05-29-2012 01:20 AM - edited 03-04-2019 04:29 PM
Hi,
I have a small network of 4 x 3750s running routing (OSPF) which contain all company firewalls. It bridges internal trusted corporate networks (depots etc) to external untrusted networks (Internet/Datacenter networks). It sees a fairly high level of traffic running through it (it gets forwarded to firewalls at gig speed).
OSPF is costed to remove asymetric routing so one 3750 is acting as primary and does most of the work. The 3750s are in area 0, and all other areas are summarised to some degree. However, CPU is running high on the 3750 when looking at the history at times:
PPFX_X37_274#sh ip ro summ
IP routing table name is Default-IP-Routing-Table(0)
IP routing table maximum-paths is 32
Route Source Networks Subnets Overhead Memory (bytes)
connected 0 3 192 456
static 53 549 90816 91504
ospf 1 13 1945 128768 297616
Intra-area: 67 Inter-area: 903 External-1: 983 External-2: 5
NSSA External-1: 0 NSSA External-2: 0
internal 22 25784
Total 88 2497 219776 415360
PPFX_X37_274#sh proc cpu | exc 0.00
CPU utilization for five seconds: 26%/18%; one minute: 26%; five minutes: 26%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
4 93091018 6079803 15311 0.95% 0.18% 0.14% 0 Check heaps
129 16401387 75768455 216 0.15% 0.04% 0.03% 0 HL3U bkgrd proce
184 81753329 515763429 158 0.47% 0.19% 0.16% 0 IP Input
290 66535786 35750699 1861 0.47% 0.24% 0.17% 0 SNMP ENGINE
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%
My question is - although the average is around 26% the 72hour picture would suggest that CPU is running at 100% at times. Is this an imminent concern that needs re-designing, or is this normal behaviour (SPF running for instance) that is manageable?
thanks
Phil
05-29-2012 01:37 AM
Hello Phil,
Can you also have a look at show processes cpu sorted ? Try out also 1min and 5min keywords to see what processes tend to create a long-standing load on your CPU. This command should place the most CPU-intensive tasks at the top of the listing so you can see what process is consuming most of your CPU time.
Having a load in the range of 26% is, in my personal opinion, nothing to be especially concerned about, but I do not quite like the spikes up to 100%. They need more investigation indeed.
This may look like trying to solve your issue quickly but I really recommend going through the following documents:
http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/troubleshooting/cpu_util.html
http://www.cisco.com/en/US/products/hw/switches/ps5023/products_tech_note09186a00807213f5.shtml
They describe some of the most common causes very nicely. Please do inform us about any issues you will find out!
Best regards,
Peter
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