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The "%CPU_MONITOR-6-NOT_HEARD" and "%CPU_MONITOR-3-TIMED_OUT:" error messages are displayed in the logs of a Cisco Catalyst 6500 series switch

Core issue

The %CPU_MONITOR-6-NOT_HEARD: CPU monitor messages have not been heard for [dec] seconds is displayed when heart beat Inter Process communication (IPC) messages do not exchange between the Route Processor (RP) or MSFC and Switch Processor (SP) or Supervisor Engine for a significant amount of time.

These messages can also be exchanged between the Supervisor Engine and line cards. The [dec] indicates the number of seconds. A timeout is likely to occur and reset the system.

The %CPU_MONITOR-SP-3-TIMED_OUT: error message means that the CPU monitor messages failed and the system is no longer operational.

The problem possibly occurs because of these reasons:

  • Badly seated Module
  • Bad ASIC or bad backplane
  • Software bugs
  • Mis-seated or improperly seated line cards
  • Parity error
  • High traffic in the Ethernet out of band channel (EOBC) channel

The EOBC channel is a half duplex channel that services many other functions, which includes Simple Network Management Protocol (SNMP) traffic and packets that are destined to the switch. If the EOBC channel is full of messages because of a storm of SNMP traffic, then the channel is subjected to collisions. When this happens, EOBC is possibly not able to carry IPC messages. This makes the switch display the error message.


As a workaround, try to re-seat the module or line card.

If the problem persists, contact Cisco Technical Support with the crash info messages stored in the Supevisor bootflash or MSFC bootflash.