Shortly after that magical, wondrous moment when the first two computers were connected together and a message was transmitted or a file was exchanged, the network went down.
At that moment, network and system management was born.
Prior to that climactic moment, most computer-engineering efforts were geared toward getting individual computers to work. Debugging a single computer itself is no small feat, involving significant effort just to determine the area causing the problem. If it's hardware, which component? Memory, disk, peripherals, CPU or some connection between them could be at fault. If software, which piece? The operating system, the application program, the memory manager or a connection between them could be the culprit. Anyone who has spent time on the phone with tech-support sorting out a problem with a single personal computer knows that many factors can be involved.
As soon as you network computers, the number of possible problems multiplies. In most networks, more than one vendor and many technologies are involved. To the possible hardware problems associated with one computer, add problems with cabling, routers, hubs and network cards. To the usual list of software suspects associated with one computer, add network operating systems, network card drivers and router software. The scene can become quite confusing, flush with vendor finger-pointing.
In the late 1980s, as networks and network management were developing into a major problem, several standards initiatives emerged to help vendors and users tackle their mounting problems. Some of the terminology involved can be confusing, but to be successful, it is important for IT managers to be familiar with some of the basic concepts and terms often mentioned in connection with network and system management.
Network vs. System Management
Obviously, a network consists of both the communication channels and the devices using those channels. The communication channels consist of the wires, protocols, software and devices providing the medium through which machines talk to one another. The devices using the network are everything else that lives on the network -- workstations, printers and scanners.
The handling of the network, including things like routers and hubs, is called network management. Management of the devices using the network, such as workstations, is called systems management. In recent years, however, the distinction between the two has become blurry as tools have emerged that give a unified view of both network and systems management.
SNMP, CMIP and MIBs
Two common protocols to manage Internet devices emerged at approximately the same time: the Simple Network Management Protocol (SNMP) and Common Management Information Protocol (CMIP). Originally, SNMP was intended to fill the short-term need for network management, to be eventually replaced with CMIP for long-term needs. As its name implies, SNMP is a simple protocol -- its original description was only 32 pages -- that was easy to implement. It provides a simple query-type protocol that a network management program uses to ask devices living on the network how they are doing, how busy they are, what errors they have encountered, etc.
When SNMP was published, so was a list of information it could request from various kinds of devices. This list is called a Management Information Base (MIB). The original MIB contains a hierarchical list of objects, starting from the largest and descending to the smallest. The Internet itself is one of those objects -- at some level underneath it are individual devices such as routers, hubs, switches, etc. The MIB lists all the essential variables a particular type of object should make available to a network-management program. For example, the MIB contains a list of the variables routers should maintain and make available. The MIB describes what is available, SNMP tells how to get it.
Because network-management programs know the MIB, they know which variables they can get from which kinds