Under The Covers
When I first received the Sonos package, I was only slightly familiar with its capabilities, and as I set it up, I was puzzled. It clearly had wireless capabilities, but there was no configuration necessary to get the three components - two of which were wireless - talking to each other. Digging deep into the menus I did find a setting for selecting which wireless channel would be used, but everything came up and worked fine on its own. I guess this is the way things should work.
The Sonos Website offered some answers. The Sonos system apparently uses "Sonosnet," which is an AES encrypted peer-to-peer mesh 802.11g-based networking system. You will not see any Sonos components show up on your list of available access points and the system automatically tries to find an open 2.4 GHz channel for itself so as not to interfere with other networks.
A scan of my network turned up three new IP addresses showing that each device was a little stand-alone computer in its own right. A port-scan of each of the devices turned up nothing interesting except what appeared to be an open UPnP port running on a Linux kernel. Sonos has a GPL download page that identifies specific GPL components as well as the Linux kernel version used.
I have a UPnP client on my network, so I was interested to see how it would react to the ZP80 servers. When I turned on my client, both servers showed up and I could navigate deep into their menus to see directory structure, artist name, album names, etc., but I couldn't get the actual music.
There must be something unusual about how Sonos is using UPnP. Since Sonos servers showed up was also a bit of an aggravation. The long server names "192.168.1.114 - Sonos ZonePlayer Media Server" cluttered up my device's source selection menu and served no purpose. I could not use them, and I could not remove their names from the menu.
At this point in the review, I normally pop off the cover of the device under review and take pictures of the main board. But with these expensive devices using smooth plastic cases and hidden screws, I was not willing to risk marring the case by prying them apart, so I had to rely on what I dug up on the Internet to tell me what was inside.
According to most of the info I saw, the CPU Sonos used for these devices is a Renesas SH-4 processor. I also found a group working on creating custom extensions to the Sonos device, but unfortunately they are doing most of their software in .NET, which will limit its audience.