Connectivity Guide

• Description
• Data type of the variable (for example: integer, string, octet string)
• Whether the variable is accessible, not accessible, or read-only
• Index or indexes, if applicable
For each MIB group that has unique variable denitions, tables are included in the last section of the section to explain the meaning
of the terms.
Standards for writing MIBs are dened by the Internet Engineering Task Force (IETF). Structure of Management Information (SMI)
is a standard that species the rules for dening the structure and type of managed objects and events in a MIB. SMIv1 is specied
in Request For Comments (RFC) 1155. The Server Administrator MIB conforms to the SMIv1 standard.
SNMP is a systems management standard originally designed for network management. SNMP manages much more than networks.
Information Technology (IT) professionals use SNMP for monitoring and managing computer systems and the various components
and peripherals supported by their systems.
SNMP standards are dened by the Internet Engineering Task Force (IETF). SNMP version 1 was published in August 1988 and is the
most commonly supported version of SNMP. SNMP version 2 was rst published in May 1993, but has not gained widespread
market acceptance. SNMP version 3 was recently completed and has addressed security issues that exist in version 1.
All SNMP systems consist of one or more managed systems that provide data through an SNMP agent to a management system.
The management system provides a user interface to view data from the managed systems. The management system and managed
systems communicate over a network (typically through User Datagram Protocol/Internet Protocol [UDP/IP]).
The management system and a managed system communicate by means of a common data schema. SNMP MIB les dene the
structure, type, and values of the SNMP data. While MIBs can be standardized or enterprise specic, most operating systems supply
SNMP agents for the standard MIB-I and MIB-II schemas. MIB-I denes a base set of standard management information for
systems implementing the Internet Protocol (IP) suite. MIB-II denes characteristics of the system, characteristics of network
interfaces, and characteristics of components of the IP on the system. In addition to the standard MIBs, many hardware vendors
have dened MIBs that provide management data specic to their systems and peripheral devices.
Monitored data can be retrieved through SNMP using the Get command. Typically, this command requires the host name or IP
address of the target machine as well as the OID of the data to retrieve. Exact details are dependent on the operating system and
the development tools being used to create the management application. The Get command has a variant known as GetNext.
Management Information Base Object Identiers
Each data class within a Management Information Base (MIB) is dened by an Object Identier (OID). OIDs are unique across all
MIBs. An OID consists of a series of digits separated by periods. The OID functions in a similar fashion to a phone number. The phone
number 011-512-471-0000 uniquely identies a single phone. The phone number can be broken down into a number of components
to uniquely identify a phone. The rst component, 011, is the country code for the United States. The second component, 512,
identies the area code for central Texas. The third component, 471, is the phone exchange for a large state university in the city of
Austin. The nal component, 0000, is the main switchboard.
There are two main dierences between the phone number example and an actual OID. The rst dierence is that there are many
more components in an OID, up to 128. The combination of these components is called an OID prex. The second dierence is that
OIDs support the concept of indexes or keys. The OID prex species the data class but does not specify an instance of the data
within the class. Indexes can be used to identify the instances of a data class. These indexes are referred to as the OID sux.
The assignment of values for each OID prex component can be illustrated by using a tree structure. The following is an example of
an OID assignment:
Table 13. ROOT
CCITT(0)
ISO(1)
14