Atom CPU N270 or 330 good enough for FiOS link with VPN and FreeSwitch?
The subject says most. I'm trying to replace a few ZyWALL 5 UTM systems with either Intel Atom N270 based netbooks (single-core 1.6GHz CPU w/ hyperthreading and 2GB RAM), or some Intel Atom 330 based system (dual-core 1.6GHz CPU with hyperthreading and 64-bit support, and 2GB RAM), each with a built-in Gigabit ethernet adapter, plus a couple of Asix-based USB2 ethernet adapters.
The internet link is a FiOS link with 20mbit/s max. There will be one or more VPN links active at all times (one may even use a NULL encryption, since it just acts as a tunnel for re-routing purposes, the others should use AES256 or something similar).
I'd love to have the FreeSwitch module installed, too. Goal here is to have it act as a small PBX with maybe 2-3 active phone conversations max.
Is this a realistic load on the proposed systems, or would I need something beefier?
The Atoms are attractive due to their rel. low power requirements. A Netbook, while only single-core, would have the added benefit of having a "built-in UPS" (aka laptop battery).
As long as Freeswitch isn't transcoding, the load from phone calls should be next to nil. An Atom can be compared roughly clock for clock with the Pentium 3, so as long as you give it sufficient RAM (which is dirt cheap, so you may as well give it 2GB no matter the need) it'll power through 20mbit/sec of VPN and phone switching without a complaint. I'd doubt you'll even see load averages over .3 under most use.
For reference, I operate an enterprise scale SIP softswitch supporting roughly 30,000 users. The hardware for the "network server" which is the part that handles basically what Freeswitch or Asterisk would be doing is a single IBM blade with a single 2.83GHz Xeon quad core and 4GB of RAM. That machine is overspecced by a long shot for the actual needs, hardware's just so cheap that there was no point in getting a smaller box.
According to some benchmark utilities, my laptop (Macbook Pro, 2.4GHz "Penryn" Core 2 Duo dual core, 4GB RAM) is capable of being a softswitch for about 20,000 users without exceeding 70% load. Softswitching is basically like routing, only it doesn't need to be nearly as fast or do it nearly as often, so the load on a per user basis is trivial. It takes more computing power to be a router for a 2MB file transfer than an SIP softswitch for an average medium-sized business in a day.
Converting between codecs and playing/recording media are where it begins to actually take some CPU time.
With the specs you gave FreeSWITCH will easily work with 2-3 calls even with transcoding. Without transcoding with the specs you mentioned you could likely get 20-30 calls on the system and possibly more.