request from the manager to the agent to set the value at a particular instance in the MIB. This is an asynchronous message from the agent to the manager to notify the occurrence of an event. Advantages of SNMP Ease of implementation of agent and manger with few interaction commands Ease of adding program variables to monitor Expandability with minimum effort for future needs due to simple design It is widely implemented and supported by most vendors Simple to setup and use Disadvantages of SNMP Initial version of SNMP had security gaps and SNMP version 2 fixed some security issues regarding privacy of data, authentication, and access control. Information cannot be represented in a detailed and organized manner meet- ing the requirements of next generation network and management due to the simple design. 6.3 Overview of TL1 (Transaction Language 1) The TL1 was developed by Bellcore in 1984 as a man-machine language for network management. The basic intend was to create an open protocol for Fundamentals of EMS, NMS and OSS/BSS managing elements. It consists of a set of ASCII instructions that are human readable. Since TL1 does not require any decoders or debuggers, it has become the preferred CLI (command line interface) for equipment manufacturers. TL1 does not have any message encoding and it does not have an associated infor- mation model. Most of the documentation on TL1 standards was developed by Telcordia. There is a wide range of standard TL1 messages out of which four types com- prise the majority of TL1 communication. They are: Message Explanation Autonomous These are asynchronous messages sent from the messages network element to notify the occurrence of an event. Similar to Trap in SNMP. Input/command These are messages sent from the management messages application to the network element. Output/response These are replies sent by the network element to the messages management application in response to an input/ command message. Acknowledgment These are brief messages from the network element to message