Carrier-Grade Alarm System - Nortel Media Gateway 3200 User Manual

H.248 User's Manual
By convention, SNMP objects are always grouped in an "Entry" directory, within an object
with a "Table" suffix. (The "ifDescr" object described above resides in the "ifEntry" directory
contained in the "ifTable" directory).
8.1.1.3 SNMP Extensibility Feature
One of the principal components of an SNMP manager is a "MIB Compiler", which allows
new MIB objects to be added to the management system. When a MIB is compiled into an
SNMP manager, the manager is made "aware" of new objects that are supported by
agents on the network. The concept is similar to adding a new schema to a database.
Typically, when a MIB is compiled into the system, the manager creates new folders or
directories that correspond to the objects. These folders or directories can typically be
viewed with a "MIB Browser", which is a traditional SNMP management tool incorporated
into virtually all network management systems.
The act of compiling the MIB allows the manager to know about the special objects
supported by the agent and access these objects as part of the standard object set.
8.1.2

Carrier-Grade Alarm System

The basic alarm system has been extended to a carrier-grade alarm system. A carrier-
grade alarm system provides a reliable alarm reporting mechanism that takes into account
element management system outages, network outages, and transport mechanism such
as SNMP over UDP.
A carrier-grade alarm system is characterized by the following:
The device allows an EMS to determine which alarms are currently active in the
device. That is, the device maintains an active alarm table.
The device allows an EMS to detect lost alarms and clear notifications. [sequence
number in trap, current sequence number MIB object]
The device allows an EMS to recover lost alarm raise and clear notifications
[maintains a log history]
The device sends a cold start trap to indicate that it is starting. This allows the EMS to
synchronize its view of the device's active alarms.
When the SNMP alarm traps are sent, the carrier-grade alarm system does not add or
delete alarm traps as part of the feature. This system provides the mechanism for viewing
of history and current active alarm information.
8.1.2.1 Active Alarm Table
The board maintains an active alarm table to allow an EMS to determine which alarms are
currently active in the device. Two views of the active alarm table are supported by the
agent:
acActiveAlarmTable in the enterprise AcAlarm
alarmActiveTable and alarmActiveVariableTable in the IETF standard AcAlarm MIB
(rooted in the MIB tree)
The acActiveAlarmTable is a simple, one-row per alarm table that is easy to view with a
MIB browser.
Version SN09 125
8. MG 3200 Management
October 2006