Transaction Language 1

<h2 id="history">History</h2>
<p>TL1 was developed by <a href="/facts/Bellcore/MBQAkk4J">Bellcore</a> in 1984 as a standard man-machine language to manage <a href="/facts/Network_element/f0PtV1UW">network elements</a> for the <a href="/facts/Regional_Bell_Operating_Companies/9azPk76z">Regional Bell Operating Companies</a> (RBOCs). It is based on Z.300 series man machine language standards. TL1 was designed as a standard protocol readable by machines as well as humans to replace the diverse <a href="/facts/ASCII/vGUI33Qu">ASCII</a> based protocols used by different Network Element (NE) vendors. It is extensible to incorporate vendor specific commands.
</p><p>Telcordia OSSs such as NMA (Network Monitoring and Analysis) used TL1 as the element management (<a href="/facts/Element_management_system/VJ0ao3MQ">EMS</a>) protocol. This drove network element vendors to implement TL1 in their devices.
</p>
<h2 id="language-overview">Language overview</h2>
<h3>TL1 Messages</h3>
<p>The TL1 language consists of a set of messages. There are 4 kinds of messages:
</p>
<ol><li><i>Input message</i> - This is the command sent by the user or the OSS.</li>
<li><i>Output/Response message</i> - This is reply sent by the NE(Network Element) in response to an input message.</li>
<li><i>Acknowledgment message</i> - This is an acknowledgment of the receipt of a TL1 input message and is sent if the response message will be delayed by more than 2 seconds.</li>
<li><i>Autonomous message</i> - These are asynchronous messages (usually events or alarms) sent by the NE.</li></ol>
<h3>TL1 message structure</h3>
<p>TL1 messages follow a fixed structure, and all commands must conform to it. However, the commands themselves are extensible and new commands can be added by NE vendors.
</p><p>These are some of the message components:
</p>
<ul><li>Target identifier (TID) & Source identifier (SID) - TID/SID is a unique name assigned to each NE. TID is used to route the message to an NE, SID is used to identify the source of an autonomous message.</li>
<li>Access identifier (AID) - AID identifies an entity within an NE.</li>
<li>Correlation tag (CTAG) & Autonomous correlation tag (ATAG) - CTAG/ATAG are numbers used to correlate messages.</li></ul>
<h4>TL1 input message</h4>
<p>Example:
</p>
<table><tbody><tr><td>ENT-USER-SECU:MyNE:sridev:101::password;</td></tr></tbody></table>
<p>Structure:
</p>
<table><tbody><tr><td colspan="8">TL1 input message</td></tr><tr><td colspan="3">Command code</td><td colspan="4">Staging block</td><td colspan="1">Payload block</td></tr><tr><td>Verb</td><td>modifier1</td><td>modifier2</td><td>TID</td><td>AID</td><td>CTAG</td><td>General block</td><td>Data block</td></tr><tr><td><i>ENT</i></td><td><i>USER</i></td><td><i>SECU</i></td><td><i>MyNE</i></td><td><i>sridev</i></td><td><i>101</i></td><td></td><td><i>password</i></td></tr></tbody></table>
<h4>TL1 output message</h4>
<p>Example:
</p>
<table><tbody><tr><td>MyNE 04-08-14 09:12:04</td></tr><tr><td>M 101 COMPLD</td></tr><tr><td>"UID=sridev:CID=CRAFT,UAP=1:"</td></tr><tr><td>;</td></tr></tbody></table>
<p>Structure:
</p>
<table><tbody><tr><td colspan="8">TL1 output message</td></tr><tr><td colspan="3">Response Header</td><td colspan="3">Response Id</td><td colspan="1">Response block</td><td colspan="1">Terminators</td></tr><tr><td>SID</td><td>Date</td><td>Time</td><td>M</td><td>CTAG</td><td>Completion code</td><td></td><td></td></tr><tr><td><i>MyNE</i></td><td><i>04-08-14</i></td><td><i>09:12:04</i></td><td><i>M</i></td><td><i>101</i></td><td><i>COMPLD</i></td><td><i>"UID=sridev:CID=CRAFT,UAP=1:"</i></td><td><i>;</i></td></tr></tbody></table>
<h4>TL1 acknowledgment message</h4>
<p>Example:
</p>
<table><tbody><tr><td>OK 100</td></tr><tr><td><</td></tr></tbody></table>
<p>Structure:
</p>
<table><tbody><tr><td colspan="3">TL1 acknowledgment message</td></tr><tr><td>Acknowledgment code</td><td>CTAG</td><td>Terminator</td></tr><tr><td><i>OK</i></td><td><i>101</i></td><td><i><</i></td></tr></tbody></table>
<h4>TL1 autonomous message</h4>
<p>Example:
</p>
<table><tbody><tr><td>MyNE 04-08-14 09:12:04</td></tr><tr><td>A  101 REPT EVT SESSION</td></tr><tr><td>"root:NO,"</td></tr><tr><td>;</td></tr></tbody></table>
<p>Structure:
</p>
<table><tbody><tr><td colspan="8">TL1 autonomous message</td></tr><tr><td colspan="3">Auto Header</td><td colspan="3">Auto Id</td><td colspan="1">Auto block</td><td colspan="1">Terminators</td></tr><tr><td>SID</td><td>Date</td><td>Time</td><td>Alarm code</td><td>ATAG</td><td>Verb</td><td></td><td></td></tr><tr><td><i>MyNE</i></td><td><i>04-08-14</i></td><td><i>09:12:04</i></td><td><i>A</i></td><td><i>101</i></td><td><i>REPT EVT SESSION</i></td><td></td><td></td></tr></tbody></table>
<h3>TL1 Surveillance and Maintenance Messages</h3>
<p>TL1 also has application messages for NE and transport surveillance functions. The messages and functions cover a wide variety of NE types, user needs, and supplier innovations.
</p><p>Telcordia 
<a href="http://telecom-info.njdepot.ericsson.net/site-cgi/ido/docs.cgi?ID=SEARCH&DOCUMENT=GR-833&">GR-833, TL1 Surveillance and Maintenance Messages</a> contains the generic functions and messages that pertain to the following generic types of NEs:
</p>
<ul><li>Digital Loop Carrier (DLC)
<ul><li>Central Office Terminal (COT)</li>
<li>Integrated Digital Loop Carrier (IDLC)</li>
<li>Remote Digital Terminal (RDT).</li></ul></li>
<li>Digital Terminal and Cross-Connect Equipment
<ul><li>Automated Digital Terminal System (ADTS)</li>
<li>Digital Cross-Connect System (DCS)</li>
<li>Hybrid Add/Drop Multiplexer/Digital Cross-Connect System (ADM/DCS)</li>
<li>Optical Add/Drop Multiplexer (OADM)</li>
<li>Reconfigurable Optical Add/Drop Multiplexer (ROADM)</li>
<li>Low Bit-Rate Voice (LBRV) Terminal.</li></ul></li>
<li>Digital Multiplexing and Line Terminating Equipment
<ul><li>Multiplexer (MUX)</li>
<li>Add/Drop Multiplexer (ADM)</li>
<li>Line Terminating Equipment (LTE)</li>
<li>Repeater (REP)</li>
<li>Automatic Protection Switching (APS) Equipment.</li></ul></li>
<li>Digital Switching Systems
<ul><li>Circuit Switching (CS) System</li>
<li>Packet Switching (PS) System (including Access Concentrators).</li></ul></li>
<li>ISDN Switching Systems</li>
<li>SONET Transport Systems</li>
<li>FITL Transport Systems
<ul><li>Passive Optical Network (PON).</li></ul></li>
<li>Metro Ethernet Systems</li>
<li>Common Channel Signaling (CCS) Systems
<ul><li>Signal Transfer Point (STP)</li>
<li>Service Control Point (SCP)</li>
<li>Service Switching Point (SSP).</li></ul></li>
<li>Supervisory Systems (SSs)</li>
<li>Environment Monitors (EMs)</li>
<li>Timing Signal Generator (TSG)</li></ul>
<p>An NE address consists of two types of parameters, routing and access. The maintenance functions can be grouped into the following six categories:
</p>
<ul><li>Alarm Surveillance (AS) − Messages of events or conditions (e.g., carrier group alarms, threshold violations).</li>
<li>Performance Monitoring (PM) − Generated performance data (e.g., number of errored seconds, number of slips).</li>
<li>Failure Identification (FI) − Mechanisms within the NE to detect and isolate equipment and facility troubles.</li>
<li>Recovery and Control (RC) − Maintenance purposes. This includes Maintenance State Control, Loopbacks, External Device Control, Initialization, Emergency Reconfiguration, and Process Inhibit and Termination.</li>
<li>Maintenance Measurement (MM) − to be used for overall assessment of the NE maintenance process.</li>
<li>Memory Backup (MB) − To/from non-volatile memory within the NE.</li></ul>
<p>GR-833 provides detailed descriptions of commands and responses in the TL1 format.
</p>
<h2 id="external-links">External links</h2>
<ul><li><a href="http://noc.surfsara.nl/nrg/TL1-Toolkit/">TL1 Toolkit, an Open Source Perl module for TL1</a></li>
<li><a href="http://telecom-info.njdepot.ericsson.net/site-cgi/ido/docs.cgi?ID=SEARCH&DOCUMENT=GR-831&">Telcordia GR-831-CORE - OTGR Section 12.1: Operations Application Messages - Language for Operations Application Messages</a></li></ul>

Transaction Language 1 open-in-new

Transaction Language 1