Simple Network Management Protocol (SNMP)
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PHOENIX CONTACT
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Simple Network Management Protocol (SNMP)
3.1
General function
SNMP is a manufacturer-independent standard for Ethernet management. It defines com-
mands for reading and writing information, and defines formats for error and status mes-
sages. SNMP is also a structured model that consists of agents, their relevant Management
Information Base (MIB) and a manager. The manager is a software tool that is executed on
a network management station. The agents are located inside switches, bus terminal mod-
ules, routers, and other devices that support SNMP. The task of the agents is to collect and
provide data in the MIB. The manager regularly requests and displays this information. The
devices can be configured by writing data from the manager to the MIB. In the event of an
emergency, the agents can also send messages (traps) directly to the manager.
SNMP interface
All managed Factoryline components have an SNMP agent. This device agent manages
Management Information Base II (MIB 2) according to RFC1213 and private SNMP objects
from the Phoenix Contact MIB (PXC-WLAN-MIB).
Network management stations, such as a PC with Factory Manager, can read and modify
configuration and diagnostic data from network devices via the Simple Network Manage-
ment Protocol. In addition, any SNMP tools or network management tools can be used to
access Factoryline products via SNMP. To do this, the MIBs supported by the relevant
device must be made available to the SNMP management tools.
On the one hand, these are globally valid MIBs, which are specified and described in RFCs
(Request for Comments). This includes, for example, MIB2 according to RFC1213, which
is supported by all SNMP-compatible network devices. On the other hand, manufacturers
can specify their own SNMP objects, which are then assigned to a private manufacturer
area in the large SNMP object tree. Manufacturers are then responsible for their own private
(enterprise) areas, i.e., they must ensure that only one object is assigned to an object ID
(object name and parameters) and can be published. If an object is no longer needed, it can
be labeled as “expired”, but it cannot be reused with other parameters under any circum-
stances.
Phoenix Contact provides notification of ASN1 SNMP objects by publishing their descrip-
tions on the Internet.
Reading SNMP objects is not password protected. However, a password is required for
read access in SNMP, but this is set to “public”, which is usual for network devices, and can-
not be modified. By default upon delivery, the password for write access is “private” and can
be changed by the user.
Another benefit for the user is the option of sending traps using the Simple Network Man-
agement Protocol.
All configuration modifications, which are to take effect after a device restart, must be
saved permanently.
For SNMP the password “public” is used for read-only access, the password “private” for
read/write access.
