Service breadth where the providers must be able to offer a variety of offerings like IP, Frame Relay, Ethernet, ATM etc. with flexibility for new services without heavy additional cost. Service delivery where the network is optimized for changing access requirements with easy and quick provisioning.

Service awareness where requirements as QoS, class of service, protection levels take higher precedence. Scalability where the network capacity should be able to scale much higher than the capital costs for upgrades.

Network reliability where the capability of a SONET network must be maintained with regard to protection and restoration. Co-existence with existing infrastructure to carry voice as well as data traffic as well as interfacing with existing infrastructure.

Topological flexibility where the equipment must be able to support different physical topologies thereby supporting flexible application traffic flows.

Reduction in operational and network costs since the metro network is driven by central office access and transmission equipment costs. Newer equipment must offer increased functionality and performance without proportional cost increase.

(Source: Wipro)