[c-nsp] Huge SP CPU usage spikes 100%

[Sven Simonsson]

It is expected to have something like  30% SP CPU due to the diagnostics tests that run on the LCs.

Excessive SP CPU usage is typically related to Layer 2 operations like STP, IGMP and LACP.

But another root cause of SP CPU running wild can be HSRP on multiple SVIs. If this applies - have You set priority? Do You use preempt?

Applied "no ip proxy-arp" on SVIs? "no ip redirects"?

You may also try to disable the diagnostic monitoring of LCs and verify outcome. 

switch(config)#no diagnostic monitor module all
switch(config)#end
switch#remote command switch show proc cpu hi

Cheers
Sven