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New Member

High CPU due to HLFM address learning process

Hi Pro,

I am facing a strange issue in our metro-E setup. All the switches (3560 and 3750) are running MSTP in single region and all the switches had high CPU due to "HLFM address learning process". Because of high CPU all metro interconnect links flapped due to UDLD Err Disable. I could not find any concrete explanation of what "HLFM process" mean? In, it says as IP Local Forwarding Manager but not much detail.

Jan 20 04:03:24.526 IST: %SYS-3-CPUHOG: Task is running for (79439)msecs, more than (2000)msecs (3769/11),process = HLFM address learning process.

-Traceback= 2BF605C 18E2CC0 18E3498 1926048 159126C 159190C 1B1A4A8 1B10F78

I would like to know the root causes for "HLFM address learning". Could this be something because of MAC flooding or temporary loop in the metro cloud.

Thanks in advance


New Member

High CPU due to HLFM address learning process



%SYS-3-CPUHOG: Task ran for [dec] msec ([dec]/[dec]), process = [chars], PC
= [hex].
Explanation: Every process that runs must relinquish the processor after a certain
period so that other processes can run. 'CPUHOG' is an informational message that
occurs when a certain process holds the CPU for 2000 msec or longer. This problem
can occur due to one or more of these conditions:
  Heavy Traffic
  System load
  Faulty hardware
  Improper operational configuration
  Configuration change
  Initialization of many interfaces
  High momentary error rate
  Sustained abnormal condition
  Software bug in the IOS during normal operation.
Recommended Action: If communication is fine, and no other messages are displayed
before this message, you can ignore the CPUHOG message. If another error message
appears along with this message, decode the other error message using the Error
Message Decoder tool
. If the CPU usage is high because of IP input process, then
the router is process-switching a lot of IP traffic. Enable CEF to lower the CPU
usage by this process. Review the Bug Toolkit for potential issues related to
this issue.