Spectrum Fault Isolation not working correctly for devices connected to the VNM
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Spectrum Fault Isolation not working correctly for devices connected to the VNM


Article ID: 132467


Updated On:


CA Spectrum DX NetOps


When modelling the VNM in the landscape by connecting it to the nearest switch, it returns a black Link: Unable to Render Topology.

Looking at the Neighbors of the switch, the VNM is not there. Looking at the attribute 0x12a8c (Neighborlist), this does not update.

Testing the fault isolation when disabling the switch, it suppresses the connected switch immediately, together with all attached devices after the switch.

One would expect an alarm to be present. The simple rule of thumb for creating connections is:

  1. Any connectivity between the device to device (high -level) should trigger the auto-discovery to resolve the connection, if not resolved it will be shown as black pipe.
    e.g. connection between Device A (high level) <-> Device B (high level).

  2. Connectivity between port level to port level is considered as customer specified and spectrum create the connection.

  3. Cross-connectivity also treated as customer specified (port -> device / device -> port).

    e.g   VNM model <-> fanout : -> This will work, since fanout connectivity is treated as port level.
    Since the basic concept of fanout is accepting multi-port connectivity

    e.g.   VNM model <-> device (high -level) : -> it will come up as black pipe, since auto discovery won't resolve the connection.

    e.g. VNM model <-> device port level : -> will work.


DX NetOps Spectrum Release: 20.2 or later


For situations where the VNM model is not actually connected to a device in the landscape, e.g. such as tenanted environments, you should change the fault isolation settings on the VNM model, to place the alert on a device in the fault domain.  

The default behavior is to place alerts on the fault isolation model. This is found on:

VNM model -> Fault Isolation subview -> "Unresolved Fault Alarm Disposition"

Additional Information

TechDocs : DX NetOps 21.2 Spectrum : Fault Isolation

TechDocs : DX NetOps 21.2 Spectrum : Fault Isolation Settings