NSX : Communication Channels Down

As explained in a previous blog post, I’m working on NSX these days. I’m still performing some setup on my NSX Lab. 

The NSX lab is a nested one, with 4 ESXis.
One cluster for management, one for workload, 2 ESXis in each cluster.

I started to deploy NSX services on the management cluster and I had an issue when I deployed VXLAN.
One of my ESXi had an issue with communication channels, it was simply down :

My first idea is to check status of NSX services trough an SSH connection:

Netcpad is the daemon installed on the ESXi for the control plane, it allows communication with the agent in the NSX manager. It also communicates with the controller cluster. Thank’s to a periodic check we can have a status of these service in the NSX UI : the communication channels, where my issue is.
Service is running, in the NSX Manager, in my controller, and in my ESXI…

Next step is to check the vsfwd also know as “vShield Stateful Firewall” is this again we have the daemon.
Status : running… again no issue here.
But in the UI my communication channels is still down.
To be 100% sure that those services have no issue I tried to restart them :

Check in the NSX UI : Communication channel still down…

Next step: go on google  and search for some kb or blog post…

I find a solution for the same symptoms :
– Put the ESXi in maintenance mode
– Put the ESXi out of the cluster
– Reboot twice

And then here we are, everything green:

I still don’t really understand why I had this issue…
One of my thought is that I have a poor switch, which may have issue with 1500+ MTU.

I have a Cisco 3750 waiting to upgrade my homelab, maybe it will solve this kind of issue?

If you have other idea, feel free to ping me 😉

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