All,
We as many do have the same problem and requirement. My first pass at this was to auto-assign an AutoIP address derived from the MAC address of the product. On power up every device had an IP address, and better, a known one because the device has a MAC address label. If DHCP picked up an address, it would change over. We have a ‘Discovery’ program and protocol and can list devices connected to the PC. I looked at mDNS / AutoConf but it’s a lot of development. Our protocol was expanded to get and set the IP address and MAC address so that factory boards all have the same MAC for initial testing and bring-up.
Ultimately we abandoned DHCP and ship products with a known and static IP address. We don’t want to discover on-the-fly and have access problems from the PC program and worse, we don’t want to use a device attached somewhere else in the customer’s building. This approach also forces our users to use a sub-net and get off their network. Our utility has the option to move all devices from one subnet to another in case we collide with their internal network.
In any case, starting up with a static AutoIP address worked while we used it.
Bill
From: address@hidden [mailto:address@hidden On Behalf Of Richner Simon
Sent: Wednesday, March 20, 2013 7:16 AM
To: Mailing list for lwIP users
Subject: Re: [lwip-users] 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: address@hidden [mailto:address@hidden] 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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