System information

332 Observer Suite: SNMP Management
(All other MIBs are extensions of this basic management information base.) MIB-I refers
to the initial MIB definition; MIB-II refers to the current definition. SNMPv2 includes
MIB-II and adds some new objects.
Each MIB has a name, a syntax, and an encoding.
• Name—identifies the object
• Syntax—defines the object’s structure (e.g., octet string, integer).
• Encoding—an object’s representation using the object’s syntax (e.g., “the local IP
address for this TCP connection,” “Read Only,” or “Mandatory”).
When requested, the SNMP agent transfers an SNMP message across the network in a
standard format, as specified by the set of SNMP Request for Comments (RFCs). Related
MIB objects often are combined into MIB groups. MIB groups make it easier to manage a
large number of MIB objects. Some MIBs, such as the standard MIB-2, contain many
MIB groups. Proprietary MIBs usually have only one, or a few, groups.
OIDs
An Object Identifier (OID) is a unique identifier assigned to a specific object. The
identifier consists of a sequence of numbers that identify the source of the object, as well
as the object itself. This sequence of numbers is variable in length, so in addition to the
sequence of numbers, there is a length field. OIDs are organized in a tree structure; the
sequence of numbers identifies the various branches of the subtree that a given object
comes from.
The root of the tree is the ISO (International Standards Organization) trunk. Its value is
one (1). Each branch below the root further identifies the source of the given object. All
SNMP objects are members of the subtree identified by iso.org.dod.internet or 1.3.6.1.
Each additional component further defines the exact location of an object. The numbers
for each subtree are assigned by the IETF to ensure that all branches are unique. While it is
good to know that OID identification structure exists, in general, OID management is
Example:
SYSDESCR = the object descriptor
1.3.6.1.2.1.1.1 = the object identifier
Example:
Object: TCPConnLocalAddress
Syntax: Integer
Definition: The local IP address for this TCP connection
Access: Read only
Status: Mandatory