Hello Alexander,

Glad to hear that folks are trying to implement RFC 7668.

You are right in conclusion that no u or g bit handling is required.

>From RFC 7668, section 3.2.2 -- it says that one should use 48-bit BT
device identification  and form the 64-bit IID  separated by oxFFFE. The BT
identification bits are marked as 'b' in the specification and they stay
unchanged. So U/L considerations are not needed.

This is still following RFC 7136 method of IPv6 address formation as the
48-bit BT device identification is not the same IEEE based 48bit MAC
address.

Thanks,
-Samita



On Sat, Feb 25, 2017 at 10:25 PM, Alexander Aring <[email protected]>
wrote:

>
> Hi,
>
> On 02/26/2017 07:05 AM, Alexander Aring wrote:
> >
> > Hi,
> >
> > On 02/24/2017 01:14 PM, Luiz Augusto von Dentz wrote:
> >> From: Luiz Augusto von Dentz <[email protected]>
> >>
> >> Accourding to RFC 7668 U/L bit shall not be used:
> >>
> >> https://wiki.tools.ietf.org/html/rfc7668#section-3.2.2 [Page 10]:
> >>
> >>    In the figure, letter 'b' represents a bit from the
> >>    Bluetooth device address, copied as is without any changes on any
> >>    bit.  This means that no bit in the IID indicates whether the
> >>    underlying Bluetooth device address is public or random.
> >>
> >>    |0              1|1              3|3              4|4              6|
> >>    |0              5|6              1|2              7|8              3|
> >>    +----------------+----------------+----------------+--------
> --------+
> >>    |bbbbbbbbbbbbbbbb|bbbbbbbb11111111|11111110bbbbbbbb|
> bbbbbbbbbbbbbbbb|
> >>    +----------------+----------------+----------------+--------
> --------+
> >>
> >> Because of this the code cannot figure out the address type from the IP
> >> address anymore thus it makes no sense to use peer_lookup_ba as it needs
> >> the peer address type.
> >>
> >
> > I am still not quite 100% of this and want to leave my opinion about this
> > handling which can be interpreted in a different way.
> >
> > The RFC says here:
> >
> > Following the guidance of [RFC7136], a 64-bit
> > Interface Identifier (IID) is formed from the 48-bit Bluetooth device
> > address by inserting two octets, with hexadecimal values of 0xFF and
> > 0xFE in the middle of the 48-bit Bluetooth device address as shown in
> > Figure 6.
>
> Okay, they said from IID from the 48-bit address.
>
> And IID is what you need here and what [RFC7136] describes as result,
> so I think you are right.
>
> There is no need for special u/l bitflip or link-layer multicast handling.
>
> - Alex
>
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