IPv6 on Ben Nanonote

David Kuehling dvdkhlng at gmx.de
Sun Jun 17 21:59:56 EDT 2012

>>>>> "EdorFaus" == EdorFaus  <edorfaus at xepher.net> writes:

> On 06/16/2012 02:17 AM, David Kuehling wrote:
>> Next problem: the IPv6 link-local address changes after every boot!
>> The IPv6 address is generated from the MAC-address; the MAC adress
>> changes, too.  Why???
>> Any chance we can give the Nanonotes a permanent MAC-address by
>> default?

> I remember hitting the same problem of non-static MAC addresses
> (though for IPv4 networking) a while ago, and I believe I sent some
> emails to this list about it, but apparently it never really
> took. (Hopefully you'll have better luck.)

> From what I remember, Qi doesn't have a MAC address range to assign to
> the devices, and are using the dynamic ones on purpose - but my
> suggestion was that the devices don't *need* unique MAC addresses - as
> the MAC addresses really only need to be unique on the same network,
> and each host-to-ben USB link is a separate network (on the link layer
> anyway, which is where MAC addresses are used).

WRT uniqueness of MAC addresses, I though about the same, but then came
to realize that it'd still break: the user could use a bridge device to
connect usb0 to eth0 on the ethernet level.  Then, if you have multiple
nanonotes on the resulting bridged network, MAC addresses could collide.

Unfortunately the same argument also applies to IPv6: if you configure
the same, static IPv6 link-local address for multiple NanoNotes, then in
a bridging configuration, where multiple NanoNotes are on the same link,
you'd have a IPv6 address collision :/

> This works perfectly now that I've configured my NanoNote to use a
> static MAC address (which is not overly difficult, see [1]), but I
> figured it might be a good idea to make that the default (or at least
> the (10.42.43.x) static IP that I also had to set on the NN). It seems
> like the maintainers either weren't listening or didn't agree though.

The problem is, that NanoNote is not a NIC and doesn't have a dedicated
EEPROM to save a unique MAC-address.  Once you flash two nanonotes with
the same firmware, they'd be equal down to the MAC-address, possibly
causing problems as described above.


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