This is the maximum interval, in seconds, between generated LSPs by this Intermediate System, and it must be greater than ciiSysLevelMinLSPGenInt while sitting at least 300 seconds less than ciiSysMaxAge. This is the periodic LSP refresh interval -- the router must re-originate its own LSP before this timer expires or neighbors will age it out of their databases -- so an admin who raises this without also raising ciiSysMaxAge risks the router's own LSPs expiring in peers' databases between refreshes. For example, with the common default of 1200 seconds, the router must re-flood its LSP roughly every 20 minutes even if nothing has changed, well within a ciiSysMaxAge set to at least 1500 seconds.