Firewall

During the install process it is very important that you choose the option to include the Firewall rules for AppFabric (see red box in below screenshot).

AppFabric Server Configuration Wizard

However, even with these in place you still have Firewall problems if Ping is not enabled—your cache nodes cannot communicate.

An easy way to determine this is to run “Get-CacheHost and see if any nodes’ statuses come back as “Unknown” (as seen in the below screenshot).

This can be an indication of other network problems of course, but it definitely shows this way if you have the problem I am describing.

The ping command uses the ICMP protocol. So, you need to add an inbound rule on all of the servers in your cache cluster to allow incoming ICMP traffic. Once I did this, my three cache nodes could communicate with one another as expected.