Saturday, October 1, 2011

NPC Sites and Groups 4 of 7: NetVoyant Discovery Scopes


I have a philosophy about NetVoyant and discovery scopes. I believe that NetVoyant should be opened up to all segments of the network. Most people disagree saying there’s no need to discover workstations and printers.

While I agree that there’s not much value in discovering or polling people’s desktops or laptops nor network attached printers, there are mechanisms built into NetVoyant that allow partial discovery of those devices without using licenses. In fact, NetVoyant is setup by default to ignore workstations and printers. During discovery, NetVoyant will attempt to get the sysObject OID. Based on this sysObject OID, NetVoyant knows what type of device is being discovered. If it is a workstation or printer, it will be classified as such and placed into the workstations or printers group and discovery will halt for those devices.

The best scenario will depend on each individual situation. I’ll detail a middle-of-the-road solution that should work in indecisive situations.



NetVoyant essentially only needs two pieces of information to start monitoring IT resources: discovery scopes and SNMP community strings. The configuration of SNMP community strings is done in NPC and is luckily synchronized throughout all the products. Configuring NPC to have all the possible community strings will eliminate this step from the NetVoyant setup.

Discovery scopes determine what devices to monitor. NetVoyant attempts discovery of all the IP addresses in the scopes by first pinging the IP address via ICMP. If the ping is successful, a device record is added to the NetVoyant database. Then NetVoyant tries all the community strings configured in NPC to try to get the sysObject OID of the device. If successful (and the device model is enabled for discovery), NetVoyant continues discovery by looking for any poll instances for the configured datasets.

Using the Sites/Network list, scopes encompassing all sites can easily be built.

Figure 9: Discovery Scopes from Sites/Networks List
Until metadata can be added to the scopes, only the network number and mask are needed. These scopes can be added manually when the setup wizard runs or can be added later via the Config tab. Of course, expert attention should be paid to the Device Models and Device Classes configurations as well as the Model field on each dataset, discovery rules, and auto-enable rules. Since those few topics could fill volumes, I’ll leave that to later best practice documents.

The discovery scopes could be added manually, but could alternatively be imported via CSV. The CSV file syntax is simple, only requiring the network number and subnet mask separated by a comma. Valid examples of CSV entries are listed in the AdminGuide and are shown below:

192.168.123.1
192.168.123.2,255.255.255.255
192.168.123.3/32
192.168.123.0/24
192.168.124.0,255.255.255.0

To be continued...