Core Issue
These are common symptoms of high CPU utilization:
- High percentages in the output of the show processes cpu command
If you have the show processes cpu command output or a show tech-support command from enable mode, display potential issues and fixes from your Cisco device by referring to the Output Interpreter tool.
- Input queue drops
- Slow performance
- Services on the router fail to respond, for instance:
- Slow response in Telnet or unable to Telnet to the router.
- Slow or no response to the ping command.
- The router does not send routing updates.
If the router is being overloaded with traffic or the traffic not taking the optimal switching path through the router, the issue can also be caused by the Blaster and Nachi worms.
- You can see what are the processes shooting your CPU utilization using following command:
Router#sh processes cpu | exclude 0.00%__0.00%__0.00%
CPU utilization for five seconds: 2%/100%; one minute: 1%; five minutes: 1%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
2 8 13918 0 0.00% 0.02% 0.00% 0 Load Meter
5 66924 8516 7858 0.65% 0.10% 0.06% 0 Check heaps
20 10148 19914 509 0.00% 0.02% 0.00% 0 HC Counter Timer
30 3980 25100 158 0.00% 0.01% 0.00% 0 Net Background
33 1768 69568 25 0.00% 0.01% 0.00% 0 TTY Background
34 3912 69584 56 0.00% 0.02% 0.00% 0 Per-Second Jobs
64 12556 2172687 5 0.24% 0.21% 0.19% 0 ACCT Periodic Pr
68 12240 2172686 5 0.16% 0.17% 0.18% 0 IP ARP Retry Age
78 1088 271810 4 0.08% 0.02% 0.00% 0 SSS Feature Time
92 16732 86322 193 0.00% 0.06% 0.04% 0 CEF process
108 6856 69572 98 0.00% 0.01% 0.00% 0 RUDPV1 Main Proc
110 2364 69574 33 0.00% 0.01% 0.00% 0 bsm_xmt_proc
114 12892 1161 11104 0.00% 0.01% 0.00% 0 Adj Manager
127 5600 695694 8 0.08% 0.10% 0.09% 0 RBSCP Background
130 5392 854 6313 0.98% 0.30% 0.12% 0 Exec
220 46188 13920 3318 0.00% 0.05% 0.07% 0 Compute load avg
- You can also check your CPU history in graphical pattern using "show processes cpu history" command to see High CPU spike.
Router#show processes cpu history
Router 07:25:36 PM Friday Mar 1 2002 UTC
2222233333 1111111111
100
90
80
70
60
50
40
30
20
10
0....5....1....1....2....2....3....3....4....4....5....5....6
0 5 0 5 0 5 0 5 0 5 0
CPU% per second (last 60 seconds)
11111221113111111111111111112121111111111 221111111111111111
100
90
80
70
60
50
40
30
20
10
0....5....1....1....2....2....3....3....4....4....5....5....6
0 5 0 5 0 5 0 5 0 5 0
CPU% per minute (last 60 minutes)
* = maximum CPU% # = average CPU%
4 11
2322333222232223425
100
90
80
70
60
50
40 *
30 *
20 *
10 * ** *
0....5....1....1....2....2....3....3....4....4....5....5....6....6....7..
0 5 0 5 0 5 0 5 0 5 0 5 0
CPU% per hour (last 72 hours)
* = maximum CPU% # = average CPU%
Router#
Resolution
To resolve this issue, determine the accessibility of the router by performing these steps:
- Determine if you are able to issue the show commands on the router. If so, start collecting more information immediately using these show commands.
- Determine if the router is inaccessible and if this problem is reproducible. If so, power-cycle the router. Before reproducing the problem, configure the scheduler interval 500 command; this schedules low priority processes to run every 500 ms. This provides time for you to run some commands, even if CPU usage is at 100 percent. On Cisco 7200 and Cisco 7500 series routers, issue the scheduler allocate 3000 1000 command.
- Determine if the router shows symptoms of high CPU utilization at brief and unpredictable intervals. If so, periodically collect the output of the show processes cpu command. This shows if the high CPU utilization is caused by interrupts or by a certain process. Use this UNIX script. Based on the first findings, modify the script to collect data needed for further investigation of the issue.
For more information, refer to Troubleshooting High CPU Utilization on Cisco Routers.
To determine if your problem is related to worms, refer the document High CPU utilization on a router