High CPU Utilization

ladopetrucci · ‎02-28-2017

Hello all,

I have problem with my router cpu utilization. I'm trying to find what is causing this, but still nothing,

Router is cisco 2921/K9 with IOS c2900-universalk9-mz.SPA.152-4.M6.bin

this is output of trouble shooting commands, what i read in documantation

MainOffice#sh processes cpu sorted | exclude 0.00%
CPU utilization for five seconds: 75%/67%; one minute: 64%; five minutes: 66%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
59 600 25 24000 4.00% 0.32% 0.06% 389 SSH Process
13 1604288 10355 154928 1.19% 0.14% 0.07% 0 Licensing Auto U
378 3000348 132492389 22 0.47% 0.60% 0.60% 0 IP SLAs XOS Even
3 5300 6026 879 0.31% 0.15% 0.06% 388 SSH Process
122 5883044 11746336 500 0.31% 0.28% 0.29% 0 IP Input
32 1667076 10199140 163 0.15% 0.14% 0.15% 0 ARP Input
129 879528 72885622 12 0.15% 0.21% 0.21% 0 Ethernet Msec Ti
293 854100 1571839 543 0.07% 0.03% 0.02% 0 Crypto IKE Dispa
106 1951816 2485787 785 0.07% 0.14% 0.15% 0 Netclock Backgro
126 290972 9618027 30 0.07% 0.04% 0.05% 0 VRRS Main thread
196 429996 941988 456 0.07% 0.03% 0.02% 0 CEF: IPv4 proces
119 650884 1242299 523 0.07% 0.03% 0.02% 0 BPSM stat Proces
294 856608 2306297 371 0.07% 0.07% 0.07% 0 Crypto IKMP
166 356948 18765391 19 0.07% 0.04% 0.05% 0 IPAM Manager

MainOffice#show ip cache flow
IP packet size distribution (369878621 total packets):
1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480
.000 .529 .020 .017 .041 .007 .014 .007 .008 .013 .006 .005 .004 .003 .003

512 544 576 1024 1536 2048 2560 3072 3584 4096 4608
.002 .002 .002 .017 .289 .000 .000 .000 .000 .000 .000

IP Flow Switching Cache, 0 bytes
0 active, 0 inactive, 4192949 added
64819760 ager polls, 0 flow alloc failures
Active flows timeout in 30 minutes
Inactive flows timeout in 15 seconds
last clearing of statistics never
Protocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec)
-------- Flows /Sec /Flow /Pkt /Sec /Flow /Flow
TCP-FTP 89 0.0 11 69 0.0 2.2 7.9
TCP-WWW 463531 0.7 34 77 25.9 4.3 8.8
TCP-SMTP 246 0.0 402 1281 0.1 1.6 15.2
TCP-X 4 0.0 4 99 0.0 0.6 8.9
TCP-other 1979693 3.1 137 412 436.2 7.3 11.4
UDP-DNS 441772 0.7 1 70 0.7 0.2 15.7
UDP-NTP 6363 0.0 1 84 0.0 0.0 15.6
UDP-TFTP 5 0.0 2 50 0.0 3.9 15.6
UDP-other 1219269 1.9 8 232 16.0 2.0 15.6
ICMP 22288 0.0 4 64 0.1 2.4 15.4
IP-other 59662 0.0 1195 935 114.5 45.8 15.4
Total: 4192922 6.7 88 493 593.8 5.2 12.9

SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts

MainOffice#show cef drop
% Command accepted but obsolete, see 'show (ip|ipv6) cef switching statistics [feature]'

IPv4 CEF Drop Statistics
Slot Encap_fail Unresolved Unsupported No_route No_adj ChkSum_Err
RP 0 0 6888037 41 1328136 68

please if you can to help to solve this problem

Philip D'Ath · ‎02-28-2017

The issue is the high interrupt time, at 67%. This is related to traffic being forwarded - and there is usually nothing wrong.

What it means is you need a higher spec router with greater forwarding capacity for the traffic load offered. Your current router does not have sufficient capacity.

If you have all Ethernet interfaces, and are only doing packet forwarding you could consider changing to a layer 3 switch, like a Cisco 3850.

Otherwise consider looking at the Cisco 4000 series. Good candidates could be the 4331 or the 4431 (based on you having a 2921 at the moment). The 4000 series give you specific levels of performance, and both of these models have an option to buy a licence which increases the performance further.