Topology discovery and path provisioning in SONET rings using GMPLS

In the light of many mergers and acquisitions in the world of optical transport network, distributed control of SONET/SDH rings using GMPLS has become an important entity. The main requirements are topology discovery, path computation and connection control in the multi-vendor SONET/SDH networks utilizing the in-built protection capabilities of SONET/SDH topologies. In this paper we are explicitly taking up these requirements and making small changes in the OSPF-TE LSA processing rules and RSVP-TE signaling mechanism. To show its application, we take up an example TDM network consisting of 2F BLSR, 1:1 linear, 1+1 linear, unprotected, 4F BLSR and UPSR. We then show how each of the links in the example network is advertised with our changes to enable a remote node or EMS/NMS to discover the topology automatically for each network segment. We also show the creation of path automatically in the same way as the creation of LSP in an MPLS based IP networks. We mention when and where detour LSP setup is required to provide protection and when and how it is taken care by the underlying protection scheme of SONET/SDH