A couple of weeks ago I have been experiencing high CPU usage in my GNS3 home lab. After some trial and error, I localized the issue and discovered that the cloud device connection is the cause.

My old topology

I have a cloud device connected to a hub. The hub connects to the HQ router and the Unified Border Element. At some points in time, I hear the laptop fan working hard. This was not like that before adding the Unified Border Element. I think if you add more than two devices to a hub, your CPU will suffer.

So my old trick for this high CPU usage was to disconnect and re-connect the cloud device to the hub. However, one time out of three I get the gns3 waiting for error. And my GNS3 setup crashes.

My new topology

I was thinking of getting rid of hubs. I tried a switch. But it did not establish cconnectivity between connected devices despite they were on the same vlan (GNS3 bug?)

Then I thought about putting a multilayer switch and doing the right routing configuration to make things work. So I had to segment the network into three subnets and route between them.

It did the job.

gns3-high-cpu-utilization-hub---2016-06-17 08_51_12

Categories: Home Lab

Keyboard Banger

Keyboard Banger is a network engineer from Africa. He has been working in network support and administration since 2008. He started writing study notes about certification exams and technology topics a couple of years ago. When he's not writing articles, he can be found wandering on technical forums.


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