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RE: [bluetooth-dev] Point-to-MultiPoint with Ericsson HW



Hi,

If you intend to make sure the other side supports a roleswitch before
it actually is done you can issue the remote_supported_features cmd as you describe. This SHOULD
work anytime after a successful paging procedure and I really have no idea why
it doesn't work for you. Which HW do you use? 

You can always try to do the role_change after you got a 
baseband connection and if it fails decide if you want to keep
the connection or not. Another way is that you ask to be
master when you accept the connection, and the role_change event
will tell you if it succeed or not. The problem with this is 
that some vendors (CSR and maybe others) 
will actually bring up the link even if the role change failed. This 
means that the other side probably will continue to setup l2cap and 
you have to deny the connection at that level and then bring down 
the baseband connection yourself. My opinion is that if you use the
accept_connection cmd with the masterflag set, the baseband really
should terminate the connection if a rolechange fails. If you want
to decide this later you can just accept the connection and then
issue the role_change cmd. There are reasons why CSR do like this
and mainly because there are some clashes between the corespecifications
and the GAP-profile so it's difficult to say how this really should work. 

I see no reason why you want to know if the remote device
support it or not before you do the switch. As the supported_features
cmd only can be issued when you already have a connection I think
it's waste of time to ask for it, just do the roleswitch and check
the resulting event to decide how to proceed. So if you intend to 
act as master in a piconet you should always be master and don't 
allow any devices which can't do the M/S switch otherwise you will 
end up with a scatternet which will prevent any other connections 
(if the module doesn't support scatternet, I'm not sure which vendors that actually
support it).

Best Regards
Anders Johansson

> -----Original Message-----
> From: Ilguiz Latypov [mailto:ilatypov@xxxxxxx.com]
> Sent: Thursday, December 06, 2001 8:11 AM
> To: OpenBT Development List
> Subject: RE: [bluetooth-dev] Point-to-MultiPoint with Ericsson HW
> 
> 
> 
> Hello,
> 
> I have a question on a temporary scatternet mode mentioned in the list
> recently.
> 
> I wonder if it is possible for the multi-point-capable server 
> side chip to
> discover the remote chip's features before switching the role.
> 
> I believe the originator of the connection is a master unless the
> recepient supplies the 0x00 value to the Role parameter of the Accept
> Connection Request command (see p.574 of Bluetooth Spec 1.1).
> 
> There is also the Switch Role command.
> 
> Some devices don't support role switch.  Their capabilities 
> can be found
> through Read Remote Supported Features and Read Local 
> Supported Features
> commands.
> 
> I understand that the role switch is necessary to serve multiple
> connections.
> 
> I was trying to investigate if a multipoint server side device can
> discover the capabilities of the client without switching the roles.
> However, my test failed with the error code 0x0E (host rejected due to
> security reasons).
> 
> The connection negotiation has completed before I sent the 
> remote features
> inquiry.  Authentication commands with regard to PIN codes 
> and link keys
> have been served.  I wonder what could prevent me from 
> getting the remote
> features at that time.
> 
> Ilguiz
> 
> On Wed, 5 Dec 2001, Peter Kjellerstedt wrote:
> 
> > > CONFIG_BLUETOOTH_EARLY_MSSWITCH
> >
> > Does the switch immediately. Otherewise a scatter net is
> > created temporarily. This is required for CSR modules, but
> > I think the Ericsson module can do without it.
> 
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