During the mid 80s, Bellcore embarked on specifying a standard man-machine language to manage network elements (NEs.) It was to be based on Z.300 series Man Machine Language (MML) standards. It was designated Transaction Language 1 or simply TL1.
This effort encompassed specifying a language as well as message set(s) for managing a variety of Telecom equipment from different domains. TL1 made its foray into carrier networks well over a decade ago and during the subsequent years, TL1 deployments became widespread in the RBOC space. Today TL1 is a widely used management protocol in the SONET and access infrastructure in North America. Popular Telcordia (Formerly Bellcore) OSSs (Operations Support System) such as NMA (Network Monitoring and Analysis) use TL1 as the element management protocol.
TL1 is human decipherable protocol that can be easily guised as a machine-to-machine language. It is a multi-vendor and multi-technology protocol with comprehensive management support. Processes for design and implementation of TL1 interfaces are well established and are relatively straightforward. Since TL1 is human readable, special decoders or debuggers are not necessary and has become the preferred CLI (command line interface) for NE vendors. Finally, TL1 can support next generation network elements and the ever-increasing scalability and extensibility needs.
