Hardware discovery take place in two steps
In the first place, the IP search module detects the hardware on the network, even equipped with a firewall. Once an agent has received the order to proceed the IP scan, it identifies the first network interface to use. He try to resolve all other IP address in the subnet using the ARP protocol. All the IP scan data are sent to the server (XML format).
In a second time, SNMP scan (function added in OCS Inventory NG 2.0) will improve data received by IP discover. Using SNMP scan, you’ll be able to get informations from network devices : scanner, computer without agent, router, etc.