PMR or satellite. The network can be analogue or digital and it can carry a mix of services. PLATFORM Within this range of networks there exists an equally wide spread of equipment needing management. Modern devices often conform to some standardised interface, and have on-board intelligence Figure 16.2 Simplified representation of the elements of which allows sophisticated management functions. Older equip- network management ment have interfaces which do not conform to any standards, and are therefore very difficult to manage as part of an integrated This not only consists of the hardware, such as a workstation or network. Furthermore, with liberalisation growing throughout the mainframe computer, but also any associated platform related soft- world, users are free to shop around for the most economical ware, such as the operating system and commercially obtained equipment to meet their needs. The networks will therefore contain database. a mix from many suppliers, and all of these need to be managed as Above this platform sits the interfaces to the elements outside the one unit. manager. This may consist of the elements being managed, such as NETWORK OWNER TRANSMISSION MEDIA NETWORK TYPE SERVICE CARRIED VIDEO RADIO VIRTUAL PRIVATE NETWORK Figure 16.1 The hierarchical structure of a network 16/4 Network management a modem, multiplexer, or cross connect, or it may be another location, usually by a large mainframe computer. Although suitable manager within a management hierarchy, as described in the next for small networks, spread over a limited geographical area, this section. These interfaces have traditionally been proprietary to the solution becomes difficult to operate where information has to be vendors who supplied the equipment, but more and more they are transported over long distances. Wide area bandwidth is expensive conforming to standards, such as OSI or SNMP, as described in the and the management information carried over the links competes for following sections. Above the hierarchy is the final 'l