Starting NSX 3.2.2 release the Sub-Transport Node Profile within a Transport Node Profile feature was created in order to support Stretched L2/L3 clusters and stretched vSAN clusters
Sub-TNP is basically a template to be applied to Sub-Clusters to be prepared for NSX with a configuration different than the one used in one TNP , one use case is having ESXi hosts under the same clusters in different sites, however the host TEP network is not available/stretched across the two sites, in this case a Sub-TNP can be applied to the Sub-Clusters of the second site for instance with different host TEP which means different IP pools and a different VLAN, without affecting the overlay segment communication across the two stretched vSphere cluster.
A sub-TNP can only override the following fields of a host switch: VDS Host Switches ID, uplink profiles and IP assignment.
In this blog we’ll demonstrate that, I have a vSphere cluster with 2 ESXi hosts, esxi03 and esxi04, assuming that esxi04 is in a different site and the host TEP subnet used for esxi03 is not available at the second site, so we’ll create 2 different uplink profiles, 2 different IP Pools.
vSphere Cluster:
Network Pools:
The first pool will be referred to in the Transport Node Profile used for esxi03:
The second IP Pool will be referred to in the Sub-TNP used to prepare esxi04:
IP Pools
The first IP Pool will be referred to in the Transport Node Profile used for esxi03:
The second IP Pool will be referred to in the Sub-TNP used for esxi04:
We’ll create a Sub-Cluster and add to it esxi04:
You’ll notice here that the sub-cluster was added for esxi04
Transport Node Profile:
Notice here the uplink profile and host TEP IP pool used are for esxi03
However in the Sub-TNP the below configuration was used:
Next step, is to prepare the cluster using the TNP and the Sub-TNP:
Notice here that the we are applying the Sub-TNP to the Sub-Cluster
Let’s check the host TEPs assigned to esxi03
Let’s check the host TEPs assigned to esxi04
Testing TEP to TEP reachability
So to conclude, it’s a nice feature to have, in case of underlay networking restrictions.
References:
The SDN Blog 