
on how the switch on fifth bottom line is set. The choice is between
different methods.

I don't think so. Most of that is CTS/RTS "protection", not 802.11b
protection. It protects against collisions caused by hidden nodes
(where multiple clients can't hear each other and therefore tend to
transmit simultaneously). At least that's what I think it means.

Below is another example, from the (CD-) manual for my ASUS WL-330gE
multi-function pocket router:

"Wireless Mode

This field indicates the 802.11g interface mode. Selecting "Auto" allows
802.11g and 802.11b clients to connect to the ASUS 802.11g AP. Selecting
"54g Only" maximizes performance, but prevents 802.11b clients from
connecting to the ASUS 802.11g AP. If "54g Protection" is checked, GMode
protection of 11g traffic is enabled automatically in the presence of
11b traffic."

Ok. Now I see. Your "manual switch" is really a setting which
completely disables 802.11b connectivity. Different router, different
names, different description, but probably the same thing.

However, the original problem was over how an access point actually
handles mixed 802.11b and 802.11g clients. I don't see anything that
affects this except to totally ignore 802.11b clients. (Don't assume
that I know how your chipset does this. I'm a few years out of date).

As I read the last part, considering that 802.11b protection on 802.1g
devices is required - see earlier posts, it means that "54g Protection"
will be on all the time when not checked.

This is the first time I've ever heard it refered to as "54g
protection". However, I must admit that it sounds better than
"Disable 802.11b mode".

Can't you read AYBABTU?

<http://en.wikipedia.org/wiki/All_your_base_are_belong_to_us>
In the distant past, I used to work for Standard Communication in
Wilmington CA. We sold VHF/UHF marine and land mobile radios. I
still have many of the manuals that were first written in Japanese,
and then translated into what they considered to be English. SCC
hired a full time technical interpreter to clean up the mess. For the
few that I helped re-write, it was easier to start from scratch.
Direct translations of idioms were the major problem. I don't think I
would do any better translating my English into Japanese.

Here's another one, from my routers firewall.

"If checked, the undefined item in IP Address list is allowed to access
Internet;Unchecked means reverse."

Yech, but typical. A friends son is currently doing classes in
Chinese at Humboldt State. He now talks and writes like that. There
seems to be a cultural thing against being specific or fortifying a
statement with a redundant statement. I do it conciously by avoiding
the word "it" unless it's clearly defined (or doesn't matter). That's
apparently not the case in Chinese, where brevity seems to be
desireable. It also reminds me of some student papers.

I'll do the jperf benchmark test for 802.11b compatibilty sometime
this week, after I drag home an 802.11b only client radio (WAP11). I'm
curious how different routers respond.

--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.

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