Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

High values of CPU on our router.

Hi all,

we have router Cisco 3660 and we observe

last time high values of CPU on our

router. It happens only when we do backups. Maybe once per week.

CPU rises up to 90 % and big traffic is

only on interfaces from and where are

backups transmited. From our monitoring system we see on interfaces cca 30MB load.

So is it possible to tune this load?

Or should we upgrade IOS?

Any suggestions?




Re: High values of CPU on our router.

It seems as if the load is due to your backup pushing the specifications of the router. Do you have CEF enabled? If not then try enabling cef (ip cef) and see if that helps.

New Member

Re: High values of CPU on our router.


If we enable ip CEF ,WHAT IS benefits of this?

and which command should be enable under the interface.ip route-cache? or we should disable the no ip route-cache.?whai is the best?



Re: High values of CPU on our router.

CEF is currently the recommended switching path and should be used always unless some feature is required that is not supported by CEF. The major advantage of enabling CEF is that it is less CPU intensive when compared to fast switching which directly improves the performance of your router. Once you enable it globally using the 'ip cef' command it will automatically be activated on all CEF supporting interfaces.

Re: High values of CPU on our router.

hi ali,

CEF is cisco express forwarding...its provide the very high speed switching of maintain the FIB and aducancy table in order to achive the fast data transfer...FIB is same as our routing table and adjucany table havig hardware address CEF first packe to the destination is forwarded by the layer 3 software base lookup and then all the subsequence packet will send by the rewrite the packet using ASIC which make it faster...its also use full when you are having more cpu usage.. .

hope this will help you

rate this post if it helps



CreatePlease to create content