CPU Utilisation high on Cisco 2900 series Router

[sreeraj.murali]

Hi,

I am having the Cisco 2900 series Router, continuosly peaking the CPU utilisation. The Router running GRE Site to Site tunnel(not passing traffic at the moment, as its a backup connectivity) and is passing the office Internet traffic. The Router is continuosly peaking the CPU utilisation. I am attaching the show tech. Please check and comment.

Thanks & Regards

Sreeraj

[Mark Malone]

You should capture the cpu as its spiking so you can see exactly what process is causing the issue

Your show tech came back clean , no issues in the cli analyzer , cpu is low at the time it was taken

all it gave back was informational no critical issues

Restrict SNMP community access with ACL as a security best practice

SNMP is enabled but not running version 3, which is a security best practice

Service password encryption disabled causing cleartext passwords to be saved in the configuration

IOS Context Based Access Control Feature Information

IP Source Routing is enabled, which is a deviation from the router security hardening best practices

PAD (packet assembler/disassembler) service is enabled, which is a deviation from the router security hardening best practices

MOP (Maintenance Operations Protocol) Service is enabled, which is a deviation from the router security hardening best practices

IP Bootp Server is enabled, which is a deviation from the router security hardening best practices

Found missing router security best practices

Improve the Security Posture of the Device by Disabling Telnet

Evaluation period left

The data from this device was evaluated against 992 different diagnostic checks.

This script should capture the high cpu when it reaches over 70% and put it in flash

event manager applet High_CPU

    event snmp oid 1.3.6.1.4.1.9.9.109.1.1.1.1.4.1 get-type exact entry-op ge entry-val "70" exit-time 10 poll-interval 5

    action 0.1 syslog msg "CPU Utilization is high"

    action 0.2 cli command "enable"

    action 0.4 cli command "show log | append flash:CPU_Profile.txt"

    action 0.5 cli command "show process cpu sorted | append flash:CPU_Profile.txt"

    action 0.6 cli command "show interfaces | append flash:CPU_Profile.txt"

    action 0.7 cli command " show ip cef switching stat | append flash:CPU_Profile.txt"

    action 0.8 cli command " show ip traffic | append flash:CPU_Profile.txt"

    action 0.9 cli command " show int switching | append flash:CPU_Profile.txt"

    action 1.0 cli command "no event manager applet High_CPU"

    action 1.1 cli command "end"

[Marcio Ciano]

Hi Sreeraj. I had similar issue when the traffic over the GRE tunnel reaches 8M or above. I reserched and found out that this is a limitation bandwidth on GRE tunnel. As a workaround to avoid high CPU I put a rate-limit in 8M. HTH Marcio Ciano

[Joseph W. Doherty]

Marcio, could you provide any links to the information your research uncovered that further describes a 2900 tunnel running at more than 8 Mbps causes high CPU?

[Marcio Ciano]

Hi Joseph, I found the information on links below, not exactly related to 2900 series, but for my case (2911 and 1941) it seems happen the same. https://supportforums.cisco.com/t5/wan-routing-and-switching/gre-bandwidth-restriction/td-p/2682012 https://supportforums.cisco.com/t5/wan-routing-and-switching/gre-tunnel-max-bandwidth/td-p/1400841

[Joseph W. Doherty]

Thanks.