[CAUSE] The tmnxIsisPfxLimitOverloadWarning notification is sent when the number of prefixes in the system reaches the tmnxIsisPrefixLimitThreshold or the tmnxIsisPrefixLimit. [EFFECT] When tmnxIsisPrefixLimit is not yet reached, but the tmnxIsisPrefixLimitThreshold is reached there is no direct effect; but when the number of prefixes grows the system might go into overload. When the tmnxIsisPrefixLimit is reached and the object tmnxIsisPrefixLimitLogOnly is false, IS-IS will be in overload. There is no direct effect when the object tmnxIsisPrefixLimitLogOnly is true. [RECOVERY] Increase the IS-IS prefix limit.