Looking for a solution to fix high CPU usage on Cisco routers?

by Aleksandar Ognjanovic
Aleksandar Ognjanovic
Aleksandar Ognjanovic
Troubleshooting Expert
Aleksandar's main passion is technology. With a solid writing background, he is determined to bring the bleeding edge to the common user. With a keen eye, he always... read more
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The high CPU usage on a Cisco router is rather uncommon. If you’re configuring routers frequently, you’ll know that CPU utilization will rise when transferring files between segments.

However, what happens if the usage is at skyrocketing at all times? Well, we can provide you with some initial information, but for the sake of troubleshooting, check the Cisco official support side or try your like with the community experts.

How to reduce CPU usage on the Cisco routers

First of all, make sure that your router is capable of handling multiple ports before going for any troubleshooting steps. If you’re positive that it can deal with the workload, you can try some of the common steps.

Even though initially sounds like a good idea, we suggest avoiding the half-duplex communication.

What you can do is drop down the load interval to 30 seconds and downgrade the configuration from 100 MBps to 10 MBps.

If that doesn’t help, here’s the list of possible culprits for high CPU usage:

  • Inappropriate switch path
  • All load of alignment corrections falls on CPU
  • Traffic overload
  • Bug in Cisco IOS
  • Configured voice ports
  • ATM interfaces are active on the router
  • Too many packets are being punted from PXF to RP.

These are usually causing the problem with CPU utilization and we can’t say with certainty what is the exact problem. What you need to do is follow through with the thorough inspection until you find the problem.

If you’re still unable to locate the problem, we suggest contacting the official support and asking for some assistance.

Moreover, if you’re aware of a certain solution, feel free to share it in the comments section below with the rest of our readers.


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