Fault Isolation is not working when Access Points (APs) are discovered using WLC manager

Products

• CA Spectrum
• DX NetOps

Issue/Introduction

Experiencing a problem with Fault Isolation/alarm suppression specifically for Cisco WLC Manager devices where Switches are discovered as an SNMP device with a parent/upstream device. It has a number of child/downstream devices. When the parent device goes down, all downstream devices are not being suppressed. Instead, Spectrum creates a high number of alarms, one for each device so Fault Isolation does not appear to suppress them.

Fault isolation is working fine when devices are discovered from discovery console but it is not working when Access Points (APs) are discovered using WLC manager.

 

Environment

DX NetOps Spectrum - 20.2 or later
OS - Linux/Windows

Resolution

In circumstances like this, the simplest way to fix the issue would be to delete the APs and rediscover. However, if you can not delete the existing APs and re-discover again, then change the value of "Discover connection only towards Access Points" to No and run the Access Point Discovery again:

If any new AP's are added to WLC manager, this will discover them. 

What this does is, it will read the respective MIBs and if changes are observed, then it will update those APs. If the information stored in inventory and WLC MIB's are up to date, then it won't make any changes to existing AP's so it's not certain it will effect existing AP's or not, but this will make the relations between APs and WLC and AP attributes up to date.  Which means it will more accurately reflect your topology.

It all depends on the information stored with WLC and options you set on WLC manager. The options such as Move Access Points along with WLC and schedule discovery on WLC manager may make some impact. 

With regards to fault isolation, when we set Discover connection only towards Access Points to Yes, it will read only CDP and SAT tables of APs to determine upstream switches and then make connections.

But when this option is set to No, the protocol options set in VNM model is used for determining upstream connections to the access points. In other words it is almost the same as discovering access points by using discovery console. As Fault Isolation (FI) is working properly when discovering Access Points using the discovery console, then setting Discover connection only towards Access Points to No should also make FI work properly as the same protocols are used for determining upstream switches.