Peer to peer Ethernet shield

Hi,

I did investigate the ethernet shild library. I understand that there MUST be a server. If a server send a message to one cleint, then ALL the client receive that message. that in my case will create a lot of traffic for nothing.

Is there a way that : A server send a message ONLY to one specified client (using his IP or MAc adress) ? in this case, I can send all messsage to a server and adress one by one the clients

OR

Is there a way that a shield send a message only to one of the other 80 shield connected, assuming i need also all message of 80 clients somewhere.

Thanks

Seb

freeseb: Hi,

I did investigate the ethernet shild library. I understand that there MUST be a server. If a server send a message to one cleint, then ALL the client receive that message. that in my case will create a lot of traffic for nothing.

If we don't have a server, who is listening?

Cheers, Kari

On a TCP/IP with computer, all connected devices can talk each other. even if there is no server. I expected the same with the ethernet shield.

Anyway, I can live with a server need. My issue is i want to avoid that any message sent from the server will adress to ALL connected clients

Seb

I thought that is sort of an server function inside whatever device you are using. The part of the code that is listening, is server? Right?

Or is there other way to get to know that somebody's trying to get your attention?

Cheers, Kari

in fact it is 1-1 x 40

1 arduino named 1A that has sensors connected 1 arduino named 1B that is used to display info send by main arduino and which is 10m distance from 1A

this is x40 : 2A/2B, 3A/3B

of of course, i need a contral point where I get all data sent by xA arduinos

Seb

You may need to run both client and server code on each arduino. Somebody may have done this with an aquarium setup on the old forum. The server code would need to be running in the main loop waiting for incomming request, and the client code would be in the main loop, activated when some event is detected.

Is there a way that : A server send a message ONLY to one specified client (using his IP or MAc adress) ? in this case, I can send all messsage to a server and adress one by one the clients

This is the difference between a switch and a simple hub. Assuming you are talking about the wired ethernet shield.

You are conflating/confounding/confusing various issues.

If you want to send a packet to only one system then that is all you do. The switch contains the logic to connect the correct wire pairs directly. You do not normally "multi-cast" when doing data collection systems. It makes no sense. So you connect via the IP address... and possibly the port number.

If you are talking about WiFi -- the broadcast system is another issue.

What I think you mean is a data collection system using Ethernet -- and I do exactly that using UDP packets. I simply use the send mehtod and pscify the IP address and the Port on the SERVER -- which receives the data in UDP systems. The Client collects and sends.

freeseb: in fact it is 1-1 x 40

1 arduino named 1A that has sensors connected 1 arduino named 1B that is used to display info send by main arduino and which is 10m distance from 1A

this is x40 : 2A/2B, 3A/3B

of of course, i need a contral point where I get all data sent by xA arduinos

Seb

This_doens't_compute...???

Kari

On a TCP/IP with computer, all connected devices can talk each other. even if there is no server. I expected the same with the ethernet shield.

I think that is somewhat simplistic thinking.