CA Spectrum alarm for WA_Link - Three or more devices connected by WA_Segment

Document ID : KB000109492
Last Modified Date : 02/08/2018
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Introduction:
I am seeing the event and alarm 0x10d57 in Spectrum:

An invalid Wide Area Segment association has been created for device <IPaddress>.The problem is Too-Many-Connections-To-WA_Segment-(>2).

THREE OR MORE DEVICES CONNECTED BY WA_SEGMENT

Symptoms:  SpectroSERVER may exhibit unpredictable behavior and instability.

Probable Cause:  The modeling scenario contains a Wide Area Link with a Wide Area Segment that is connecting more than 2 devices
Even though Spectrum allows such an association, this is not the intention of the design of the Wide Area Segment.

Actions:  Replace the Wide Area Link and Wide Area Segment models with a Fanout model. The Fanout model is designed for this task and will not cause instability in the SpectroSERVER
Question:
Why is Spectrum telling me this?  What should I do?
Answer:
Spectrum uses WA_Link models to represent a one to one (single port to single port) connection.  When you see this event/alarm, it is because the WA_Link is connected to more than 2 devices.  When the WA_Link is connected to more than 2 devices, this confuses Spectrum's internal Fault Isolation logic, and will cause undesirable alarming issues (for instance, you may not receive a proper alarm when the link goes down).  This could potentially happen in an environment running DMVPN.  Spectrum does not support DMVPN and therefore is confused when trying to model devices with many connections from the same port.  

Spectrum has two other models that are meant for a one to many connection.  They are the Fanout and the SharedMediaLink model.  Generally it is recommended to destroy the WA_Link and use a Fanout if the modeling connectivity is needed.  If there are 25 or more connections, you should use the SharedMediaLink modeltype instead.  These will need to be manually created and connected to the devices in question.