Section IX: Network and Systems Management

Network Management

Although the physical location of the personal computers on a local area network seldom changes, networks are still dynamic entities. That is, the logical makeup of any network fluctuates from moment to moment.

For example, the number of data and application files in use or stored away, the amount of available disk storage space, the number of users logged in to the network, and the volume of traffic passing through the network cabling all change continually. Moreover, a network offers users a distributed-processing environment, with some processing performed by a centrally located server, some done at users' workstations, adding even more activity to the network.

Keeping this conglomeration of network hardware, software, cables, and the people using them working efficiently comes under the ambiguous term of network management. It's ambiguous in that managing a network can range from the simple to the complex, from a moment's quick fix of plugging in a misplaced network cable to a day-long search for an obscure disk problem.

Network management can be as simple as creating a boot diskette for a new user and making sure that user has proper access to network resources. (Although in truth these jobs may not be all that simple in some widely distributed networks.)

Or managing a network can include daily disk-maintenance duties backing up network files or defragmenting disk directories. Or it may mean troubleshooting the network, trying to discover why some users are experiencing slow network response. Or it may include reconfiguring a remote internetwork device to improve overall system performance.

In short, network management incorporates an almost unlimited list of dutiesbasically, doing whatever it takes to keep the network running smoothing and efficiently, with minimal or no downtime.

This job has grown even more difficult as networks have become larger and more complex. The evolution from small workgroups of often identical PCs to large internetworks made up of dissimilar machinesIBM PS/2s, Macintoshes, PC clones , printers, communications gateways, and bridges and routershas brought more power to the desktop while adding immense complexity to the network manager's job.

Fortunately, vendors are developing more and better toolssome software-based, others complete systems that provide onscreen maps of network resourcesto help in the endless task of managing a network.

From Simple To Complex

Network management tools, whether they are as application-specific as a performance monitor or as comprehensive as IBM's mainframe-based NetView, help bring some order to the potentially chaotic network management environment. They give network managers information and capabilities they can use in the battle to keep their networks running trouble-free.

Whether they are intended to merely find cable breaks or to pinpoint the cause of a network slowdown , network management tools are vital to the network manager's day-to-day life. They can help ensure uptime and network reliability, maintain predetermined performance levels, manage network resources optimally, plan for expansion, maintain company security, track network use, and provide a basis for charging customers for network time.

For example, knowing how many network users regularly access a laser printerand how long they have to wait for their printed material to appear can help a company decide when it's time to add a second printer. Knowing which workstations generate the heaviest traffic lets a network administrator predict possible bottlenecksbottlenecks that can be avoided by adding internetwork devices such as bridges or routers.

Five Functional Areas

At a basic level, network management requirements generally fall into five functional areas: configuration management, fault management, security management, performance management, and accounting management.

Configuration management applications deal with installing, initializing, booting, modifying, and tracking the configuration parameters or options of network hardware and software.

Fault management tools provide an audit trail, or historical overview, of a network's error and alarm characteristics. These types of tools show a network manager the number, types, times, and locations of network errors. These errors might be dropped packets and retransmissions (on an Ethernet) or lost tokens (on a Token Ring).

Security management tools allow the network manager to restrict access to various resources, from the applications and files to the entire network itself; these generally offer password-protection schemes that give users different levels of access to different resources. For instance, a user in marketing could be allowed to view, or read a data file in accounting but not be permitted to change or write to it.

Security management is also important in managing the network itselffor instance, only certain individuals (such as network administrators) should be permitted to change configuration settings on a server or other key network devices.

Performance management tools produce real-time and historical statistical information about the network's operation: how many packets are being transmitted at any given moment, the number of users logged into a specific server, and utilization of internetwork lines. As already noted, this type of information can help network administrators pinpoint areas or network segments that pose potential problems.

Performance management tools generally allow polling individual network devices for component-specific information. A communications server might provide information on throughput for each serial port, while a file server might report the number of users logged in, what applications they are using, and the number of active files. This information can then be studied to determine which gateways, servers, or routers are being used heavily and may need added capabilities in the future.

Accounting management applications help their users allocate the costs of various network resourcesa public data network gateway, access to a mainframe session, or printer timeto those using them. These applications provide information about session start up/stop, user logins and resource use, and audit trail data. Companies can then use this information to bill departments internally or customers for computer and/or network time.

Built-In NOS Management

Most network operating systems (NOSs) provide some level of network management capabilities; in particular, almost all the leading NOSs offer password-protection schemes that limit users' access to network resources. Novell, for instance, implements its NetWare management scheme through user profiles, which define not only the user's access rights, but the users' classifications (supervisor, workgroup manager, console operator, or user), which also determine the resources they can access.

In this scheme, a supervisor has access rights that allow reconfiguring and upgrading the entire system. The workgroup manager, available with NetWare 3.X, controls only the resources of a single user or user group . This concept allows a supervisor to distribute some of the responsibility for maintaining the network to others around a large network.

A user with console operator access rights can run NetWare's FCONSOLE utility, which allows monitoring and controlling a variety of network performance criteria, such as print queues. The user can access only those resources allowed by the supervisor (or workgroup manager with NetWare 3.X). Although users can access the NetWare management utilities, their rights to actually perform management functions are severely limited.

Although other NOSs' access schemes may differ in specific features from NetWare's, they all offer similar resource-restriction capabilities that give the network managers control over their networks.

Programmable Managers

Many other network product vendors also offer specific network management products that address more-detailed needs. These include Sun Microsystems's SunNet Manager [now known as Solstice], Hewlett-Packard's OpenView, IBM's NetView for AIX, and Cabletron's Spectrum.

Both Sun and Hewlett-Packard designed their network management applications to work with other vendors' "agent" applications that add specific functionality to a system. For example, various agents can perform monitoring and controlling capabilities on gateways and routers.

Other products, however, deliver only partial solutions. These devices include protocol analyzers, which provide configuration and performance data but no accounting management capabilities.

Management Standards

As networks have grown larger and become increasingly heterogeneous in nature, so has the need for industry-standard network management protocols (and products) that operate across a wide range of vendor offerings. The first of these protocols, the Simple Network Management Protocol (SNMP), was developed by the Internet Activities Board in 1988. SNMP generally relies on the User Datagram Protocol/Internet Protocol (UDP/IP) as the underlying mechanism for transferring data between different types of systems and networks, though IPX and AppleTalk have been employed successfully by some products.

Briefly, SNMP is a protocol that defines the communication between a network management station and a device or process to be managed. SNMP's three-layer architecture (network management stations , agents, and a common set of protocols that binds them together) operates with a management information base (MIB) and a structure of management information (SMI). The MIB and SMI are network management concepts that allow defining each network element so these elements can be monitored and controlled by the management stations.

Though widely accepted, SNMP has several limitations. For one, it is considered by some to be too simplistic for managing the large, global-style networks evolving today, and its manager-to-agent architecture leaves it incapable of managing true enterprise-wide networks, which can require manager-to-manager systems as well. Because products based on it are widely availablehundreds of vendors make compatible productsSNMP remains the network management protocol of choice for most PC-based network managers.

Host-Based Systems

Two mainframe-based network management systems with wide industry support are IBM's NetView and AT&T's Unified Network Management Architecture (UNMA.)

Although proprietary in nature, these products enjoy broad end-user support because of their associated vendors' large installed bases of computers. With the protocols already available, many users incorporate their primary vendor's network management products into their networks as a matter of course. IBM's NetView permits nonIBM networks to access the NetView host via its NetView/PC and LAN Network Manager gateway products. IBM also supports SNMP in many of its products.

This tutorial, number 26, by Jim Carr, was originally published in the September 1990 issue of LAN Magazine/Network Magazine.