Re: 6lowpan on a RPi using at86rf233

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

Hi,

On Thu, Apr 09, 2015 at 11:06:52AM +0200, Guido Günther wrote:
> 
> SSHing between the machines is ok. Nice.

For tune-up tcp connection I set also set tcp window size;

#reduce tcp receive buf, will improve tcp connections
echo "127 512 1024" > /proc/sys/net/ipv4/tcp_rmem
echo "127 512 1024" > /proc/sys/net/ipv4/tcp_wmem

This will do this for all tcp connection. You can also try to set MSS
with ip6tables.

to have much fragments isn't good on a 6LoWPAN connection. Upper layers
like CoAP, etc. will handle this. Also a general TCP connection isn't
good, because the ACK handling stuff. Maybe want to try out "mosh with
ipv6 support [1]" - currently only available on dev branch.


High fragments and fq_codel qdisc will also occur trouble, because the
skb's are too long inside the queue and fq_codel will drop them then.
This occurs on my setup at payload of ~2000 bytes, but we should never
reach such payload, also 1024 is too high. If you use with contiki I
don't think that contiki implement ipv6 fragmentation, so you can set
the highest payload to 1280. Does somebody knows if contiki supports
ipv6 fragmentation?

- Alex

[1] https://github.com/keithw/mosh