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1.8 Supporting SNMP: Agents

The use of SNMP agents within internetworking devices has increased dramatically in the last few years. There are five general categories of devices in which you’ll find agents: wiring hubs; network servers and their associated operating systems; network interface cards and the associated hosts; internetworking devices, such as bridges and routers; and test equipment, such as network monitors and analyzers. Other devices, such as uninterruptible power supplies, have also become SNMP compatible.

Each of these categories makes a significant contribution to the overall network management scheme. Thus, network administrators who practice proactive network management should seriously consider using network devices that have these imbedded agents. References [1-16] and [1-17] list recent journal articles that detail the widespread acceptance of SNMP.

In conclusion, you can find SNMP agents in almost every internetworking device. Some vendor implementations are better than others. As a result—as the case studies in Chapter 7 demonstrate—not all of these agents are interoperable. You should therefore become as knowledgeable as possible about the details of SNMP. The rest of this book will help with that assignment.

1.9 Desktop Management Task Force

The Desktop Management Task Force (DMTF) was founded in 1992 by Digital Equipment, Hewlett-Packard, IBM, Intel, Microsoft, Novell, SunSoft, and SynOptics Communications (now Bay Networks). The purpose of the DMTF is to develop a standard set of application programming interfaces (APIs) that access and manage desktop systems, components, and related peripherals. At the present time, over 300 organizations are members of the DMTF.

The Desktop Management Interface (DMI) technology is the management architecture developed by the DMTF (see Figure 1-12). The focus of the DMI is on desktop and LAN management, independent of the system, operating system, or network operating system. DMI is designed to be integrated with all network management protocols and consoles, such as SNMP or CMIP.


Figure 1-12.  Desktop Management Interface

The DMI architecture is divided into three layers: the Management Applications Layer, which interfaces with various agents; the Service Layer, which includes the Management Information File (MIF) database; and the Hardware/Software Components Layer, which interfaces with the actual components being managed. Further information on DMTF can be found in references [1-18] and [1-19].

1.10 Web-based Network Management

Network management platforms have evolved in the last few years as client systems have become more distributed and complex. For example, management systems in the late 1980s, often called device managers, were focused on a single device or system, such as a multiplexer or high speed modem network. The first evolutionary progression occurred in the early 1990s as network management platforms attempted to integrate multiple device managers into a cohesive, communicating environment. Further integration became possible when the industry began using SNMP as the communication standard between agents and managers, thus assuring multivendor interoperability between components. Other moves toward integration involved the sharing of database information between various applications so that, for example, an agent’s alarm could automatically trigger a page to the network manager and log an entry in the trouble ticket reporting application.

Yet, all of these improvements have focused on the network management system and its interaction with agents and applications, rather than on the user interface to the network management information.

One of the most common interfaces that has evolved in recent years is the World Wide Web, or simply the Web. Web-based systems consist of a server that stores “pages” of information that are typically formatted using the Hypertext Markup Language, or HTML. The client accesses the information using software called a Web browser, which may have integrated capabilities for printing, file retrieval and storage, email, and so on. The communication protocol between the server and client is the Hypertext Transfer Protocol, or HTTP, which is a transaction-oriented protocol that makes use of the Transmission Control Protocol (TCP). One of the advantages of this architecture is its platform independence, as Web browsers from a number of client platforms, including Macintosh, Windows, UNIX, and other workstations, can access the Web server in a similar manner. Web-based traffic now consumes a large portion of the traffic on the Internet.

The popularity of these Web-based systems has created another application for this technology—storing network management information on a Web server so that it can be accessed and disseminated to distributed users in a platform-independent fashion. Web-based network management can take on one of several forms (see Figure 1-13):

  Web-enabled agents that can be managed through a browser using the HyperText Transfer Protocol (HTTP) for communication.
  Web-enabled managers, which may include a Web server front end to an existing platform, or a stand-alone manager running on a Web server, either of which may use HTTP for communication.


Figure 1-13.  Web-based management architecture

In addition, there are two standardization efforts underway in this area:

  The Web-based Enterprise Management (WBEM) proposal, from a consortium of vendors which include Microsoft, Compaq Computer, Cisco Systems, and many others.
  The Java Management Application Programming Interface (JMAPI) proposal from SunSoft.

In any event, however, SNMP still enters into the equation, either from the perspective of communication with existing (legacy) SNMP agents and/or managers, or the need to provide technical functionality that other solutions do not adequately cover. For example, the HyperText Markup Language (HTML) that is used to define the format of Web pages and is then transmitted with the HyperText Transfer Protocol (HTTP) is not well-suited for manager/agent polling because a requirement exists for the “local human” to push a button to initiate the communication sequence. Manager/agent communication using existing SNMP communication methods are likely to be prevalent until other proposals, such as JMAPI and WEBM, reach maturity. References [1-20] through [1-25] discuss the advantages of Web-based network management.


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