The newest version of the Nagios/Icinga plugin check_equallogic with version number 20140711 contains a snmp connection check. This was requested a lot over the last months and since I published the plugin on github (see https://github.com/Napsty/check_equallogic), there were even some issues and pull requests opened for that (thanks guys).
But instead of just creating a new check type (like -t snmp), I wanted that all checks are automatically using the snmp connection check. Otherwise every Nagios/Icinga admin would have to define service dependencies which would complicate configurations. Lame.
So the snmp connectivity check is defined as a function at the begin of the plugin which makes an snmp query and gets all the member names of the Equallogic group. This function is then used in all the checks so in case the snmp connection fails for reason XYZ, the checks all return the connection failure. Before that, some of the check types still returned "OK" even though the values from an Equallogic member couldnt be read.
The plan is also to use the information queried by the snmp connectivity check as global information for future checks (e.g. to check the values of only one member).
So again to summarize: The new snmp connectivity check is built-in and you don't need to change your configurations to enable it. Simply replace the plugin with the new version and you're good to go.
And I'll enjoy my birthday now.