Question

I am developing an embedded system and very new to this TCP\IP. My problem is that once I installed my board in a local network and this board will acquire its IP address dynamically, it has to communicate with a client application running on one of the PC(other than DHCP server) in the network. To communicate with this new board the client application is required to know the IP address of the board. What is the way to know the IP address of the board? Will UDP broadcast work for this purpose? If yes please, explain in detail as I am unable to understand it. Please provide me some sample code in C if possible.

Answer 1

The basic idea is:

• Embedded system software opens a UDP socket, binds it to a well-known port and sets the SO_BROADCAST socket option with setsockopt(). It then calls recvfrom() to wait for packets in a loop.
• Define a packet format that allows a packet type to be specified. Define a “discovery” packet type.
• If the embedded system recieves a “discovery” packet, it responds to the sender with a packet that might contain its name/serial number/uptime/status.
• Client software opens a UDP socket, sets the SO_BROADCAST socket option and sends a “discovery” type packet to the well-known port and the local broadcast address.
• Client software waits for response(s) from each embedded system with recvfrom(), recording the address of each.
• Client picks an embedded device and starts communicating directly with it.