Dual Ethernet, Dual Web/Sip Server

Hi folks,

(I'm not actually new here, I have another forum username but apple refused to allow me into the forum with it, that's a whole 'nother problem though).

I currently have a Mac Mini Server set up with a whole bunch of services (mail, address book, AFP, web, etc). On this server I also have an IP-PBX which I am in the process of configuring (a Snom One PBX). The PBX is running on port 8080 and other alternates so that its web interface does not conflict with the web server. However the problem I'm having is setting up QOS for the VoIP data. I'm trying to put the PBX on a separate VLAN than the server proper. I bought a USB ethernet adapter thinking I could run the server traffic off of that and run the PBX traffic off of the internal ethernet, but I can't figure out how to do that.

Does anyone know if this is possible or practical? If so, how to accomplish this?

Thank you.

Hal