How does network discovery deal with multiple Network interfaces

The TS.Census or ZAM client binds itself to a single IP address, and it leaves it to Windows to choose which one. It will then respond to requests made to that IP for the device's MAC address, chassis serial number, workstation ID, client version, and install type.

This is not a trivial thing to resolve. Perhaps if the device had an SNMP client installed, from which we request the list of interfaces on the device, we might have a way to figure out that the two IP addresses were on the same device. Without an SNMP client, which is most often the case for Win32 devices, we might be able to get some clues from WMI, if the device had a WMI client installed, or perhaps the TS.Census client could be changed so as to listen to all IP addresses on the device. But at this point in time network discovery will simply list each interface as a separate device'.

The below paragraph explains how the Network Discovery Engine goes about determining a device's MAC address, how the TS.Census or ZAM client fits into the picture, and a section that describes how the Network Discovery Loader reconciles one scan with a subsequent one.

Network Discovery does an ICMP ping on every IP address in the specified scan range. Each IP address that fails to respond to the ping is discarded from further consideration. Each IP that responds to the ping is interrogated for an SNMP client. If an SNMP client is installed we get the MAC address associated with the IP address from a table in MIB-II. If no SNMP client was found, or it did not return the MAC address, the IP address is put on a queue to wait until the rest of the range of IP addresses have been scanned.

Whenever Network Discovery finds a router with an SNMP client, it requests and saves off its router table, which among other things, contains the IPaddresses and associated MAC addresses of recent traffic through the router. At the conclusion of Network Discovery, one last pass is made through the queue of IP addresses with unknown MAC addresses, attempting to find the IP addresses in any router tables encountered during the scan.

The TS.Census Client or ZAM client binds itself to a single IP address on a Win32 device. If there are more than one, it leaves it up to Windows to choose which one. For each active IP address found by Network Discovery, it will attempt to communicate with a TS.Census client bound to it, if any. Upon success, the client will return the device's MAC Address, Chassis Serial Number, Workstation ID, Client Version, and Install Type.

The Network Discovery Loader attempts to reconcile the current scan results to previous results. It does this by comparing the values in certain key fields, assigning varying numbers of points to matches. High points are given for MAC address and chassis serial number matches. Medium points are given for matches on DNS Name, asset tag, and SNMP system name and system location. Minimal points are given for matches on manufacturer, product name, IP address, and SNMP system service, system contact, and system description fields. Whatever device from the previous inventory yields the highest score when compared to the current results is considered a match, above a minimal score threshold.