SNMP module on IP Trade devices

Variable access

All IP Trade device SNMP variables have a maximum access right set to read-only. That means SNMP cannot be used to configure IP Trade device, the SNMP purpose is limited to system activity monitoring.

Variable types

Depending on their signification, variables may be setup on system start up and never change along execution; or continuously be updated along system activity.

a.Punctually updated variables

Some variables do not change at all while the system is running (for instance: total memory) some others change punctually depending on particular event occurrence in the system (for instance: authenticated user on a turret). Those kinds of variables are qualified “punctual”: they are punctually set by the application when particular events occur.

b.Continuously updated variables

Some variables are continuously changing all along the system execution (for instance: number of sent packets). That kind of variables is qualified “continuous”: they are maintained by the applicative layer and requested by SNMP module on SNMP management entity demand or on trap check.

In order to avoid SNMP module request burst, a validity period is defined for each “continuous” variable. That way the value stored in SNMP module for a particular variable remains valid during a preconfigured period.

Once a value has been received from applicative layer, SNMP module stores it for further requests. If subsequent requests come in before variable expiration, SNMP module answers those request directly without requesting a value update to the applicative layer.