The Virtual Wall is hosted at and operated by imec IDLabt ilab.t. It actually consists out of 2 testbeds:

The hardware can be used as bare metal hardware (operating system running directly on the machine) or virtualized through openVZ containers or XEN virtualization. XEN Virtualization comes into two flavours: using shared nodes (non-exclusive) where VMs are running on physical hosts which are shared with other experimenters, or using physical nodes (exclusive) which are exclusively used by your experiment. You have full control on all XEN parameters as you have root access to the DOM0.

Network impairment (delay, packet loss, bandwidth limitation) is possible on links between nodes and is implemented with software impairment.

Multiple operating systems are supported, e.g. Linux (Ubuntu, Centos, Fedora), FreeBSD, Windows 7.

All nodes have by default a public IPv6 address, and you can ask through the tools (pools of) public IPv4 addresses to experiment with fully connected machines, build your own cloud or do big data analysis.

Some of the nodes are connected to an OpenFlow switch to be able to do OpenFlow experiments in a combination of servers, software OpenFlow switches and real OpenFlow switches.

You can check the number of free resources on each testbed at the Fed4FIRE+ Federation Monitor.