SNMP - question / answer
The SNMP (Simple Network Management Protocol, MIB (Management Information Base) table) - SNMP Traps SNMP (Simple Network Management Protocol) is suitable for primary system information exchange using short packets sent via UDP/IP.
Individual variables are organized and described in so-called MIB (Management Information Base) table, which can be used for any device. The table is distributed as a separate .mib file that can be downloaded to Poseidon from our web pages or found on the supplied CD.
SNMP is an asynchronous protocol based on the client/server model (here SNMP Client/SNMP Agent). This means that the supervisor (SNMP Client) queries Poseidon for the state of the individual values in MIB held in the Poseidon and SNMP Agent, implemented in Poseidon, responds.
SNMP protocol support is provided in many languages intended for creating dynamic WWW pages (e.g. PHP, ASP, Java, Perl, Python and others). Thanks to existing modules it is possible to allow access to reading or writing the data, provided by peripheral device to the system (e.g. a Poseidon), over the SNMP protocol quite quickly.
In classic communication mode, the communication proceeds in terms of queries and responses. The variables are defined by a numeric string that is described in the MIB table that also defines the meanings of the individual variables, format and names. If you know the hierarchy (numeric string – e. g. „.1.3.6.1.4.1.21796.3.3.1.1.2.3“ – state of binary input 3) for a specific value, you don’t need the MIB table.
Basic terms:
* MIB table (Management Information Base) .mib file is a text-based file, describing individual variables supported by the device. It contains variables' addresses, their name, description and numeric format.
* OID (Object Identification) is an identifier of the variable in the variables’ chart. It is represented by a long number, defining the variable’s position within the variable tree structure.
Some programs do not support MIB files for working with SNMP. With these programs, you must enter the OID strings manually. The strings can be found in the MIB table, but to save you looking there, we provide a summary of several variables, their OID in Poseidon manual. |
