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Home > Success Center > Network Performance Monitor (NPM) > Clients do not show in Wireless Heatmaps, but all APs are present

Clients do not show in Wireless Heatmaps, but all APs are present

Created by Matthew Lamb, last modified by MindTouch on Jun 23, 2016

Views: 298 Votes: 1 Revisions: 5

Overview

This article describes the issue why clients sometimes do not show up in the Wireless Heatmap feature. This happens even if all APs are present from the WLC and the same controller shows multiple connections with the clients.

 

Environment

NPM version 11.5+

 

Cause 

The issue can occur when the clients are seen only on less than 4 APs (3 with a signal sampler) and cannot be triangulated correctly on the map. This is a common issue, but when all the APs are present in NPM and the WLC console shows more than 3 or 4 connections to multiple APs with sufficient strength, the problem occurs because of a lack of AP interfaces within NPM.

 

Typical errors for this issue can be found in the WLHM.BusinessLayer.log located under ProgramData\Solarwinds\Logs\Orion. Sample error message is displayed below:

2016-01-20 16:09:23,855 [27] WARN  SolarWinds.Wireless.Heatmaps.BusinessLayer.ClientLocation.ClientLocationCalculator - Unable to calculate position for client 'D8FC938B581C'. Exception: System.ArgumentOutOfRangeException: Not enough points at input, needs 3, has 1
Parameter name: points
   at SolarWinds.Wireless.Heatmaps.BusinessLayer.ClientLocation.Algorithm.PowerCenterCalculator.CalculateLocation(IEnumerable`1 points)
   at SolarWinds.Wireless.Heatmaps.BusinessLayer.ClientLocation.Algorithm.IntersectionsAlgorithmBase.CalculatePosition(IEnumerable`1 measurements)
   at SolarWinds.Wireless.Heatmaps.BusinessLayer.ClientLocation.ClientLocationCalculator.CalculateInternal().

 

As seen, the client device is only being seen on 1 AP, but needs 3 to map properly. Each point of connection is based off ALL of the interfaces for the AP in question, or antennas. Some WLC devices do not provide all the interfaces for the APs and these will not be known or compared in NPM. The amount of connections that device has to the AP is severely limited and will not show correctly.

 

This information is stored in the Wireless_Interfaces table within the database. Each one of the interfaces is an antennae off the AP and should be stored here and linked to the ParentID (AP).

 

Each one of these interfaces has its own signal value for a client MAC address in the environment and should be stored on the WLC controller. Information on the OIDs to poll this through SNMP can be found here.

 

Once that information is gathered, it is then stored in the WirelessHeatMap_ClientMeasurement table in the database. Each client has its RSSI values stored with the interface it has gathered from the list.

 

 

Based off the error above concerning client D8FC938B581C, you can see that it is showing a connection to 5 different antennae MACs with the RSSI values displayed. However, the RSSI values are all little to no connection, with the exception of 0x002255EFB670 which shows an RSSI of 54. This is the only valid RSSI value that Wireless Heatmap will be able to accept, hence it only has 1 connection.

 

However, if you were to check the WLC device, you would see that there would be many more RSSI values with a better rating, but they are on interface MAC addresses that are not stored in the Wireless_Interfaces table. When running an snmpwalk on the WLC device, it's found that the the device will not report back all the Interface MACaddresses correctly.

Resolution

  • Verify that all the AP interface MACAddresses are populated through SNMP.
  • Ensure that if using SNMPv3, sufficient MIB privileges are provided
  • Contact the WLC vendor for assistance on having that information provided.

 

 

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