Managers are applications or entities that are used to manage Network Elements or Devices. The device can be a router, switch or a PC. The manager can access the data available in the device upon requests and thereby manage the device.
TL1 protocol facilitates communication between a managed device (a device with TL1 agent) and the TL1 Manager or any management application (represents a user of network management).
The TL1 agent on the managed device serves to provide access to data (managed objects) stored on the managed device. The TL1 manager or management application uses this access to monitor and control the managed device.
A TL1 based management network typically consists of three components:
The network device is the network component that needs to be managed. The network device contains a management agent that is software for collecting information and making it available to the NMS.
For each network device to be managed there is a need for an agent that makes the management data on the device available. This agent instruments the management data and makes it available to the TL1 Manager. The agent that makes this data available is a TL1 agent.
The agent and the device are two different things, though the agent runs on the device. The device may not always have an agent, in which case the same information is not available to the NMS.
TL1 Manager (NMS or Management application) typically communicates with one or more TL1 agents available in the network to access the information it needs. Data (TL1 messages) are sent and received in the form of byte stream. These messages allow the TL1 manager to interact with the TL1 agent on the device and thereby manage the device. The extent of management that is possible depends on what the agent makes available. This may be varying from agent to agent.
In addition to retrieving data from the managed resource in response to requests from a management application, agents typically also have the ability to send unsolicited messages to manager applications when they detect some significant event. An unsolicited message of this sort is called trap notification.
TL1 also supports receiving traps or alarms from any TL1 agents. Traps can be classified based on the severity of the message. It can be a Major Alarm, Critical Alarm, Minor Alarm, No Alarm or a Non Alarm. These alarm codes are a part of the TL1 message. Based on the severity of the alarm, users can perform necessary action.