ABSTRACT: Automated Protection Switching (APS) improves the survivability of transport systems by substituting a standby facility when failures occur. For failures that affect not only the working channels but also the protection channels, such as a cable cut, one type of protection is a Ring APS. A ring is defined as a set of nodes interconnected to form a closed loop, where fiber cables serve as links; thus the Network Elements (NEs) are connected in a ring configuration. A node refers to Synchronous Optical Network (SONET) Line Terminating Equipment (LTE).

There are two major types of SONET rings: path-switched and line-switched SONET rings. GR-1230-CORE, Issue 4 provides the view of Telcordia on proposed generic criteria for two-and four-fiber Bidirectional Line-Switched Rings (BLSRs). Criteria for BLSR equipment, BLSR basic APS protocol, ring interconnection, and OAM&P are provided, including criteria for enhancements to the basic BLSR APS protocol such as extra traffic, VT-access, and support for unidirectional services.

In addition, criteria for Dual Transmit and Enhanced Non-pre-emptible Unprotected Traffic is included. This GR also provides tutorial material.

GR-1230 replaced TA-NWT-001230.

This GR also includes one or more Issue List Reports (ILRs) that details open or closed technical issues in the main document. The ILR(s) are automatically sent free of charge to the GR document purchaser.