When choosing a MAN solution, you should consider cost, scalability, transparency, level of service, and type of connection(s) needed. There are many solutions to provide MAN services, including SONET, DWDM, CWDM, Ethernet, IP, and ATM. SONET is good for point-to-point connections. CWDM is used for last-mile connections and DWDM is used as the infrastructure for a MAN backbone.
There are different methods of attaching to a MAN: TLS (access link) and DVS (802.1Q trunk). Both have problems with scalability. The service provider can support only 4,096 VLANs for all customers. Q-in-Q (tag stacking) and EoMPLS address this issue. All of these solutions have issues when customer redundancy is implemented, especially when it comes to STP.