| 摘要 |
<p>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 virtual connection/restoration with a minimum of processing. 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 the routes. It is applicable to 1+1, mesh and ring protection switching and is extensible to any virtual connection segment or end-to-end network (cross-subnetwork) virtual connections, 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 Group (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 change from current ATM standards. In particular, no changes are required to the Virtual Path Identifier/Virtual Channel Identifier (VPI/VCI) addresses carried within each 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 appropriate restoration action downstream. The technique differentiates between physical layer and ATM layer defects. An algorithm is employed in an embodiment of the invention to determine appropriate VPG protection switch and signaling actions, driven by the F4 defect type OAM cells. Moreover, for interworking with physical layer protection (e.g. SONET Bi-Directional Line Switched Ring (BLSR)), a VPG protection holdoff function is employed at the VPG protection selector. A technical advantage of this protection switching invention is that it provides extremely fast protection switching of an extremely large number of ATM virtual connections. <IMAGE></p> |
