TCP/IP network management is based on the Simple Network Management Protocol, abbreviated SNMP. As we saw in the overview topic, however, this term is ambiguous. While it is commonly used to refer to the actual communication protocol used to exchange network management information, the term also refers to the entire set of technologies that enable TCP/IP network management. The technical name for this larger architecture is the Internet Standard Management Framework. Again, even though it may seem strange, this term is actually abbreviated in the standards as “SNMP”. For simplicity, I abbreviate it as the “SNMP Framework”, to differentiate it from the SNMP protocol.

he Internet Standard Management Framework encompasses all of the technologies that comprise the TCP/IP network management solution. The SNMP Framework consists of a number of architectural components that define how management information is structured, how it is stored, and how it is exchanged using the SNMP protocol. The Framework also describes how the different components fit together, how SNMP is to be implemented in network devices, and how the devices interact.

As we will explore in more detail later, the Internet Standard Management Framework is entirely information-oriented. It includes the following primary components (see Figure 271):

• Structure of Management Information (SMI): To ensure interoperability of various devices, we want to have a consistent way of describing the characteristics of devices to be managed using SNMP. In computer science, a data description language (DDL) is the tool for this job. The Structure of Management Information (SMI) is a standard that defines the structure, syntax and characteristics of management information in SNMP.
  
  
• Management Information Bases (MIBs): Each managed device contains a set of variables that is used to manage it. These variables represent information about the operation of the device that is sent to a network management station, and/or parameters sent to the managed device to control it. The management information base (MIB) is the full set of these variables that describe the management characteristics of a particular type of device.
  
  Each variable in a MIB is called a MIB object, and is defined using the SMI data description language. A device may have many objects, corresponding to the different hardware and software elements it contains. Initially, a single document defined the MIB for SNMP, but this model was inflexible. To allow new MIB objects to be more easily defined, groups of related MIB objects are now defined in separate RFC standards called MIB modules. Over 100 such MIB modules have been defined so far.
  
  
• Simple Network Management Protocol (SNMP): This is the actual SNMP protocol itself. It defines how information is exchanged between SNMP agents and network management stations. The SNMP protocol operations define the various SNMP messages and how they are created and used. SNMP transport mappings describe how SNMP can be used over various underlying internetworks, such as TCP/IP, IPX and others.
  
  
• Security and Administration: To the three main architectural components above, the SNMP Framework adds a number of supporting elements. These provide enhancements to the operation of the SNMP protocol for security, and address issues related to SNMP implementation, version transition and other administrative issues.
  

  Figure 271: Components of the TCP/IP Internet Standard Management Framework