The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Network Configuration and Management Protocols (BOOTP, DHCP, SNMP and RMON)            9  TCP/IP Network Management Framework and Protocols (SNMP and RMON)                 9  TCP/IP Internet Standard Management Framework Overview, Architecture, Components and Concepts

Overview and History of the TCP/IP Internet Standard Management Framework and Simple Network Management Protocol (SNMP) 1 2 3 TCP/IP Internet Standard Management Framework Architecture and Protocol Components

So, it seems the “Simple” Network Management Protocol (SNMP) isn't quite so simple after all. There are many versions and standards and uses of SNMP, and so a lot we need to learn. I think a good place to start in understanding what SNMP does is to look at its model of operation, and examine the components that comprise a TCP/IP network management system and the terminology used to describe them.

As we saw in the preceding high-level overview topic, the overall idea behind SNMP is to allow the information needed for network management to be exchanged using TCP/IP. More specifically, the protocol allows a network administrator to make use of a special network device that interacts with other network devices to collect information from them, and modify how they operate. In the simplest sense, then, two different basic types of hardware devices are defined:

• Managed Nodes: Regular nodes on a network that have been equipped with software to allow them to be managed using SNMP. These are, generally speaking, conventional TCP/IP devices; they are also sometimes called managed devices.
  
  
• Network Management Station (NMS): A designated network device that runs special software to allow it to manage the regular managed nodes mentioned just above. One or more NMSes must be present on the network, as these devices are the ones that really “run” SNMP.

Overview and History of the TCP/IP Internet Standard Management Framework and Simple Network Management Protocol (SNMP) 1 2 3 TCP/IP Internet Standard Management Framework Architecture and Protocol Components