30.13 Summary

　　Network management protocols allow a manager to monitor and control routers and hosts. A network management client program executing on the manager's workstation contacts one or more servers, called agents, running on the devices to be controlled. Because an internet consists of heterogeneous machines and networks, TCP/lP management software executes as application programs and uses internet transport protocols (e.g., UDP) for communication between clients and servers.

　　The standard TCP/IP network management protocol is SNMP, the Simple Network Management Protocol. SNMP defines a low-level management protocol that provides two conceptual operations: fetch a value from a variable or store a value into a variable. In SNMP, other operations occur as side-effects of changing values in variables. SNMP defines the format of messages that travel between a manager's computer and a managed entity.

　　A set of companion standards to SNMP define the set of variables that a managed entity maintains. The set of variables comprise a Management Information Base (MIB). MIB variables are described using ASN.1, a formal language that provides a concise encoded form as well as a precise human-readable notation for names and objects. ASN.1 uses a hierarchical namespace to guarantee that all MIB names are globally unique while still allowing subgroups to assign parts of the namespace.

Abstract from Internetworking With TCP/IP Vol I: Principles, Protocols, and Architecture Fourth Edition,

DOUGLAS E. COMER,

Department of Computer Sciences Purdue University, West Lafayette, IN 47907,

PRENTICE HALL,

Upper Saddle River, New Jersey 07458