Error: Port mirroring session creation fails due to VLAN conflict with Distributed Port Group in vSphere 9.1.

Products

• VMware vCenter Server

Issue/Introduction

When you attempt to create a Port Mirroring Session (Remote Mirroring Destination), the creation fails and you observe the following alerts:

• A specified parameter was not correct: spec.vspanConfigSpec[].vspanSession.sourcePortReceived.vlans

• The VLAN ID <VLAN Number> in the mirror session has been used by Distributed Port Group <PortGroup Name>

Additionally, you see the following log excerpt in the vpxd log on the vCenter Server:

vim.DistributedVirtualSwitch.reconfigure: :vmodl.fault.InvalidArgument
--> Result:
--> (vmodl.fault.InvalidArgument) {
-->    faultCause = (vmodl.MethodFault) null,
-->    faultMessage = (vmodl.LocalizableMessage) [
-->       (vmodl.LocalizableMessage) {
-->          key = "com.vmware.vim.vpxd.dvs.mirror.sourceVlanConflict.label",
-->          arg = (vmodl.KeyAnyValue) [
-->             (vmodl.KeyAnyValue) {
-->                key = "vlanId",
-->                value = "2"
-->             },
-->             (vmodl.KeyAnyValue) {
-->                key = "dvpg",
-->                value = "PortGroup-Name"
-->             }
-->          ],
-->          message = <unset>
-->       }
-->    ],
-->    invalidProperty = "spec.vspanConfigSpec[].vspanSession.sourcePortReceived.vlans"
-->    msg = ""
--> }

Environment

 

• VMware Cloud Foundation 9.1

• VMware vSphere 9.1

 

 

Cause

VMware vSphere 9.1 includes a validation mechanism that disallows configuring a Remote Switched Port Analyzer (RSPAN) VLAN that matches a Distributed Virtual Port Group (DVPG) access VLAN, a DVPG trunk VLAN, or a Private VLAN (secondary VLAN). This validation prevents the creation of the mirroring session and blocks upgrades if an RSPAN VLAN conflicts with any of these production VLANs.

Resolution

To resolve this issue, you must configure the RSPAN VLAN as a dedicated VLAN. The VLAN ID used in the RSPAN Source and RSPAN Destination mirroring types cannot conflict with any existing production VLANs.

1. Identify an unused VLAN ID in your environment.

2. Assign this dedicated, non-conflicting VLAN ID to your RSPAN configuration.

Additional Information

Traffic for VMs on specific VLANs dropped by the host after upgrading NSX-T to version 4.2