Configuring NSX on an ESXi host fails with an error referencing MTU settings on an uplink profile
Article ID: 373135
Updated On:
Products
Issue/Introduction
When attempting to configure a host as a transport node, it fails with Error:
VDS [<name>] does not need field MTU to be specified in its uplink profile [BaseHostSwitchProfile/<UUID>]. Keep the field MTU in uplink profile for a VDS switch empty. Field MTU for VDS has to updated from vSphere. (Error code: 9531)
Review of Uplink Profiles in use shows MTU setting other than "1700 (Global MTU)", the default value displayed when the profile's MTU field is left blank. The example below from a generic lab environment shows an uplink profile with an MTU configured to a custom value.
Cause
Prechecks when attempting to add a node to a cluster will fail if an uplink profile has an MTU setting that is not consistent with the Virtual Distributed Switch the host will connect to.
Refer to Configuring a vSphere Distributed Switch which states: "As a host transport node that is prepared using VDS as the host switch, the MTU value needs to be set on the VDS switch in vCenter Server."
MTU specification, other than default by leaving the field blank, is still an option to set with an Uplink Profile when the nodes to which it will be assigned will not be on a Virtual Distributed Switch.
Resolution
At System > Configuration > Fabric > Profiles, select and edit the applicable Uplink Profile then delete the MTU value at the bottom of the window to leave it blank, then click Save.
Afterwards, you can run the normal process for Preparing ESXi Hosts as Transport Nodes and it should no longer fail the precheck.
Additional Information
Create an Uplink Profile explains all the various settings in an uplink profile that can be applied to a Transport Node by selecting as part of a Transport Node Profile attached to a host or a cluster of hosts configured as transport nodes in NSX Manager.
Also see Guidance to Set Maximum Transmission Unit with other helpful information.
If you are contacting Broadcom support about this issue, please provide the following:
- vCenter Server and ESXi host log bundles for the affected cluster
- Ensure log date range covers the full date of the event(s) being investigated. When in doubt, retrieve logs for all time.
- NSX Manager log bundles
- Text of any error messages seen in NSX GUI or command lines pertinent to the investigation
Handling Log Bundles for offline review with Broadcom support
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