The sat-nms software contains two SNMP agents which may be used to control the software from an external NMS.
Universal SNMP Agent
The universal SNMP agent publishes a limited number of device parameters in a fixed, table oriented MIB. This SNMP agent permits to monitor and partially control any sat-nms M&C using the same MIB - regardless of the device configuration of the particular M&C. The universal SNMP agent listens at port 2261, it is based on SNMPv2.
The MIB provides one table which contains all devices which are configured in the sat-nms M&C. No special mapping is necessary for this table as there are only very common parameters like the device name, its fault state or its administrative state in this table.
Beside this, the MIB contains a couple of tables, each representing all devices belonging to a so called 'device class'. For instance, there is one table containing all HPAs in the M&C and one table containing all waveguide switches. These class specific tables contain some parameters which are common to the devices of the particular class. The HPA table contains parameters for tx-on, for attenuation and forthe measured output power for each device, the waveguide switch table provides a parameter for the switch position.
As device drivers sometimes use different parameter names for the same or similar function, an individual mapping from the 'universal' parameter in the MIB to the real parameter in the device is necessary for every single sat-nms device driver. Device drivers which do not contain any information about the device class this devices belongs to and how the parameters are to be mapped into the MIB only appear in the in the general device table of the MIB.
A sat-nms device (physical or logical) may be represented by multiple device classes in the MIB or by multiple instances of the same class. For example a combined upconverter and HPA may appera as a HPA in this table (with its HPA specific parameters) and a second time in the upconverter table with its frequency parameter.
Also devices consisting of multiple modules can be treated this way in the MIB, there are quad block upconverter on the market which provide four independent converter modules in one device. Such a device can be mapped in way, that it appears as four BUC devices in that table.
By default the universal SNMP agent is disabled. Use the following keys in the vlc.properties file to enable the agent, set the read/write community strings and an optional list of trap/notification destinations. Each IP address in this list will receive a notification message for each device which changes its fault state. Example:
snmp.agent.enable=yes
snmp.agent.readCommunity=public
snmp.agent.writeCommunity=private
snmp.agent.trapTargets=192.168.0.89:2162 127.0.0.1:162'snmp.agent.trapTargets' defines a list of zero or more IP addresses in dotted quad notation. The addresses may contain a port number like in the example above, if no port number is specified, the standard SNMP trap port 162 is assumed. There is no fixed limitation in in the software for the number of trap destinations, you should however be aware, that a large number of destinations (greater than 10) may cause performance problems, depending on network speed and response time of the targets.
The agent sends a SNMPv2 notification (mncDeviceFaultChanged from the MIB) every time the fault state of a device changes. The notification message has the name of the device which caused the notification and its new fault state as varbinds attached. At program start, one initial notification message for each device is sent.
Application Specific SNMP Agent
The application specific agent provided by the sat-nms software is based on SNMPv1, it accepts requests at UDP port 2161. It permits read and write access from the 'public' community. Beside that, the sat-nms M&C may be configured to send SNMP traps on changes of certain parameters, e.g. fault flags.
Each M&C system is configured individually for the device setup it controls. Therefore also the SNMP agent configuration and the specific MIB for a M&C must be unique for each installed system. With the sat-nms M&C / VLC, the SNMP agent gets configured by a (text based) configuration file which defines the M&C parameters which shall be visible through SNMP.
The typical procedure to prepare the sat-nms M&C for SNMP access is as follows: