SNMP Configuration and Management Manual

SNMP Configuration and Management Manual—424777-006
9-1
9 EMS Trap Subagent
The EMS Trap Subagent translates Event Management Service (EMS) events into
SNMP traps whose objects are defined in the EMS Trap MIB. This section describes
the EMS Trap Subagent and its MIB.
Architectural Overview
EMS is a set of processes that collect event messages and then distribute them to
various destinations, such as viewing consoles and printers. Event messages,
generated by most HP subsystems and by many customer applications that run on
NonStop systems, describe significant situations, such as loss of a function or need for
operator action. Many of these events are candidates for traps for SNMP managers.
Figure 9-1 identifies some of the EMS processes and the objects they use:
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Event messages are sent by subsystems and applications to one or more
collectors. A collector known as $0 is configured at system generation and this is
the primary collector. Other (alternate) collectors can be started after the system
load.
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Each collector writes the events it receives to a log file.
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Distributors read events from log files and route them to specific destinations.
Different kinds of distributors support different destinations, as the figure illustrates.
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Distributors can be configured to use a filter to select events to route.
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Events that need to be read as text can be formatted by using a template. A
template provides instructions for how information should be displayed. Templates
can be used by subsystems and applications, as well as by printing and
compatibility distributors.
As Figure 9-2 indicates, the EMS Trap Subagent is implemented within EMS as a
special kind of printing distributor known as a routing distributor. Routing distributors
use destination information encoded in filters to determine where to send selected
events. To optimize fault tolerance for the EMS Trap Subagent, the routing distributor
can be run as a process pair.
You define a filter to identify which event messages to convert into trap messages and
to identify the agent process to which to forward them. The EMS Trap Subagent
constructs trap messages by using an EMS template in ZSMPTMPL and then forwards
the traps to the SNMP agent. The SNMP agent sends trap messages to SNMP
managers configured to receive them. These SNMP managers can interpret the traps
after the EMS Trap MIB definition has been installed.