I'm moving a box that's running ESXi into a server colocation room at a local ISP. This box has a few virtual machines on it, and the local ISP just provides 1 IP address (by default).
Is there any problem in running a pfSense (or similar, suggestions?) VM as the gateway to my other VMs behind this pfsense NAT? My concern is that since the pfSense box will be routing traffic for multiple VMs (that will all be running on the same physical machine) we'll run into some performance issues.
The traffic should be relatively low, at least in the beginning. Something like a simple web-server and a Ventrilo server with < 50 users at any given time.
I wouldn't worry about performance issues with routing vm traffic internal to vmware. You should exceed performance over the same systems with physical connections
I did something similar to this using a project called Vyatta (which I highly recommend). It's been a while, so I don't remember the specifics, but it wasn't particularly difficult to do. You just have to have the virtual NICs for the "LAN" side devices all be members of a common vswitch. Performance was phenomenal and the resources assigned to the Vyatta VM were fairly minimal. I believe Vyatta refers to such a solution as a "branch in a box".