High CPU due to HLFM address learning process

netops044 · ‎01-20-2012

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 cisco.com, 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

Arun

roberto.gagliardi · ‎01-20-2012

Hi

ERROR MESSAGE NOTIFICATIONS (if any)

%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.