One of VMware NSX’s best features is the ability to have the VXLAN Control Plane working in Unicast Mode…removing the requirement for Multicast traffic on the underlying Physical network. This is a significant step forward in that Multicast often created issues for traditional network teams and getting it retrofitted to an existing platform was often a challenge.

Note: As mentioned in my previous post…these NSX bytes are not meant to contain detailed info regarding NSX Components…for more info on the VXLAN Enhancements in NSX, check our Anthony Burke’s NSX Compendium here: And read up on the different Transport Modes here:

Back to the error I came across whilst configuring the Transport Zones in my lab…The lab was an upgraded 5.1 vCenter to 5.5 deployment with a mixture of ESXi 5.1 and 5.5 Hosts and Clusters. After the Controllers where deployed and the Hosts and Clusters prepared I went about the Logical Network Preparation and enabled the VXLAN Transport and Segment ID.

When attempting to configure the Transport Zones I received these errors when trying to create Unicast or Hybrid Zones.

NSX_transport_error_1NSX_transport_error_2.JPGI checked back through the NSX Documentation for the System Requirements and by the letter of the law, everything checked out.


I had my vCenter 5.5, ESXi 5.5 and had prepped the VXLAN transport network as instructed. Checking through the platform I found that my Distributed Switch was still at Version 5.1.0


I upgraded it to Version 5.5.0 and attempted to create the Unicast Transport zone again…this time with success. In discussions with @pandom_ What the documentation doesn’t specify (that we could find) is that you absolutely require your Distributed Switch to be version 5.5. Some people may call that an obvious oversight, but when coming from an established and potentially mixed environment that’s been upgraded it’s something to be aware of. As long as all your member Hosts are 5.5 you can upgrade the dvS.

A Multicast Transport zone remains an option to help deal with legacy VXLAN deployments such as the ones configured with vCNS and vCloud 5.x. In my case the end result was two Transport Zones…one configured with Unicast, and one with Multicast.


Now the fun begins!