TL1

    *Transaction Language 1 (TL1) is a set of ASCII-based instructions, or "messages," that an operations support system (OSS) uses to manage a network element (NE) and its resources. TL1 is the dominant management protocol for controlling telecommunications networks in North America today and remains the only widely-implemented, vendor-independent telecommunications management protocol. NE vendors work with TL1 to implement embedded management interfaces for their NEs, while service providers have large TL1-based management OSSs that control those NEs. TL1 is deployed in existing equipment, as well as in new technology equipment such as xDSL and WDM.

    *2. History of TL1 Before TL1, each NE vendor typically implemented that vendor's own type of ASCII-based control language. Each language was different, so each had to be separately memorized by operators and programmed by developers of OSSs and NEs. Bellcore, in its role as standard setter for the Regional Bell Operating Companies (RBOCs), decided in 1984 to specify a standard man machine language (MML) for controlling network elements. The language was named Transaction Language 1 (TL1). The following year, the first large-scale OSSs, like NMA from Bellcore, were delivered. They needed NEs to support TL1 interfaces. Because RBOC OSSs required TL1, NE vendors rapidly implemented it, particularly in the transport and access areas.


    *

      3. TL1's advantages as a management protocol
    *

      Standard Command-line Interface - TL1 provides an industry standard command line interface CLI for managing network elements. It is also flexible enough to allow for vendor extensions where appropriate.
    *

      Tracking of Alarms/Events - TL1 supports two basic types of TL1 messages: commands sent from an OSS, and events sent from an NE.
    *

      Human-to-machine Language - TL1 messages are in plain ASCII text, so operators and developers alike can always read them. As messages are easily readable, TL1 does not require sophisticated debuggers or protocol analyzers - what you see is what you get.
    *

      Machine-to-machine Language - A TL1 message dialogue can easily provide a communications stream equivalent to a binary encoded stream. Unlike the binary encoded stream however, humans are also able to read the messages. This provides a unique fall back that no other protocol provides - the human operator.
    *

      Small Footprint - Unlike alternative approaches, TL1 has a small footprint that allows it to co-reside with other management protocols and makes it easy to embed on both new and existing network equipment.
    *

      Services - Unlike protocols such as SNMP, TL1 has a well-defined set of management services for performance, fault, security and other areas of management. For instance, an operator has standard ways to set up performance schedules and receive performance reports from any vendor's TL1-manageable NE.
    *

      Tracking of Alarms/Events - TL1 easily tracks and handles events with a built-in identifier, or "alarm correlation tag" called an ATAG. This unique identifier TL1 is inserted in each autonomous alarm or event message sent from an NE. If an alarm message is "lost," the manager knows about it, as the ATAG of the next event is not in order.


    *

      4. TL1 as a CLI Most network elements come with Command Line Interfaces (CLI). These interfaces, accessible via telnet or over a serial line, allow human operators to type in ASCII commands to query and control the network element. In many cases, complex provisioning is only supported through the equipment's CLI. Initial "turn up" of equipment is invariably performed through the CLI. Many CLIs support "help" and other feedback facilities to aid the user.
          o In telecommunications, TL1 is the most popular CLI. Because it's ASCII, human operators can compose it and directly interpret responses and events. Unlike many other CLIs, TL1 is not free-form, with the syntax of one command differing from the next. As a result, element managers use the same TL1 interface.
          o In the enterprise world, traditionally each equipment vendor for equipment such as routers have defined their own CLI. These vendors usually provide SNMP interfaces, at least for monitoring their equipment, and element managers that bypass the CLI and use the non-human readable, formally defined interfaces. However, complex provisioning is still performed using a CLI in a telnet session.
      For speed of provisioning and querying, nothing beats the CLI command composed by practiced fingers. Other management interfaces are retrofitted after the element has been made and rarely cover the range of function available in the incrementally enhanced CLI. TL1 is the only standard, cross-vendor CLI and has been used in telecommunications for over 15 years. It is well documented and has a well-defined syntax and so may be used by both man and machine: many telco element management systems like Bellcore/Telcordia's NMA are built to use TL1. And now with Lumos' TL1 Agent, it is the only CLI with product support.


    *

      5. TL1 compared to SNMP Both SNMP and TL1 share the following benefits:
          o Widespread implementation
          o Ease-of-use and ease of implementation
          o Can co-reside with each other or with other management protocols
          o Follow a client/server or manager/agent paradigm
          o Standards-based protocol
      SNMP: leading protocol for enterprise networks SNMP was adopted in 1989 as the standard basic management service for networks that operate in TCP/IP environments.
          o Just as TCP/IP is the dominant communications protocol, SNMP is by far the most dominant network management protocol in IP networks.
          o Virtually all enterprise networks and many public networks include SNMP NEs and OSSs.
          o SNMP provides solid approaches to NE identity, discovery, and security (V3)
          o SNMP provides a machine-readable interface definition.


    *

      TL1: leading protocol for public networks Transaction Language One (TL1) remains the only widely implemented, vendor-independent public telecommunications management protocol in existence. Before TL1, each NE vendor typically had its own ASCII-based control language. Each had to be learned and programmed separately. In 1984, Bellcore, the standard setter for Regional Bell Operating Companies (RBOCs), specified TL1 as a standard man machine language (MML) for controlling NEs.
          o Widely implemented by telco service providers and equipment manufacturers, particularly in the transport and access arenas.
          o Small footprint that allows it to co-reside with other management protocols and makes it easy to embed on both new and existing network equipment
          o TL1 has a well-defined set of management services for performance, fault, security and other areas of management.
          o It is inherently a command line interface (CLI).
          o Flexible transport


    *

      6. OSMINE Certification

      NE Vendors marketing their products to Service Providers must factor Telcordia's network integration process, known as OSMINE (Operations Systems Modification of Intelligent Network Elements) into their development plans. OSMINE is the process by which network equipment is certified to be compatible and interoperable with Telcordia Operations Support Systems (OSSs). Telcordia claims to have created 80% of the OSSs used by the RBOCs, and many Service Providers mandate that their equipment be OSMINE certified. For further information on the OSMINE process, visit www.telcordia.com


    *

      7. Telcordia (Bellcore) TL1 standards

      Here's a list of Telcordia/Bellcore standards documents. You can order these documents from Telcordia's website store

      Specification or Doc. Number
     

      Title
     

      Description

      TR-NWT-000831
     

      Operations Application Messages - Language for Operations Application Messages.
     

      Defines the basic TL1 command structure, including the basic syntax and form of a TL1 message. All TL1 messages should conform to this standard. This is the "beginning" specification for learning all about TL1 syntax.

      GR-199-CORE
     

      OTGR: Operations Application Messages - Memory Administration Messages
     

      Otherwise known as provisioning messages.

      GR-833-CORE
     

      Network Maintenance: Network Element and Transport Surveillance Messages
     

      Describes TL1 messages that are otherwise known as alarm and data collection messages.

      SR-NWT-002723
     

      Applicable TL1 Messages for SONET Network Elements
     

      This document provides lists of messages that Telcordia/Bellcore recommends for supporting SONET NEs.

      SR-1665
     

      NMA Operations System - Generic Transport Network Element Interface Support
     

      This document lists the TL1 commands, responses, and autonomous messages supported for the generic interface between the proprietary NMA OS and NEs.

      GR-1093-CORE
     

      Generic State Requirements for Network Elements
     

      Presents generic state requirements for NEs, including a comparison of the Telcordia/Bellcore State Model and the ISO State Model. This specification does not define any particular messages; instead, it defines state parameters that may be used in TL1 messages.

      TR-NWT-00835
     

      OTGR: Operations Application Messages - Network Element and Network System Security Administration Messages
     

      Describes the messages and data related to NE and system security.

      GR-202
     

      Loop Testing Messages at the OS/TSC Interface
     

      Presents requirements for TL1 messages to accomplish the testing of customer loops (Plain Old Telephone Service or POTS) over the Operations System/Test System Controller-Remote Test Unit (OS/TSC-RTU) interface.

      GR-811
     

      OTGR: Operations Applications Messages - TL1 Messages Index
     

      This document is organized into tables that provide listings of the TL1 Operations System-Network Element (OS-NE) Command Messages and TL1 Network Element-Operations System (NE-OS) Automatic Messages.

      GR-834
     

      Network Maintenance: Access and Testing Messages
     

      Describes TL1 messages for executing access and testing functions.