Virtual Interface for P2P operations
johannes at sipsolutions.net
Fri Jul 22 13:17:22 EDT 2011
On Fri, 2011-07-22 at 09:51 -0700, Henry Ptasinski wrote:
> > Some drivers/devices would like to
> > use a separate MAC address
> To make sure we've all got the same understanding:
> The P2P spec talks about 3 types of addresses a device can have:
> WLAN address - for traditional connections
> P2P Device address - for P2P discovery and GO negotiation
> P2P Interface address - for messages sent within a P2P group
> The P2P device address can be either: the globally administered MAC
> address, or the globally administered MAC address with the locally
> administered address bit set.
Right. I'm more talking about configuration interfaces though.
> For concurrent WLAN and P2P operation, the spec requires that the WLAN
> and P2P Interface addresses be distinct.
Yeah. Right now we'll use the globally administered address for WLAN,
and another address for the P2P Interface.
> For simultaneous P2P membership in multiple groups, the spec requires
> that the P2P Interface address used in each group be different.
Yup. Different netdevs for the different P2P interfaces for this.
> The WLAN address and P2P Device address never change for a device (I think).
The WLAN address can be changed manually, but typically wouldn't. Then
the Device address would follow, currently, I think.
> > wpa_supplicant calls this the WPA_IF_P2P_GROUP but I think the term "P2P device interface" would be more appropriate here.
> Is this the P2P Device address or the P2P Interface address? "P2P
> device interface" is going to be a problematic name I think.
Well, again, I'm more thinking of configuration interfaces, not
addresses. Since it wouldn't be a netdev, it wouldn't directly have an
address, though we'd actually give it an address -- this would be the
Device address. But you're right, calling it "interface" is probably bad
idea since it's not a netdev. Maybe actually just call it "P2P Device".
> Does wpa_supplicant understand multiple simultaneous P2P groups? Is
> wpa_supplicant handling discovery and the GO negotiation, or is that
> done somewhere else?
Yes and yes.
> The WPS and the 4-way handshake happens with the P2P Interface address.
Right, and in terms of APIs it happens on the netdev. The issue at hand
is that currently in nl80211, WLAN == P2P Device, and we use the WLAN
MAC as the P2P Device MAC, and also use the WLAN netdev for the P2P APIs
for public action, discovery, etc.
> > WoP2P anyone?
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