IEEE 802.11-DS and IEEE 802.11b

Pavel Roskin proski
Sun Jul 18 08:25:10 PDT 2004

On Sun, 18 Jul 2004, Oscar Rodilla wrote:

> Hi to everybody.
> I'm programming a script (executed in the hostap) which obtains the
> channel whith less interferences from other AP's. After this scan, the
> HostAP changes to mode master and starts working in this channel.
> Everything works correctly when the output of a "iwconfig" command shows
> something like that:
> wlan0 IEEE 802.11b mode:  ....
> But sometimes, this output changes to IEEE 802.11-DS and then nothing
> works correctly. When this occurs, the card doesn't accept "iwpriv" or
> most "iwconfig" commands. A solution is restart the card (another time I
> see IEEE 802.11b in the output) but obviously this is not the best way
> because clients connected to hostAP will loose their connection.
> Anybody can tell me why the card changes to IEEE 802.11-DS ?? What does
> it mean ??

It means that the card doesn't support data rates defined in the 802.11b
standard, namely 5.5Mbps and 11Mbps.  Almost all cards should support
those rates.  I'm not sure if HostAP would support old 802.11-DS cards.
And of course the 802.11b support shouldn't change for the same card.

What I think is going on is that something wrong happens to the firmware
and it becomes unable to return the list of data rates.  That's why
prism2_get_name() returns "IEEE 802.11-DS".  I'm quite sure you have
bigger problems if it happens.  Different standard name is just one of the
symptoms you happened to notice.  Perhaps the card indeed needs reset at
this point.  See kernel log for error messages.

By the way, "iwgetid" is preferred over "iwconfig" in scripts.  "iwconfig"
formats data for the end user.

Pavel Roskin

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