Pseudo_IBSS mode issues

Anand R nganandr at yahoo.com
Wed Dec 22 14:54:48 EST 2004


Hi Jim,
    We figured out how to avoid this issue: We
configure each system to have a unique SSID.

We found out that a node has problems staying in
pseudo_ibss mode (PIM) only if there is another node
nearby that is in the standard Ad-Hoc mode and has the
*same* SSID.

In PIM, even though systems have different SSIDs, they
are able to communicate.

Thanks for your email!

-Anand

--- JAMES KABA <jkaba at sarnoff.com> wrote:

> Anand,
>    I'd love to here other responses, but here's my 2
> cents.
> 
>    I have seen this as well.  For the record, it is
> the cards in 
> pseudo_ibss mode that are "misconfigured," since
> pseudo_ibss is not part 
> of the IEEE 802.11 standard.  (It's a shame, too,
> because this "ad hoc 
> demo mode" is such a useful mode.)
> 
>    The cards are still technically in pseudo_ibss
> mode, (i.e. they 
> aren't generating any management frames), its just
> that they have 
> updated their cell id to the one in the management
> frame they received 
> from the node in "official ad hoc mode."  They can
> talk to other 
> pseudo_ibss nodes that have been similarly
> corrupted, but not to 
> pseudo_ibss nodes who are still in
> cell:00:00:00:00:00:00 and not to 
> nodes in regular ad hoc mode.
> 
>    I think the real fix would be a simple firmware
> fix.  ( if mode == 
> pseudo_ibss then don't listen to management frames.)
>  That is, nodes in 
> pseudo_ibss mode should not create any management
> frames, NOR should 
> they listen to management frames.  If anyone has any
> pull with the 
> firmware driver developers, please ask them for this
> very simple fix!!!
> 
>    I have found that the key to not seeing this
> problem is to never have 
> any nodes with the same ESSID be in anything other
> than ad_hoc mode! 
> The way to do this is to get all your cards into
> pseudo_ibss mode before 
> they are brought up.  --To do this, I use the pcmcia
> cardservices 
> scripts instead of doing this configuration "by
> hand".  If you include 
> these lines in you /etc/pcmcia/wireless.opts file
>     MODE="Ad-Hoc"
>     IWPRIV="prism2_param 4 1"
> you'll be in good shape.  These are the equivalent
> of what you mention 
> below, but they are used to configure the card into
> pseudo_ibss mode 
> before it is actually brought up.
> 
> (Note:  I've only seen this problem while trying to
> bootstrap/debug a 
> new driver or something -- never in "steady state"
> -- so it seems to be 
> pretty reliable.)
> 
> Jim
> 
> Anand R wrote:
> > Hi -
> >   I'm trying to setup an Ad-Hoc network. I'm
> trying to
> > avoid the BSSID-partitioning problem by setting
> the
> > card in pseudo_ibss mode. I'm using the following
> 2
> > commands to do this:
> > prism2_param wlan0 ptype 3
> > prism2_param wlan0 pseudo_ibss 1
> > 
> > I'm assuming these are the commands that I should
> be
> > using to set a card in pseudo_ibss mode. Correct
> me if
> > I'm wrong.
> > 
> > The commands work fine if all the nodes within
> radio
> > range are also in pseudo_ibss mode. But if there
> is
> > some other node nearby with the same SSID, but NOT
> in
> > pseudo_ibss mode, then the command does not seem
> to
> > set the card in pseudo_ibss mode.
> > 
> > I would like the nodes in pseudo_ibss mode not to
> get
> > affected by other nodes that may be misconfigured
> (and
> > hence not in pseudo_ibss mode).
> > 
> > Here are the details of the card/firmware and
> driver
> > I'm using:
> > 2511 MP PLUS: 802.11b miniPCI Card
> >
>
(http://www.netgate.com/product_info.php?cPath=26_34&products_id=29)
> > Firmware:
> > Output from hostap_diag:
> > NICID: id=0x8013 v1.0.0 (PRISM II (2.5) Mini-PCI
> (SST
> > parallel flash))
> > PRIID: id=0x0015 v1.1.1
> > STAID: id=0x001f v1.7.4 (station firmware)
> > 
> > HostapDriver version = 0.1.2
> > 
> > Please help.
> > 
> > Thanks,
> > Anand
> > 
> > 
> > 
> > 		
> > __________________________________ 
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> 
> 
> 



		
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