It is not uncommon to see more than two models connected to the same Fanout, Unplaced or WA_Link/Segment model. Although allowed, having too many models connected to the same Fanout, Unplaced or WA_Link/Segment model can result in one or all of the following to occur:
1. Fault Isolation taking a long time to assert and clear alarms.
2. Model Activation after starting the SpectroSERVER taking a long time to occur
3. SpectroSERVER performance issues
4. Fanouts connected to fanouts generate an alarm for Inferred Connector Contact Status Lost
5. SpectroSERVER crash in the CsIHInfIsolation where the following is seen in the stack trace:
#10 0x00007f10e40d29bd in CsIHFaultBase::send_nbors_action(CsULongList*, CsAction*, CsModelHandle) () from /opt/SPECTRUM/lib/../SS/libmdlsvint.so.1
#11 0x00007f10e40dfb3e in CsIHInfIsolation::get_good_DS_neighbor(CsModelHandle const&, CsModelHandle const&) ()
#12 0x00007f10e40e0025 in CsIHInfIsolation::are_you_up(CsModelHandle const&, CsModelHandle const&) () from /opt/SPECTRUM/lib/../SS/libmdlsvint.so.1
#13 0x00007f10e40df030 in CsIHInfIsolation::trig_action(CsModelHandle const&, CsAction const*, CsConnHandle const&) ()
Fanouts have fault isolation code to query all connected models for status when one connected device loses contact.
The following is noted in the "AutoDiscovery Control Subview" section of the Spectrum documentation:
Note: If you have 50 or more connections to a single Fanout model, consider changing this model to a Shared Media Link. The Shared Media Links must be modeled manually. These models can provide more control over fault management behavior when multiple connections are monitored. Unlike a Fanout model, Shared Media Links provide configurable thresholds for handling downstream connections that report problems. For example, a Fanout model reports a problem only when all downstream connections are down. However, a Shared Media Link can report the problem sooner, as when 60 percent of the downstream connections are down.
The above note also applies to the Unplaced and WA_Link/Segment models.
For Spectrum 21.2.6 and above, the following two parameters can be placed into the $SPECROOT/SS/.vnmrc file that will replace existing Fanout models with Shared Media Link (SML) models.
max_fanout_connections=5 (default value is 10 means only migrate the fanout to SML only if its connected neighbors are more than or equal to 10)
After adding the above parameters to the .vnmrc file, a SpectroSERVER restart is required.
The following parameter can be added for WA_Link models that may cause the same issue:
Reference the "Migration to Shared Media Link (SML) (.vnmrc) Resources" section of the Spectrum documentation for more details.
For Spectrum 21.2.5 and below:
To replace the Fanout, Unplaced or WA_Link/Segment model with a SharedMediaLink model:
1. Note the interface models of the device models connected to the existing Fanout, Unplaced or WA_Link/Segment model. This can be done by clicking on the link between the Fanout, Unplaced or WA_Link/Segment model and the device model and noting the interface in the Link Information view
2. Create the new SharedMediaLink model
3. Right mouse click on the link between the Fanout, Unplaced or WA_Link/Segment model and the device model select Delete from the menu
4. Right mouse click on the SharedMediaLink model and select Start Connection from the menu
5. Select the device model where you deleted the link between it and the Fanout, Unplaced or WA_Link/Segment model in step 3
6. Click on the Interfaces tab in the Component Detail panel
7. Find the interface noted in step 1 above and select. Right mouse click on the interface and select Connect With from the menu