Re: 6lowpan socket

[Alexander Aring <alex.aring@gmail.com>]

On Fri, Nov 13, 2015 at 11:29:36AM +0100, Baptiste Clenet wrote:
> 2015-11-12 9:53 GMT+01:00 Alexander Aring <alex.aring@gmail.com>:
> > Hi Baptiste,
> >
> > On Thu, Nov 12, 2015 at 01:14:48AM +0100, Baptiste Clenet wrote:
> >> From Christopher:
> >>
> >> Oh - sorry. 6LowPAN uses IPv6. So it's equivalent to setting up an IPv6 socket.
> >>
> >> Just remember to set up routes as appropriate and it should work fine.
> >>
> >> Unfortunately, I think vger bounces email from android devices, so my
> >> message won't make it out on the list.
> >>
> >> ©
> >>
> >> Sent from my Android
> >>
> >> Yeah sure, it's equivalent, it's what I thought. I will search deeper
> >
> > I see you as well on the RIOT mailinglist. Do you has these issues with
> > RIOT?
> >
> 
> Yes I'm in both mailing list.
> The problem was not with Riot but openwrt. It works now, thanks you.
> 

ok.

> > You can check it with fakelb and bsd-netcat and create/connect udp v6 socket,
> > if it works with a linux<->linux connection, otherwise something is
> > wrong with interoperability (which you can might debug via sniffing).
> >
> > I know they have recently added the rfc6282 udp nhc compression, see
> > [0]. We have nhc_udp enabled by default, (receive handling should have
> > a always possible strategy).
> >
> > Usually you can disable UDP NHC by unloading the "nhc_udp" module if you
> > built it as module. But then you can also not receive anymore other udp
> > nhc iphc headers.
> >
> > To make a fine granularity setting to the nhc strategy, we need a
> > userspace tool and interface for that.
> >
> > - Alex
> >
> > [0] https://github.com/RIOT-OS/RIOT/pull/4189
> 
> 
> Ok for nhc compression, I let the default configuration and it worked.
> 

You should look for "default configuration" a look into rfc6282. There
is a special port-range which can be compressed. Maybe you want to use
that. It will be used automatically.

> I'm wondering something else about IPV6, how to change the default
> IPV6 that the at86rf2XX will trigger?
> If we change the IPV6 of lowpan0 (with ip -6 addr del ... for
> instance) and then add the new one, it doesn't affect the reg
> IEEE_ADDR_0,1,2....

mac address != ip address.

with ip -6 addr you mean == ip address.

with ip link set dev xx address yyy == mac address.

> So I wanted to use iwpan but I can only change the short_addr if I'm not wrong.

short address is part of mac address which is currently not supported by
802.15.4 6lowpan. This is a bigger issue because the whole ipv6
stack/net core api does know only _ONE_ type of mac address and this has
only _ONE_ length.

There exists few ideas to handle that, but we need to talk about which
is the right one...

> Which way is the cleanest to edit the IPV6 address of the transceiver?
> (and it will impact lowpan0) I thought about edit it in the at86rf23XX
> driver.
> 

There is a bug one some kernel versions, see [0]. If you want a new mac
address, ifdown both wpan/lowpan interface -> then change mac address
via ip link set ... (extended address). Then ifup both interfaces again.

- Alex

[0] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/net/mac802154/iface.c?id=09095fdc9e5d5438051fc4e92867f1aff764cd21