High CPU loads Cisco 2960

Lately I have been working a lot with Cisco 2960 access switches, with different IOS versions. I noticed that the C2960-48TC-L and C2960-48PST-L types had high cpu loads. After contacting Cisco it looks like it’s not a bug, but a “feature”.

On the switch there is a process called “Hulc LED process”. In short this proccess is responsible for link detection. When a switch has al it’s ports with the “connected” status there is no problem. If one or more  ports has it’s status “not connected” the process spikes up to 80%.

Cisco’s solution after reading the official Cisco forum: the process as mentioned above is working as designed and if you want to temper the cpu load, manually shutdown the “not connected” ports.

I think it’s a really crappy answer because a not connected port can have a turned off computer behind it.

Nevertheless the solution works. After manually shutting down the “not connected” ports the process cpu load drops to normal values.


One Response to High CPU loads Cisco 2960

  1. Sasha says:

    Thanks for sharing. We have the same problem on 2960s stack. But there are only 2 interfaces in “not connected” state. Could it be a reason of about 20% Hulc LED Process.

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