I've recently installed a new 6807XL Chassis in VSS in my datacenter.
After 3 weeks, I keep seeing the CPU usage around 25% (per second, per minute or per five minutes). Looking at the historical graphs I can see this has been the case since starting up the VSS.
When I try to see which process is consuming the most I can see slcp process at 4% – this is the highest. Next I get Spanning-tree at 2%…
I don't run much on the VSS, just static routes, a bit of OSPF, and the VSL link of course. I have around 10 000 clients connected on this VSS core which does the routing & switching. I also have 3000 lines of IP Access lists which all log matches & denies.
The IOS version is 15.1.2.SY1 (ipservices)
Should I be worried about this kind of percentage? To my knowledge, the correct values are usually down to 5%
Edit 1
My CPU Historical Graph:
> C6807XL-VSS#sh processes cpu history
2222222222222222222222222222222222222333332222111111111122
2244444444441111144444111118888833333111110000999996666666
100
90
80
70
60
50
40
30 ***** ***** **
20 **********************************************************
10 **********************************************************
0....5....1....1....2....2....3....3....4....4....5....5....
0 5 0 5 0 5 0 5 0 5
CPU% per second (last 60 seconds)
3422233233322849923322333224333573266433373354325244247744
1098420831256725241569234573112169569008255000763746619972
100 *
90 * **
80 * ** * * **
70 * ** * ** * **
60 * ** * ** * **
50 * ** ** ** * * * * *#*
40 * **** * * *#* *** * #* *** * ** *##**
30 **** ********#*## *********#**####*###*#*##*###***#***###*
20 ##########################################################
10 ##########################################################
0....5....1....1....2....2....3....3....4....4....5....5....
0 5 0 5 0 5 0 5 0 5
CPU% per minute (last 60 minutes)
* = maximum CPU% # = average CPU%
7544443444498577696877374645464538498648877789864645674549987888787878
9132939110527897235108828159076475618796321950899129812884364035733681
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%
Edit 2
CPU consumption:
Peak:
CPU utilization for five seconds: 48%/29%; one minute: 27%; five minutes: 24%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
302 37851048 3231408 11713 3.43% 2.23% 2.10% 0 SEA write CF pro
685 37324288 36021905 1036 2.79% 2.22% 2.11% 0 Spanning Tree
16 11694012 124309950 94 1.67% 0.97% 0.92% 0 ARP Input
171 25299104 2761699 9160 1.59% 1.34% 1.35% 0 OIR Process
188 71498212 166026936 430 1.43% 3.87% 3.97% 0 slcp process
74 2099116 167699 12517 1.43% 0.17% 0.11% 0 Per-minute Jobs
679 9251792 125616676 73 1.11% 0.90% 0.89% 0 IP Input
937 7254584 80249801 90 0.87% 0.44% 0.42% 0 Port manager per
922 453432 99151 4573 0.87% 0.07% 0.01% 0 CM hw consistenc
699 3728624 5213752 715 0.63% 0.40% 0.37% 0 mDNS
<...output truncated...>
Low:
CPU utilization for five seconds: 29%/9%; one minute: 26%; five minutes: 24%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
188 71499092 166028826 430 5.51% 3.94% 3.98% 0 slcp process
302 37851672 3231454 11713 2.63% 2.22% 2.11% 0 SEA write CF pro
685 37324828 36022200 1036 2.39% 2.30% 2.14% 0 Spanning Tree
171 25299392 2761729 9160 1.59% 1.35% 1.35% 0 OIR Process
679 9251960 125618970 73 1.19% 0.87% 0.89% 0 IP Input
16 11694192 124312162 94 1.11% 0.94% 0.91% 0 ARP Input
907 8811320 2294505 3840 0.95% 0.48% 0.47% 0 Env Poll
937 7254672 80250797 90 0.63% 0.43% 0.42% 0 Port manager per
699 3728724 5213875 715 0.47% 0.42% 0.38% 0 mDNS
744 7597964 8291508 916 0.39% 0.44% 0.42% 0 XDR receive
<...output truncated...>
Best Answer
What you have experienced is most likely one of the bugs below. We've had exactly the same problems and had it all fixed when upgrading to 15.1(2)SY7. It's a copy/paste from Cisco bug report:
We had the problem with the first bug, since we used 10G SFP's in the Supervisor to create the VSS VSL. The second bug was also pretty common and i've heard a lot of people have problem with it.
Cisco Bug: CSCur96442 - C6800: High CPU due to "slcp process" when 10G ports have 10G SFPs
Last Modified
Oct 01, 2018
Products (1)
Cisco Catalyst 6000 Series Switches Known Affected Releases 15.1(2)SY5.1
Description (partial) Symptom:
Catalyst 6800 platform reported elevated usage of CPU due to "slcp process". CPU utilization vary based on number of 10G ports used. More the number of ports used, more the CPU usage seen. Example:
Conditions:
This defect is applicable only when the 10G ports use 10G transceivers. E.g., SFP-10G-SR, SFP-10G-LR, SFP-10G-LRM
High CPU is NOT seen when the 10G ports are admin down.
Cat6800: High CPU usage due to "slcp process" when GLC-T plugged in
Description Symptom:
Catalyst 6800 platform reported elevated usage of CPU due to "slcp process". CPU utilization vary based on number of 1G ports used. More the number of ports used, more the CPU usage seen.
Example:
Conditions:
This defect is applicable only when the 1G ports use GLC-T transceivers
Workaround:
If GLC-Ts are not used shutdown the interface to reduce the CPU load.
Further Problem Description:
Fix introduced to address this issue optimizes the CPU cycles used to poll the transceivers and get data/stats. It essence, the fix reduces the CPU usage approximately by 50% and will not bring down the CPU usage to 0.
For similar issue reported for 10G SFP, please refer CSCur96442