1-30
Cisco SRST SNMP MIB Release 3.4 Guide
OL-7959-01
Chapter 1 Cisco SRST SNMP MIB Support
Internet MIB Hierarchy
As shown in
Figure 1-3
, the SNMP agent gathers data from the MIB, which is the repository for
information about device parameters and network data. The agent can send traps, or notifications of
events of interest, to the manager. The Cisco trap file, mib.traps, which documents the format of the
Cisco traps, is available on the Cisco host ftp.cisco.com.
Figure 1-3
Simple Network Management Protocol Network
The SNMP manager uses information in the MIB to perform the operations described in
Table 1-5
.
1. With this operation, an SNMP manager does not need to know the exact variable
name. A
sequential search is performed to find the needed variable from within the MIB.
Internet MIB Hierarchy
The MIB structure is logically represented by a tree hierarchy (see
Figure 1-4
). The structure uses
branches and the branches that fall below each category have short text strings and integers to identify
them. Text strings describe object names, and integers allow computer software to create compact,
encoded representations of the names. For example, the Cisco MIB variable authAddr is an object name
and is denoted by number 5, which is listed at the end of its object identifier number 1.3.6.1.4.1.9.2.1.5.
The object identifier in the Internet MIB hierarchy is the sequence of numeric labels on the nodes along
a path from the root to the object. The Internet standard MIB is represented by the object identifier
1.3.6.1.2.1. It also can be expressed as iso.org.dod.internet.mgmt.mib. (See
Figure 1-4
.)
Table 1-5
SNMP Manager Operations
Operation
Description
get-request
Retrieve a value from a specific variable.
get-next-request
Retrieve the value following the named variable. Often
used to retrieve variables from within a table.
1
get-response
The reply to a get-request, get-next-request,
get-bulk-request, or set-request sent by an NMS.
get-bulk-request
Similar to a get-next-request, but fill the
get-response with up to max-repetition number of
get-next interactions.
set-request
Store a value in a specific variable.
trap
An unsolicited message sent by an SNMP agent to an
SNMP manager indicating that some event has
occurred.
