Methods of detecting and assigning IP addresses to devices with ARP requests
A method of discovering and assigning an IP address to a device to be discovered in a communication network having multiple interconnected nodes includes continuously monitoring, by the device to be discovered, the network for address resolution protocol (ARP) requests. The discoverer node transmits a number of ARP request to the network. The device to be discovered receives the number of ARP requests. The device to be discovered determines whether the number of ARP requests are unanswered by other devices in the network. The device to be discovered answers to the number of ARP requests with an ARP reply to claim an IP address associated with the number of ARP requests. The discoverer node and the device to be discovered exchange a pair of User Datagram Protocol (UDP) packets to complete the detection process.
1. A method of assigning an IP address in a network, the method being implemented by a discoverer node, the method comprising:
selecting an IP address, at the time of selection the IP address being unused in the network;
transmitting a plurality of address resolution protocol (ARP) requests associated with the IP address;
receiving an ARP message associated with the IP address, the ARP message having been transmitted by a detected device responsive to the detected device receiving all of the plurality of ARP requests;
transmitting a user datagram protocol (UDP) packet addressed to the detected device; and
receiving a UDP reply, the UDP reply having been transmitted by the detected device, the IP address then being assigned to the detected device.
2. The method of claim 1 wherein the plurality of ARP requests is a predetermined number.
3. The method of claim 1 further comprising using a timeout counter and discarding ARP messages received after the timeout counter expires.
4. The method of claim 3 further comprising waiting a random period of time after the timeout counter expires and then restarting the method.
5. The method of claim 1 further comprising receiving a second ARP message and verifying that it is not from a second detected device.
6. The method of claim 1 wherein the UDP packet is addressed to a uniquely assigned port number.
7. The method of claim 1 wherein the UDP packet contains settings for the detected device.
8. The method of claim 1 further comprising saving the address of the detected device after receiving the ARP message or the UDP reply.
9. A method of assigning an IP address in a network, the method being implemented by a detected node, the method comprising:
monitoring the network for a first address resolution protocol (ARP) request;
receiving a predetermined number of ARP requests, the ARP requests being transmitted by a discoverer node in the network, the ARP requests associated with an IP address, the IP address being unused in the network;
claiming the IP address and transmitting an ARP reply associated with the IP address responsive to receiving all of the predetermined number of ARP requests;
receiving a user datagram protocol (UDP) packet, the UDP packet addressed to the IP address; and
transmitting a UDP reply to the discoverer node, the IP address then being assigned to the detected node.
10. The method of claim 9 further comprising counting the number of ARP requests received and waiting a predetermined time after receiving one of the ARP requests, and resetting the counter if a subsequent ARP request is not received within the predetermined time.
11. The method of claim 9 wherein after transmitting the ARP reply waiting a second predetermined time, and ignoring the UDP packet request if it is received within the second predetermined time.
12. The method of claim 9 further comprising extracting detected node settings from the UDP packet.
13. The method of claim 9 wherein the UDP packet is addressed to a uniquely assigned port number.
14. The method of claim 9 wherein the UDP reply contains information about the detected node.