Unexpected alarm behavior in Spectrum for Security Appliances behind SDC connected via WA_Link

Products

• Network Observability
• Spectrum

Issue/Introduction

There are routers and Security Appliances discovered in Spectrum.

The routers are directly connected, while the Security Appliances are coming via SDC in Spectrum.

We have created the WA_Segment and WA_Link relationships between routers and Security Appliances on a on-to-one basis (the way they are connected in real environment).

The objective was to avoid duplicated alarms when a router goes down, specifically, to ensure that when a router goes down, the associated Security Appliance alarm is suppressed.

However, we are observing unexpected behavior:

• When a router goes down, a "Device Stopped Responding to Polls" alarm is generated, which is expected.
• But when a Security Appliance goes down (even though the router is up and Wa_Link exists), Spectrum raises an "Unresolved Fault Detected" alarm instead of the expected "Device Stopped Responding to Polls" alarm.

Environment

DX NetOps Spectrum: Any version

Resolution

Change the WA Link Fault Isolation Mode from Normal to Transparent under the Fault Isolation subview of the VNM model. It specifies whether WA_Link models are considered neighbors for fault isolation purposes. Changing to Transparent implies that when the Security Appliance does down, Spectrum asks the router if it is down instead of the WA_Link.

Additional Information

There might be several reasons why this is happening:

1. Wa_link has not been created properly to participate on the fault isolation - See Inferred Connector Fault Isolation example and False Fault Isolation Unresolved Fault Detected Alarms
2. Wa_link should be configured in Transparent Mode so that Spectrum asks the router during the fault isolation - See WA Link Fault Isolation Mode
3. SDC has been modeled as an application model impacting the proper execution of the fault isolation - See Enable Fault Isolation capability for SDM/SDC managed devices and  Reconfigure Spectrum SDM/SDC configuration and modeling