MIB Roots

Because MIB definitions are written by different people, there is no rule as to how roots are handled. Some MIB definitions define absolute module root, some define relative module root, some MIB definitions don't, while others use an IMPORT directive to reference another MIB definition that would contain root definitions.

ScanEngine Explorer provides simple methods to define roots. The only trick is understanding what they are. Once you understand roots you should have no difficulty resolving unknown root definitions for any module you wish to load MIB definitions.

Every MIB in a MIB definition is defined with a complete numeric OID, or a relative numeric OID from a defined parent. In order to resolve the relative OID we must have the OID for parent.

For example, the ieee802dot11 module is typically defined as OID 1.2.840.10036. But elsewhere you might see a MIB for this same module defined as an OID relative to a parent, i.e. US.10036, where US is defined as MEMBER-BODY.840, MEMBER-BODY is defined as ISO.2, and ISO is defined as 1. It is often the case that a MIB is defined relative to a parent, but the parent definition is not included, or defined by an IMPORTS reference to a parent module MIB definition.

The final arbitor is whether ScanEngine Explorer has all reference roots defined. If not, loading MIBs will halt on encountering any unknown root, and the specifics written to program log.

Methods to define roots

• Enter absolute module roots directly into ScanEngine Explorer
  The roots panel in ScanEngine Explorer permits directly entering a list of root nodes. For example:
  ieee802dot11 1.2.840.10036
• Enter absolute module roots directly into MIB definition file
  It takes only 1 line to add an absolute OID to a MIB definition file
  For Example:
  ieee802dot11 OBJECT IDENTIFIER ::= { 1 2 840 10036 }
• Add parent definitions to MIB definition file
  For example, if the module identity is:
  ieee802dot11 MODULE-IDENTITY
  ::= { US 10036 }
  then add:
  member OBJECT IDENTIFIER ::= { iso 2 }
  US OBJECT IDENTIFIER ::= { member 840 }
  This, at minimum, requires that ScanEngine Explorer contains at least a single root: iso 1
• Insure that MIB definition file containing parent definition is loaded prior to any MIB definition that only uses relative definition
  If there is a MIB definition that defines the ieee802dot11 or parent, insure this MIB appears in the ScanEngine Explorer MIB Files panel before the ieee802dot11 MIB file. Typically, a MIB file may include an IMPORTS section of other modules that may be referenced. Obtain the MIB file that includes modules mentioned and place them first in the MIB Files panel.

ScanEngine Explorer provides both tree view and alphabetical panels for all loaded MIBs.