I´d like to know if you can give ideas od what may happen with one 7500 router CPU, that 3 months ago suddenly increased to over than 25% of it currently use. Unfortunely, i don´t have data logged at the time of the change, but now i am trying to figure out what happen, the cpu seens to be acting normal, most of the time busy doing switching and rounting , cause the use of cpu is mostly due to interrupts, i mean, when i submit the "sh proc cpu" command i normaly see that the "X/Y" value at the first line of the output are very similar values, that just differ 1 or 2% each other.
If you have any clue of what could happen one day to another to make the cpu increase that much, please let me know,
Without any information, as to what the routers function is/protocols running/etc it would be a shot in the dark as to what caused a 25% CPU spike. If your router is doing a lot of interupt level proc then it might have been traffic related. Depending on the routing protocols you're running (i.e. OSPF/BGP) it could have been severe churn with them that also could efftect your CEF proccess. List goes on and on. If you can identify the specific process that took this extra 25% someone could surely help ID the root cause for you.
Without much information on the traffic patterns, it is difficult to give a definite answer. This definitely looks like traffic has increased in your network. Has there been any additions recently or changes in applications ? You could try to offload part of the CPU load to the VIP cards (if you have any) and use distributed CEF switching ('ip cef distributed' in global config mode).
You could also use the command: 'show interface switching' to see from which interface you have the most traffic. That could give you some indications/hints as to what is causing the increase in CPU.
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