The APIC is the core component for ACI. All configuration will be issued and maintained from this system.
After the login the dashboard is being presented – will give you an overview on system health and some statistics.
![](https://7o9.de/wp-content/uploads/2020/06/image-37-1024x654.png)
In our simulator we’ve got only one APIC, in production setups there have to be at least three nodes. That’s why you will see constantly in your simulator a warning in your notification field.
![](https://7o9.de/wp-content/uploads/2020/06/image-35.png)
Three nodes to avoid the risk of cluster fragmentation (sometimes called „split brain“).
Briefly explained – if there are only two nodes acting as APIC, and they will lose connectivity – there is no way to decide for the now isolated APIC, if the other node is down or just not reachable. Worst case scenario for this failure – both nodes are guessing, the other one is down, and that way the configuration will differ.
To avoid this situation the solution is to provide a n+1 requirement. Means – only if a node is part of a majority, than this node will continue to run. So – if e.g. apic1 and apic2 are having connectivity, but apic3 hasn’t, apic3 will cease operation.
After login you’ll find many tabs and sub-tabs. We’ll just go briefly through them.
At the top right there are four icons, the second from the right expands to:
![](https://7o9.de/wp-content/uploads/2020/06/image-36.png)
Nice – Change My SSH Keys – here you are able to store the public key from your jump server (if you are using one).
After deploying – the passwordless ssh-key based access is working. Automatically on all nodes.
iMac:~ andreasfassl$ ssh -l admin 192.168.140.40
Application Policy Infrastructure Controller
Last login: 2020-06-18T14:08:12.000+00:00 UTC
apic1#
Connection to 192.168.140.40 closed.
iMac:~ andreasfassl$ ssh -l admin 192.168.140.41
admin@leaf1:~>