User manual

SNMP
33002479 06 07/2008 229
Configuring an NOE with SNMP
Object Identifier
(OID)
In the ASN.1 Naming Scheme example (see An Example, p. 227), the MIB object
identified by the notation 1.3.6.1.2.2.4.3 is referred to as the Object Identifier or OID.
All OIDs can be seen as part of a tree structure that begins at the root (ISO) and
branches out with each subtree identified by an integer.
SNMP Protocol
Data Units
SNMP uses protocol data units (PDUs) to carry the requests and responses,
between the manager and the agents, for the information contained in an OID.
As the following figure shows, the SNMP message is the innermost part of a typical
network transmission frame.
The PDUs within the SNMP initiate the communication between the manager and
the agents.
The SNMP installed on your NOE module uses the following three PDUs:
z GetRequest
z SetRequest
z Trap
GetRequest PDU The GetRequest (shortened to Get) PDU is used by the SNMP manager to retrieve
the value of one or more objects (OIDs) from an agent.
SetRequest PDU The SetRequest (shortened to Set) PDU is used by the SNMP manager to assign a
value to one or more objects (OIDs) residing in an agent.
Trap PDU The Trap PDU is used by the agent to alert the manager that a predefined event has
occurred.
IP
Header
Local
Network
Header
UDP
Header
SNMP
Message
Local
Network
Trailer
Version Community
GetRequest, SetRequest,
or Trap PDU