A possible P2P Interoperability issue?

Jouni Malinen j at w1.fi
Tue Aug 18 10:44:44 EDT 2015

On Tue, Aug 18, 2015 at 09:18:35AM +0000, Atul Joshi wrote:
> From supplicant code I can see that, if the P2P_CONNECT command carries freq, then the same frequency is used as a part of channel list (it replaces the channel list supported by the device)
> It means if the freq is set to 5GHz, the supplicant will not include any 2.4GHz channels in the channel list in GO negotiation frames.
> This can lead to Interoperability issue. One such device seen until now nexus 5.

This is by design, i.e., the freq=<MHz> argument to P2P_CONNECT forces a
specific operating channel to be used.

> Is there a way to indicate the preferred channel but keep the channel list intact ? So that we can preferably go to 5GHz without any interoperability issue?

Ilan already pointed out to such a mechanism (there are actually number
of ways of doing this). It looks like P2P_CONNECT does not have the
pref=<MHz> parameter that is available with P2P_INVITE to indicate a
single preferred channel. I guess that could be added, but setting
p2p_pref_chan and not specifying the preference on P2P_CONNECT (or
P2P_INVITE) is quite a bit more flexible way of doing this.

Jouni Malinen                                            PGP id EFC895FA

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