Vendor implementation of device serial numbers can be somewhat unpredictable.
When devices manufactured by Cisco Systems are discovered during the Network Inventory, Vivinet Assessor queries their entity MIBs to collect information about device serial numbers. In our testing, we have found some discrepancies between what is retrieved from the entity MIB and the actual serial number imprinted on the device itself.
In addition, we have seen discrepancies between what the Cisco IOS command show diag returns for router serial numbers and what Vivinet Assessor gets when it queries the router MIB. For example, you might use the show diag command to get a device serial number and find that the number returned is different from the one that was recorded in the assessment database during the Network Inventory. Or Vivinet Assessor might return multiple serial numbers for a device, including some that are not returned by show diag.