Re: 6lowpan on a RPi using at86rf233

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

On Tue, Apr 07, 2015 at 01:49:21PM +0200, Guido Günther wrote:
> On Fri, Apr 03, 2015 at 08:38:06PM +0200, Alexander Aring wrote:
> > On Fri, Apr 03, 2015 at 08:27:44PM +0200, Guido Günther wrote:
> > > On Fri, Apr 03, 2015 at 04:45:02PM +0200, Alexander Aring wrote:
> > > > On Fri, Apr 03, 2015 at 04:36:47PM +0200, Guido Günther wrote:
> > > > > Hi,
> > > > > I'm trying to get 6lowpan to work using bluetooth-next on the above
> > > > > hardware[1]. I'm currently using bluetooth-next as of
> > > > > baf880a96859cca79208122e555e7efeabd16e4d . When I do a:
> > > > > 
> > > > >    iwpan dev wpan0 set pan_id 0xbeef
> > > > > 
> > > > > I get:
> > > > > 
> > > > >    command failed: Device or resource busy (-16)
> > > > > 
> > > > 
> > > > you can set the pan_id when you interface is down only.
> > > 
> > > There was an ifplugd on the pi which continued to up the device -
> > > damnit. Sorry for the noise. I can now ping the two devices but am
> > > seeing massive packet loss:
> > 
> > This "ifplugd" thing is a common issue, most people which using raspbian
> > reported similar issues.
> 
> I've documented this at [1] so hopefully Google helps to avoid this a bit.
> 

thanks.

> > 
> > > 
> > >     # ping6 -s 20   -I lowpan0  fe80::f836:9287:905c:a684 
> > >     PING fe80::f836:9287:905c:a684(fe80::f836:9287:905c:a684) from fe80::cb23:b779:742d:4fd2 lowpan0: 20 data bytes
> > >     28 bytes from fe80::f836:9287:905c:a684: icmp_seq=3 ttl=64 time=27.7 ms
> > >     28 bytes from fe80::f836:9287:905c:a684: icmp_seq=4 ttl=64 time=12.7 ms
> > >     28 bytes from fe80::f836:9287:905c:a684: icmp_seq=5 ttl=64 time=12.7 ms
> > >     ^C
> > >     --- fe80::f836:9287:905c:a684 ping statistics ---
> > >     16 packets transmitted, 3 received, 81% packet loss, time 15017ms
> > > 
> > > Will need to dig into this again.
> > >
> > 
> > mhh, is this a linux to linux connection? Maybe try to activate ARET
> > mode, you can do that with:
> 
> Linux to Linux, yes. Thought that this is simpler before trying to talk
> to Contiki.
> 

yep.
> > 
> > iwpan dev wpan0 set max_frame_retries 3
> > 
> > or something differs with 3, -1 will turn off the ARET mode. Value 0
> > will do csma handling only. All above 0 will do retransmission tries.
> > You should do that on both nodes and all nodes in your network need to
> > support AACK handling. (Automatck ACK).
> > 
> > Or maybe switch channel, I am running out of ideas now. :-)
> 
> I turned out that the 1.5 meters with some metal in the walls was far
> too much of a faraday cage for that module (altough it isn't a problem
> for 802.11). Moving things closer together made the packet loss mostly
> go away.
> 

are you sure? The 12.7 ms for 28 bytes with a link-local (I suppose
SLAAC) smells like a small spi clock and I don't believe that. Can you
try a "ping -s 500 ..." then you can test fragmenation handling, I had
big issues with fragmentation (means it doesn't worked) and a slow spi
clock ~500Khz. Try my dts at86rf233 entry for the RPi in my other mail.

- Alex