Admin-Down interface handling in EMC Smarts

EMC Smarts (aka IONIX) IP domain detects and reports on interfaces that have been configured as administratively down, but there are a couple of wrinkles to the way Smarts handles these situations that tend to cause confusion. This note is aimed at clarifying the logic.

If a router interface is set to admin down, and the interface is instrumented you should see this status reflected in the attributes of the relevant interface object..

  • The "Status" attribute should contain the word "DISABLED".
  • The "AdminStatus" should contain "DOWN".
  • The "OperStatus" should also contain "DOWN".

If you also view the fault instrumentation for the object (use dmctl or an un-filtered console) you should the same values there.

The status is polled from the MIB2 ifAdminStatus varbind for most interface types, but there are some devices that use alternative varbinds for this purpose. Provided the correct instrumentation variation is linked to the interface (ie: the interface is managed and the certification is correct) then the correct varbind should automatically be used, and the value it contains correctly interpreted.

If all these values are in place, then the IP domain will notify a "AdministrativelyDown" event on the instrumentation object. Under normal circumstances, this event will not be passed up into SAM, but this can be enabled by editing the DXA configuration file to add a suitable "sub" line (the "sev" is already there in the default file).

A "Disabled" problem will also be reported on the interface itself provided the interface has a peer (ie it is connected to another discovered interface) or the "SuppressDisabledNotifications" attribute of the interface is false (it is true by default).

The "SuppressDisabledNotifications" attribute can be a source of confusion because it doesn't quite do what it's name suggests. Many users think that setting this to true would suppress the "Disabledevent in all use cases, whereas it actually only suppresses the event if the interface has no peer (is not connected to anything). The default value of this attribute is "true", so the default behaviour in Smarts is to:

  • raise a "Disabled" root-cause event on interfaces that are admin down and have a discovered connection.
  • hide the "AdministrativelyDown" event in all cases.

If you are considering changing the default value of the "SuppressDisabledNotifications" attribute, you should also note the comment displayed against it in the console: that it is now obsolete.

 

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