Filter
Top Products
3-12
Cisco uBR10012 Universal Broadband Router Troubleshooting Guide
OL-1237-01
Chapter 3 Troubleshooting PRE-1 Modules
Troubleshooting Common System Problems
For information on resolving problems with high CPU usage caused by the Exec and Virtual EXEC
processes, see the document High CPU Utilization in Exec and Virtual Exec Processes, at the following
URL:
http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2ae4.shtml
Interrupts are Consuming a Large Amount of Resources
Interrupts allow software processes to request resources when needed, as opposed to waiting for time to
be allocated to the process. If a process requests too many interrupts, however, it could impact CPU
usage, resulting in less time available to other processes.
For more information, see the document Troubleshooting High CPU Utilization Due to Interrupts, at the
following URL:
http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2af0.shtml
Invalid Scheduler Allocate Configuration
The scheduler allocate command guarantees the minimum amount of time that can be allocated for
fast-switching during each network interrupt context, and the minimum amount of time that can be
allocated for non-interrupt-driven processes. An incorrect configuration for the scheduler allocate
command can cause high CPU usage, especially when too much time is allocated for non-interrupt
processes. This could result in messages such as
%IPCGRP-6-NOKEEP: Too long since a keepalive
was received from the PRE
.
We recommend using the default configuration, which can be restored by giving the default scheduler
allocate command in global configuration mode:
Router(config)# default scheduler allocate
Router(config)#
IP Input Processing
The Cisco IOS software uses a process named IP input to process IP packets that cannot be processed
using the fast-switching process. If the router is process-switching a lot of IP traffic, it could result in
excessively high CPU usage.
The most common reasons for excessive IP Input processing are that fast-switching has been disabled
on one or more interfaces, and that the router is receiving a large volume of traffic that must be
process-switched. For more information on resolving problems with the IP Input process, see the
Troubleshooting High CPU Utilization in IP Input Process document at the following URL:
http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2af3.shtml
One or More Processes is Consuming an Excessive Amount of Resources
High CPU usage could occur if one or more processes is consuming an excessive amount of resources.
For example, the router might have an excessive number of TCP connections open, or the TTY
background process is busy displaying logging or debugging messages.