| 摘要 |
A Virtual Path Group (VPG) technique that utilizes network elements (NEs), i .e.,nodes, that are visible to ATM specific defects, and allows for fast ATM virtualconnection/restoration with a minimum of process ing. This is realized by employing a Virtual Path Group transport architecture comprises at least one (1) working route, one (1) protection route, and VPG bridge and selector functions at each end of t he routes. It is applicable to 1+1, mesh and ring protection switching and is extensible t o any virtual connection segment or end-to-end network (cross-subnetwork) virtual connecti ons, and extensible to 1:1 and M:N protection switching. Additionally, the protection switching arrangement of the invention includes an architecture for the Virtual Path G roup (VPG) concept in which the associations among individual ATM virtual channels (VP/ VCs) and VPGs are maintained entirely within the network element management function. This allows VPG support to be added to ATM systems and networks with minimum chan ge from current ATM standards. In particular, no changes are required to the Vi rtual Path Identifier/Virtual Channel Identifier (VPI/VCI) addresses carried within eac h ATM cell across ATM interfaces. Further, defect type indication is realized via a new , for example a F4, segment level Operation and Maintenance (OAM) cell, to initiate the appr opriate restoration action downstream. The technique differentiates between physical layer and ATM layer defects. An algorithm is employed in an embodiment of the inventio n todetermine appropriate VPG protection switch and sign aling actions, driven by the F4 defect type OAM cells. Moreover, for interworking with physical layer protec tion (e.g. SONET Bi-Directional Line Switched Ring (BLSR)), a VPG protection holdoff fu nction is employed at the VPG protection selector. A technical advantage of this pr otection switching invention is that it provides extremely fast protection switching of an extremely large number of ATM virtual connections.
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