Control High CPU Utilisation - Internet Router

[sreeraj.murali]

Hi,

I am attaching the show tech output from the Internet Router. Also, this Router is running as Backup GRE Tunnel. So, at normal scenario, the Router is only handling Internet traffic. Please let me know, what could be the root cause and remedy for mitigating for the same.

Thanks & Regards

Sreeraj

[Mark Malone]

Hi

you wont tell from that output resons being is CPU was captured when oit was low and needs to be captured in real time dureing the issue as below it was only at 8% when you ran the tech so can see which process jammed it up , but it definitely was highup looking athe history output

CPU utilization for five seconds: 8%/7%; one minute: 6%; five minutes: 9%
 PID Runtime(ms)     Invoked      uSecs   5Sec   1Min   5Min TTY Process

                                                                 
 --More--                                                                          
 --More--                                                                          
 --More--               9 1       377878858      668737776674672  47   678974      
 --More--               680877765849624145154575670556030767480544105473992745596477
 --More--           100 *                                                          
 --More--            90 *                          *                     **        
 --More--            80 *          *** ** *        **      *            ****       
 --More--            70 *          **#*** *      * ** ****** **    *    *##*       
 --More--            60 *          **#*****      **** ****** **    *   *###*       
 --More--            50 *          *##**#*#      #*#* *#**## **    *   *####       
 --More--            40 *          ######*#      #*#***#*###**#   **   *####*      
 --More--            30 *         *########      ###***#*###*##*  **   *####*      
 --More--            20 *         #########      ####*######*##*  *#   #####*      
 --More--            10 ##*******##########* ****##############*  ##* *######**** **
 --More--              0....5....1....1....2....2....3....3....4....4....5....5....6
 --More--                        0    5    0    5    0    5    0    5    0    5    0
 --More--                        CPU% per minute (last 60 minutes)
 --More--                       * = maximum CPU%   # = average CPU%

If your having an issue capturing it while it happens run and eem script and send it to flash automatically when it hits 70% like below , then you can extract the txt file and see the outputs collected

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"

[sreeraj.murali]

Thank you. Will check out.

[Joseph W. Doherty]

GRE tunnels can consume quite a bit of additional CPU if they have to deal with fragmentation.  You might want to review http://www.cisco.com/c/en/us/support/docs/ip/generic-routing-encapsulation-gre/25885-pmtud-ipfrag.html.

[sreeraj.murali]

Thanks for the inputs. Will check.