For a single SNMP agent running on a device, each OID has a unique
meaning defined in the relevant MIBs. Devices with SNMP management
boards which can be configured in Check_MK, however, can have
multiple SNMP agents relevant to the device. A Check_MK check plugin
therefore needs to be able to distinguish between data sent by the
management board and data sent by the host itself to avoid picking
Both data sources provide data for this check plugin and it's not
clear which one should be used.
We address this problem as follows:
In the case of multiple data sources which would use the same check
plugin we implement new ones with the same functionality.
Moreover a new check_info attribute 'management_board' is introduced
which can have one of the following four values:
Use management board address/credentials eg. when it's a SNMP host.
Otherwise host's address/credentials are used.
Check is only executed for management boards.
Use host address/credentials eg. when it's a SNMP HOST
Check is only executed for real SNMP hosts.
Furthermore these management board specific services have the
prefix 'Management Interface: ' in their service description.
Example: snmp_uptime and mgmt_snmp_uptime.
snmp_uptime is used for SNMP host and mgmt_snmp_uptime is used
for the related SNMP management board. Second one has the
service description 'Management Interface: Uptime'.
Notes for check plugin development:
- Management board specific check types have the check_info
attribute 'management_board' set to 'MGMT_ONLY'. The service
descriptions of these plugins must start with
'Management Interface: '.
Convention: Prefix 'Management board'-ONLY check plugin names
At the moment the check_info attribute 'management_board' is
only used for SNMP check types.
The default value of check_info attribute 'management_board'
Use this key if a host may have a management board. If yes
this check type uses the management board as data source,
otherwise the host's one.
Use this key if a host and its SNMP management board provide
data for the same check plugin.
In order to avoid overlapping discoverable services, create
two check plugin types with same functionality. Make use of
One is used for the host itself, the other one has the additional
service description prefix 'Management Interface: ' and uses the
check_info attribute 'management_board' which is set to MGMT_ONLY.
Example: Have a look at the snmp_uptime and mgmt_snmp_uptime
checks which are a good example for this feature.
Always use the SNMP host's credentials regardless whether this host
has a management board or not.
This check plugin will be used if you want to contact a real
host and not a management board.
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