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New Member

High CPU utilization due to Cat4k Mgmt LoPri in 4510R


I am facing high CPU utilzation due to Cat4k Mgmt Lopri

  52     8721440   8889916        981 94.97% 93.34% 86.96%   0 Cat4k Mgmt LoPri

The output of sh platform health;

K2CpuMan Review       30.00  69.35     30     34  100  500  119 118

The output of sh packet statistics all;

L2 Fwd Low                    18065480      3836      3579      2322        322

Please suggest how to find out the source which is making L2 Fwd Low packets.Due to which i am facing low response of applications.How to prevent this packets.I already have gone through the Cisco document.But it is not explaining how to find out the cause of these L2 Fwd Low packets.


Ikbal C


Re: High CPU utilization due to Cat4k Mgmt LoPri in 4510R

Those process (Cat4k Mgmt HiPri, Cat4k Mgmt LoPri) are normally high
because of the way the CPU is managed on 4000/4500 technologies, let me
share with you the following information about it:

This show processes cpu output shows that there are two processes that
use the CPU- Cat4k Mgmt HiPri and Cat4k Mgmt LoPri . These two processes
aggregate multiple platform-specific processes which perform the
essential management functions on the Catalyst 4500. These processes
process control plane as well as data packets that need to be
software-switched or processed.

In order to see which of the platform-specific processes use the CPU
under the context of Cat4k Mgmt HiPri and Cat4k Mgmt LoPri , issue the
show platform health command.

Each of the platform-specific processes has a target/expected
utilization of the CPU. When that process is within the target, the CPU
executes the process in the high-priority context. The show processes
cpu command output counts that utilization under Cat4k Mgmt HiPri .  If
a process exceeds the target/expected utilization, that process runs
under the low-priority context. The show processes cpu command output
counts that additional utilization under Cat4k Mgmt LoPri . This Cat4k
Mgmt LoPri is also used to run background and other low-priority
processes, such as consistency check and reading interface counters.
This mechanism allows the CPU to run high-priority processes when
necessary, and the idle CPU cycles that remain are used for the
low-priority processes. To exceed the target CPU utilization by a small
amount, or a momentary spike in utilization, is not an indication of a
problem that needs investigation. However in our case its high. It seems
that you may have hit a software bug CSCdz50987. This bug was fixed with
release 12.1(14)EW. 

New Member

Re: High CPU utilization due to Cat4k Mgmt LoPri in 4510R


Thanks for the suggestions

I already have gone through that cisco document.Accordingly captured the output of some commands(sh platform health etc)The running ios vesion is 12.2(25)SG.Not EW version.Please suggest if anything more to troubleshoot