Network management

The roots of the network management protocols that are in common use today can be traced back to developments in the late 1980s. Prior to that time, network management had typically been performed using low-level signaling techniques to send special control information. Receipt of this information would cause receiving hardware to cease normal operation and enter a special diagnostic mode in which it responded to commands contained in the information. This approach worked well in homogeneous networks, which used the same interface technology throughout. However, with the advent of protocol stacks and abstraction of the lower level network characteristics, networks began to support multiple different types of interface technology, which meant that a different approach was necessary in order to support network-wide management. At this point, both the TCP/IP and Open System Interconnect (OSI) protocol stacks began to define network management protocols that operated at the application layer. This change in approach had both advantages and disadvantages. The major advantage was that management could now be performed using the same tools at any point in the network; the major disadvantage was that management was only possible when the entire protocol stack was active and working correctly. The move to an application-layer approach caused the creation of a client/server architecture that is still in widespread use. A management client that executed under the user account of the network administrator on a host computer communicated with management servers resident on each of the other items of equipment in the network that required management. In early networks, the servers tended to reside on only two types of “other equipment” hosts, an...

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...rity model and view-based access control, was completed in 1999 but has not yet gone beyond Draft Standard status at the IETF.

The history described above, therefore, is one of incremental extension and clarification since the move to application-level management in the late 1980s. The “data model” has remained largely unchanged in that time, and still consists of independently specified variables collected into groups for ease of access only. Relationships and dependencies between the variables are still expressed only in the text of descriptions, and therefore cannot be analyzed or checked by tools such as compilers. Although this approach is eminently suitable for the job for which it was first envisaged, namely the collection of statistics from gateways, it has distinct limitations with respect to the overall management of today’s dynamically changing networks.