802.11b specification

I'd like to look at the specification of the packets that are sent over
802.11b. Specifically the types (data, management etc.) and so on. I
downloaded a so called spec from the IEEE web site, but that was
missing much more than it included, and seems to talk more about the RF
than the data side.

Does any one have a suggestion where I can start?

On 5 Jul 2005 06:28:42 -0700, (E-Mail Removed) wrote:

>I'd like to look at the specification of the packets that are sent over
>802.11b. Specifically the types (data, management etc.) and so on. I
>downloaded a so called spec from the IEEE web site, but that was
>missing much more than it included, and seems to talk more about the RF
>than the data side.
>
>Does any one have a suggestion where I can start?

Base 802.11-1999
| http://standards.ieee.org/getieee802...02.11-1999.pdf
Other 802.11 related standards and updates:
| http://standards.ieee.org/getieee802/802.11.html
You'll also need 802.11a-1999, 802.11b-1999 and 802.11g-2003. It's
all in there. Be prepared to have your brain turn to mush.

Understanding 802.11 frame types:
| http://www.wi-fiplanet.com/tutorials...le.php/1447501
Beacons:
| http://www.wi-fiplanet.com/tutorials...le.php/1492071

802.11 from Microsoft:
| http://www.microsoft.com/technet/pro...9db0bcafd.mspx
Microsoft Wireless Site:
| http://www.microsoft.com/windowsserv...i/default.mspx


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

I could only find parts of the specs on the IEEE site.

The problem is that my association request fails with reason 18
(required rates aren't supported by the station), even though I believe
that they are. The authentication request went through OK first, so I
must be doing something wrong in the association stage. I've put this
into the rates field:

static const unsigned char eleven_b[] = { 3, 2, 4, 11 };

using this type of code:

frame->u.assoc_req.variable[index++] = sizeof(eleven_b);
memcpy(&frame->u.assoc_req.variable[index], eleven_b,
sizeof(eleven_b));

The beacon packets from the (Cisco) Access Point has 4 (i.e. 2Mb)
defined twice, which is strange. I see { 4, 4, 2, 4, 11 }.

-Nigel

Ignore the 3, at the start of the array. I sent you the wrong version.
It should, of course, have read:

static const unsigned char eleven_b[] = { 2, 4, 11 };

-Nigel

Ignore the 3 in the array. I sent you the wrong version. It should, of
course, read:

static const unsigned char eleven_b[] = { 2, 4, 11 };

On 15 Jul 2005 06:55:20 -0700, "(E-Mail Removed)"
<(E-Mail Removed)> wrote:

>I could only find parts of the specs on the IEEE site.

Which parts could you *NOT* find?

The beast comes in 4 parts.
- 802.11 which is 1 and 2 Mbits/sec only.
- 802.11b which extends the array to 3 (Breezecom FHSS) Mbits/sec,
5.5 and 11 Mbits/sec.
- 802.11a which again expands the field to include OFDM rates
from 6 to 54Mbits/sec, and PBCC for 22MBits/sec.
- 802.11g which applies 802.11a specifications to 2.4GHz and adds
an 802.11b compatibility mode.

You'll need all 4 to decode all the possible speeds. In addition,
some of the chip vendors have gone off on their own and added
proprietary modes. They usually default to indicating 54Mbits/sec but
are running faster.

>The problem is that my association request fails with reason 18
>(required rates aren't supported by the station), even though I believe
>that they are. The authentication request went through OK first, so I
>must be doing something wrong in the association stage. I've put this
>into the rates field:
>
> static const unsigned char eleven_b[] = { 3, 2, 4, 11 };
>
>using this type of code:
>
>frame->u.assoc_req.variable[index++] = sizeof(eleven_b);
>memcpy(&frame->u.assoc_req.variable[index], eleven_b,
>sizeof(eleven_b));
>
>The beacon packets from the (Cisco) Access Point has 4 (i.e. 2Mb)
>defined twice, which is strange. I see { 4, 4, 2, 4, 11 }.
>
>-Nigel

I'm going to play ignorant and pretend I don't know how to program.
You might want to look at various open source implimentations on the
Linksys web pile to see how it's done. The first thing I do before I
scribble code is to see how the other guys do it and steal as much as
possible. Maybe that's why I'm such a lousy programmist.
http://www1.linksys.com/support/gpl.asp



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