These messages are caused by RMON alerts and events configuration. Check your config from "rmon alert ..." and "rmon event ..." commands. If they are not showing up in the config, they could have been configured using SNMP, and not placed into the running config. In that case, a reload of the device would remove them.
RMON (remote monitoring) is a branch of the SNMP MIB tree which provides for nine groups of statistical and historical monitoring. Two of the groups, events and alarms, also allow you to generate notifications when a threshold is violated. The first message indicates that whatever is being monitored by etherStatsIndex 4 has exceeded its configured etherStatsPkts128to255Octets threshold of 1750000000 packets. This means that for the configured monitor interval, this interface processed more 1,750,000,000 packets that were between 128 and 255 bytes long.
The second message indicates that the packet count has dropped below the falling threshold of 1000000000. At this point, the rising threshold re-arms.
These packet rate values are configurable when you define the RMON alarm.
