Recently, we pointed to the many flavors of IP network services that can legitimately be called "IP VPNs." And you've likely heard that frame relay, Multi-protocol Label Switching and metro Ethernet industry groups are forging cooperative ties to foster interoperability at the network "plumbing" level.\u00a0These developments reflect the fact that the method by which bits are transported is starting to take a back seat to what you get in an overall service description. Higher-layer application services, outsourcing\/managed CPE services, a carrier's financial stability, customer support, and other, more distinguishing factors, will carry the greatest value to you going forward as parity and interoperability among the network transport options is achieved.Here's a recap of recent industry developments:* In late January, the Frame Relay Forum and the MPLS Forum proposed a merger, which is expected to yield a combined organization called the MPLS and Frame Relay Alliance by late March. The combined group will reportedly focus on frame relay-to-MPLS interworking and will also cooperate with the Internet Engineering Task Force on efforts such as the Martini Draft for supporting legacy data services over MPLS core networks.* In mid-December, the MPLS Forum and Metro Ethernet Forum said they would start sharing work in progress and produce joint technical specifications. For example, MPLS Forum chairman Andrew Malis has noted that service interworking between Ethernet endpoints and MPLS networks is on the to-do list. This technical concept parallels the spirit of the Frame Relay Forum's FRF.8 spec for service interworking between frame relay endpoints and ATM endpoints-enabling the mix-and-match of various customer access interfaces with the service provider's backbone protocol.* In October, the MPLS Forum approved the MPLS Permanent Virtual Circuit User-to-Network Interface (PVC UNI) implementation agreement. The MPLS PVC UNI specifies a standard interface to a public MPLS VPN service with quality-of-service characteristics in subscriber equipment.Bottom line? Transports are becoming interchangeable, making life easier for enterprise network buyers, who can focus on more strategic considerations.But where is the ATM Forum is in all this? Most service provider backbones migrating to MPLS are based on ATM, so it would seem important for those two technology groups to come together. And yes, many of you use frame relay interfaces to IP VPN services (also called "IP-enabled frame relay"), but IP-enabled ATM services are available, too.