15.10.1 Discovery and data synchronization

As network administrators add, delete, and modify devices on a network, the regional servers, such as regional1 and regional2, discover those changes and update the global server, such as global1 in the example in this chapter. regional1 and regional2 also notify global1 of changes that administrators make to the management modes of the nodes they manage.

Note: To maintain consistency, as regional1 and regional2 discover device state changes, they continuously update global1, thereby maintaining identical node states on both the global and regional servers.

Any time global1 requests information about a node that is managed by regional1 or regional2, regional1 or regional2 responds to global1 with the requested information. global1 never talks directly to a node. There will not be duplicate SNMP queries to devices when global1 performs a discovery.

global1 synchronizes with regional1 and regional2 each time regional1 or regional2 completes a discovery. NNMi uses forwarding database (FDB) data to calculate Layer 2 connections. FDB data is very dynamic, and varies a lot between discoveries, especially if there are multiple regionals connected to a global server.

Note: Changes to user-modified or application-modified attributes are not updated on the global server during a synchronization.

The Rediscovery Interval is adjustable on each regional server, which means there might be differences in the discovery accuracy between global1 and the regional managers. The shorter the Rediscovery Interval, the more accurate the discovery will be and the more NNMi-generated traffic there will be on the network. The longer the Rediscovery Interval, the less accurate the discovery will be and the less NNMi-generated traffic there will be on the network. This means that as your network grows larger, you might want to perform rediscovery less frequently. To set the Rediscovery Interval, do the following:

From the regional1 or regional2 NNMi console, click Discovery > Discovery Configuration in the Configuration workspace.
Adjust the Rediscovery Interval to reflect how often you want the regional server to initiate discovery.

The global server will initiate discovery immediately after a regional server completes a discovery.
Click Save and Close.

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