ABSTRACT: Issue 3 of GR-1400, SONET Unidirectional Path-Switched Ring (UPSR) Equipment Generic Criteria, replaces Issue 2.

GR-1400 contains the Telcordia view of generic criteria for Network Elements that are specified to be capable of being deployed as nodes in Unidirectional Path-Switched Rings (i.e., UPSR NEs). UPSR NEs utilize one of the Automatic Protection Switching (APS) schemes that have been defined to improve the survivability of transport systems by allowing them to switch to standby equipment or facilities to process or carry network traffic when degradations affecting the active equipment or facilities occur.

Issue 3 contains the following additions and changes:

• A significant reorganization has been done, and the scope of the document has been expanded to include other NEs [in addition to SONET Add-Drop Multiplexers (ADMs)] that may be deployed as nodes in a UPSR [e.g., SONET Digital Cross-Connect Systems (DCSs)]
• Various requirements have been updated to align with the latest issue of GR-253-CORE, Synchronous Optical Network (SONET) Transport Systems: Common Generic Criteria
• New sections have been added to address new developments in the technology
• Various existing criteria (and in most cases, explanatory text) have been revised and new criteria added on the path selection process, provisioning, switch initiation times, switch completion times, and other issues
• New or modified explanatory text has been provided on a number of topics, including the functional architecture of a UPSR, the various applications in which a UPSR NE might be deployed, and the operations communications routing and interworking functions that a UPSR NE may need to support.