7.2 Management Schemes

The large number of management schemes grew out of the history and involvement of multiple standards organizations.

CMIP was specified by the ITU-T for managing networks. It is a machine-to-machine protocol, like SNMP, with a manager–agent paradigm. The Transaction Language 1 (TL1) method of configuration was specified by Bellcore (now Telcordia) as a Man Machine Language (MML) for controlling network elements. It is both a CLI and a protocol, and the PDUs are humanly readable. The most significant reason for its success was that performance reporting and alarms were very well specified. Even though the SONET standard recommends CMIP as the management interface, SONET network elements introduced in the late 1980s had TL1 interfaces. In fact, many of the companies building next-generation SONET equipment in the late 1990s had to support TL1 since that was the only interface the network operators were familiar with.

SNMP was specified by the IETF, which was seen as the key standards body for data networking. Many of the routers and switches first implemented a CLI and an SNMP agent. Though CMIP could have been used instead of SNMP for managing these devices, it never really caught on in the data networking world.

Command Line Interfaces were required for the power users. While some people have likened this to using the DOS prompt when we have the option of a Graphical User Interface (GUI), this mode of configuration survives and continues to thrive. Similar to the TL1 requirement, many of the companies building data networking devices are shipping their products with a familiar CLI interface. The CLI can be accessed via a serial port on the device or via a telnet interface.

Common Object Request Broker Architecture (CORBA) was specified by the Object Management Group (OMG) and is quite popular in enterprise systems. The architecture is similar to a remote procedure invocation between a client and server, with the broker acting as a message passing mechanism. The model was successful because it is programming language independent and uses an object-based approach to data invocation and interchange.

Telecom service providers found CORBA to be a useful way to manage network elements, especially when the elements need to be tied into their own service management and billing systems that are CORBA based. There are some efforts underway to provide translation between TL1 and CORBA for interfacing to legacy systems.

HTTP-based management is often used instead of telnet-based CLI for configuration and control. With HTTP, we have the familiar interface of a Web browser and a less cumbersome way to configure parameters. A pulldown menu can contain only the valid values for a variable, thus removing the possibility of user error, since no other value can be provided as input.

Extensible Markup Language (XML) is used as another scheme for managing communications devices. XML permits a machine independent way of data interchange across machines. XML translator software on the peer systems interpret the XML data according to the context. The model is similar to CORBA-based management but with XML traffic sent over an HTTP connection.