[riot-devel] Border-router and multicast

Baptiste Clenet bapclenet at gmail.com
Mon May 9 18:20:48 CEST 2016


2016-05-09 16:44 GMT+02:00 Alexander Aring <alex.aring at gmail.com>:
> On Mon, May 09, 2016 at 04:24:34PM +0200, Baptiste Clenet wrote:
>> Hi Martine,
>> Thank you for the answer.
>> Ok ff04::1 is also a multicast address so I add it to every board with
>> gnrc_networking and I should be able to ping them with this multicast
>> address.
>> Shouldn't I use:
>> ifconfig 7 add multicast ff04::1
>> ?
>>
>> I'm missing something here, could give me an explanation please:
>> Before, I had a transceiver plugged on my linux so I was able to ping
>> my board directly using fe80::address so I was able to use the local
>> multicast address ff02::1, now that I use border router, I'm using a
>> prefix 2001::db8 (why? and why documentation prefix?) Why can't I use
>> fe80 as before?
>
> because link-local ff80::/10 will not be routed, between lowpan and
> ethernet interface, so far I know.

ff80? You meant fe80? I was able to do ping with fe80 and lowpan0.
>
> I think what you want to have is the npd proxy magic stuff. See [0].
> Just plugin the ethernet cable and your network will be extended with
> the 6LoWPAN nodes.

What I want is to understand a bit better how my network works.
Each node is inside the same PAN (let's say 0x23 by default on RIOT,
any reason why you choose 0x23?)
RIOT starts and we affect an link-local address fe80 so every RIOT
node can ping another one with its link-local address.
Then comes border-router, border router will tell every node to add a
new ip with prefix 2001:db8::, is this right?
How often does border router send a message to other node to say to
add this new ip address?
Why 2001:db8 has been chosen? and how should I choose this prefix if I
want to use my product for commercial use?

Why can't I ping a link-local address from Linux with the border router?
I've got ten nodes and one linux with a border router, what I want is
to be able to send messages to each of them (or all of them by
multicast) at any moment, here I don't understand why I should use
global address 2001:db8 instead of fe80::

Thanks for your time,

>
> I need to admit, I tested the manual stuff "ip -6 neigh add proxy ..."
> only and never the ndppd (btw, there exists some offers to move this
> handling into kernelspace to make it more easier for users).
>
> If you want to test it, please share your expierence.
>
> - Alex
>
> [0] https://github.com/DanielAdolfsson/ndppd
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-- 
Baptiste


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