[CAUSE] The tmnxSubSysNextHopUsageHi notification is sent when the IP next-hop usage by subscriber managed routes reaches its high watermark ('true') or when it reaches its low watermark again ('false'); the watermarks are derived from the limit specified with the object tmnxSubSysNextHopLimit. [EFFECT] There is no immediate effect, but when the usage actually hits the limit, new hosts will not get their managed routes [RECOVERY]