I've done the UDP thing, but I assume everything has an IP address
(either DHCPor static IP). My example is done with lwip and C# code. I
can share snippets if someone is interested.
I doubt it will work with 0.0.0.0or if the devices are on different
subnets. I would suggest using the "169.254/16" class of addresses (aka
"IP4 Link Local", google for it). Windows and MacOS uses this if it
can't find DHCP.I think it would be easy to set up lwip to use it too.
Then UDP will work.
see http://tools.ietf.org/html/rfc3927
-Mark
On 3/20/2013 4:16 AM, Richner Simon wrote:
Interface with PPPoE and DHCP?
Dear Ruben,
I have thought about using broadcasts as well. The problem is, that
when I connect my laptop directly to the device, neighter one has a
valid IP (0.0.0.0). I'm not sure this would bother UDP broadcasts, but
for TCP this isn't possible for sure. So the only way I see is to use
UDP broadcasts to make sure it's a point to point connection and then
set static IPs for both sides....
Of course the question is, if you really need TCP on a point to point
connection at all.
Kind Regards
Simon
------------------------------------------------------------------------
*Von:* [email protected]
[mailto:[email protected]] *Im
Auftrag von *Ruben van der Kraan
*Gesendet:* Mittwoch, 20. März 2013 10:56
*An:* Mailing list for lwIP users
*Betreff:* Re: [lwip-users] Interface with PPPoE and DHCP?
Hi Simon,
I have a similar problem but at the moment i am not working on this
issue.
The idea I have is to send a UDP broadcast message to all the users on
the local network.
The devices that recognize the UDP frame answer tot it and now the IP
address is know to the application.
An other way is to let the device send a udp broadcast message to
every one on the network.
the C# application receives this message and then knows the IP of all
the compatible devices in the network.
You can send the broadcast every minute or so.
If you or anyone else have i better option I am interested.
Kind Regards
Ruben
On 20-3-2013 9:07, Richner Simon wrote:
Hi
I'm looking for some advice. I have a series of custom devices using
LwIP, talking to a custom C# application.
Some devices are connected to a network, using DHCP to get an IP
address. Other devices are setup for standalone use and are directly
connected to a local laptop for maintenence. In both cases I want to
use the same ethernet connetion with the same software.
I've been looking at AUTOIP, but this takes almost a full minute to
setup IP adresses, which is unacceptable. Another idea was to use one
common static IP if no DHCP server was found. The problem with this
is, that in case it's just a temporary DHCP server absence, I end up
with dozens of devices having the same IP. My last idea was to use
DHCP and PPPoE in parallel. So if there was no DHCP server, the
laptop would use PPPoE. I haven't tested this, but if my thought is
correct, this would solve both problems mentioned (to the cost of
having to implement two protocols).
If anybody has similar requirements, please let me know how you
solved this.
Am I on the right track, or is there a much simpler solution to my
problem?
Best Regards
Simon
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