Network Management

Dell switches missing endpoints on VLANs

This article goes over and describes why Dell based layer 2 switches would be missing endpoints for ports assigned to VLANs in User Device Tracker.

First published date

11/29/2018 10:55 PM

Last published date

11/29/2018 10:55 PM

Overview

This article goes over and describes why Dell based layer 2 switches would be missing endpoints for ports assigned to VLANs.

Product section

User Device Tracker

Resolution

For the most part, Dell based switches provide their port and endpoint information the same as other models such as Cisco. However, the polling of the devices through UDT can result in missing VLANs and\or missing endpoints. The reason for this involves the results of the following OIDS:

  • dot1qVlanCurrentTable (1.3.6.1.2.1.17.7.1.4.2)
  • vmMembershipSummaryTable (1.3.6.1.4.1.9.9.68.1.2.1)
  • dot1qTpFdbTable (1.3.6.1.2.1.17.7.1.2.2)
  • OPTIONAL: vtpVlanTable (1.3.6.1.4.1.9.9.46.1.3.1)

 

The purpose of these OIDs are described here: SNMP Context polling in UDT. In Dell models however, there is a bit of a difference. In this case, the second OID in the list, vmMembershipSummaryTable, is exclusive with Cisco and not with Dell devices. The OID dot1qVlanCurrentTable provides the VLANs on the device, but does not provide the ports that are assigned to these VLANs like vmMembershipSummaryTable does. 

 

Because of this, when UDT attempts to query the endpoints through dot1qTpFdbTable, it will only do so based off the default OID, which falls into the default vlan as well. So when a customer looks at the VLANs for their Dell switches, they will typically see only the default vlan and only the endpoints in that vlan.

 

In regards to vtpVlanTable, this is an OID that is based off a possible implementation directly by SolarWinds Support. It will provide the vlan and port assignment information for UDT to use. However, that OID must be supported by the device as well. If it is supported, you can contact Dell Support for assistance in retrieving it.

 

 

Typical OID poll from a Dell switch:

 

There is currently no workaround at this time if the device does not poll VLAN to port assignment OIDs as listed above. If you would like to see this added in at a later date, please feel free to contact SolarWinds Support to submit a feature request for an alternative method of polling be added in specifically for Dell devices.