Generalized MPLS-based distributed control architecture for automatically switched transport networks

Current circuit-switched transport networks, such as plesiochronous digital hierarchy (PDH) and synchronous optical network/synchronous digital hierar chy (SONET/SDH) have traditionally used centralized network management for connection control. To facilitate the value-added capabilities of today's n etworks-such as the rapid provisioning of services, dynamic setup of bandwi dth requests, and fast mesh-based restoration-distributed connection contro l using signaling protocols has quickly gained industry momentum. Efforts h ave been initiated in various standards bodies to define the automatically switched transport network (ASTN). Although many architectural choices are now available, this paper describes a distributed control plane architectur e that can be applied to various circuit-switching technologies and differe nt network applications. This architecture adopts the concept of a generali zed version of multiprotocol label switching (MPLS) which extends and modif ies MPLS and other protocols on the Internet to make them applicable to var ious transport networks and also facilitates optical data networking. Four major functional components are incorporated in this architecture: element- level resource discovery, state information dissemination, path selection, and path control modules. Using these concepts, the transport network can b e viewed as a virtual nonblocking, reconfigurable backplane of different ne twork clients. This view represents a radical departure from the traditiona l data networking view of transport networks as providing fixed pipes and w ill have a dramatic impact on future network interworking and end-to-end tr affic engineering (TE).