On the heels of announcing that it intends to layer a voice over IP option to its managed IP VPN services throughout 40 countries during 2004, AT&T added another managed offering to its Ethernet services portfolio.The AT&T Ethernet Switched Service-Metropolitan Area Network service is a mesh, transparent LAN service that interconnects your business sites. Franco Callocchia, AT&T Ethernet services director, describes it as a "switched Ethernet VPN service for metropolitan, local and regional connectivity."The service is available at 50M to 1G bit\/sec speeds in 67 metro areas, which translates into about 90 cities and 6,400 office buildings. Callocchia says AT&T can deploy dedicated fiber and managed CPE (a 10\/100 or Gigabit Ethernet switch) on your behalf. Or, the carrier can use an existing SONET infrastructure, in buildings where it is already in place, and layer the service on top of that. In the second case, your Ethernet traffic would be encapsulated in SONET, then de-encapsulated at the other end.It's getting a tad difficult to distinguish among the six flavors of Ethernet services that AT&T provides. These include Ethernet-to-Internet access connections and Ethernet point-to-point metro and long-haul services.The good news, of course, is that there are growing Ethernet alternatives out there for those of you needing the large pipes and scalable bandwidth afforded by Ethernet technology. Witness, for example, another encouraging development: Ethernet service provider Yipes completed its $9.5 million Series A equity investment, totaling $63.5 million, last month.Ethernet service options tend to be clustered in the same places. Understandably, they exist in large metro areas with highly populated buildings that justify the installation of local fiber networks. At some point, though, there will be an overabundance of options for these sites, but precious few for out-of-the-way locations. This will pose challenges to enterprises looking to run back-up data centers - if not primary sites - in places where real estate is more affordable, if more fiber or emerging copper-based alternatives do not appear.Next time: a few more words about Ethernet service reliability in general and AT&T's offering in particular.