ITU-T Recommendations

The evolution of the existing network in the local area to other switching and transport technologies requires a new concept for the implementation of access networks as a common infrastructure for all types of user accesses to the service nodes. Although there is a strong trend to use optical fibres as the transport medium for an access network, other transmission media shall not be excluded from the access network concept.Access networks shall be capable of supporting existing types of accesses and digital bearer capabilities as well as broadband accesses. The objective of this Recommendation is to describe an access network concept that provides flexibility towards future access types, e.g. for interactive video services.Access networks need to be connected to the service nodes by use of interfaces (Service Node Interfaces) with flexible multiplexing and/or concentration capability. Existing service node interfaces may not be sufficient for upcoming service demands especially not if broadband access types need to be incorporated.