If you've used Discovery at all, you're familiar with the Discovery Status form — but you may not realize that there's another, deeper layer of information available to you. This layer gives you the history of exactly what happened to a particular device within a particular discovery — very handy for troubleshooting, and also for learning about how Discovery actually works.
During the discovery of a range of IP addresses with many devices, Discovery is doing lots of things simultaneously with lots of different devices. Looking at that entire picture is confusing and sometimes can be a bit overwhelming. But if you know how to use the Discovery Device layer, you can look at the events concerning an individual device in isolation.
Let's start by looking at the Discovery Status form for a discovery that ran this morning here at the Wooden Spaceship (screenshot at right). Toward the bottom of this form you can see some of the devices that were discovered. We're going to look into what happened witht he printer named snc-minolta1, by clicking on its IP address in the Discovery Devices list (I've highlighted this in orange).
Once we do that, we'll see the Discovery Device form. On this form, the Discovery Device History Log lists the high level events that happened on this discovery, on this printer: Ping found an active address, PortScanner found ports 161 (SNMP) and 80 (HTTP) open, SNMP recorded basic information and printer information. You can get even more detail from here, too — just click on the Show ECC Queue Entries link (I've highlighted this in orange).
Now you're looking at the nitty-gritty details (screenshot at right) of what Discovery did to explore this printer: every probe launched (those rows where Queue is "output"), and every response the MID server sent back (those rows where Queue is "input"). Drilling into any of the probe response records will show you exactly what information the probe returned — very useful for troubleshooting. For instance, if discovery found the wrong model number for this printer, we could drill into the SNMP Classify/Identify probe response record to see exactly what model number information discovery got from the printer.
Get familiar with these tools and the information they provide — they'll save you a lot of time if you know how to use them!
