Deploying NSX-T in a Stretched Cluster – Part 1

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A stretched cluster architecture facilitates for higher levels of availability and things like inter-site load balancing. It’s a common multisite solution and also part of VMware’s Validated Design for SDDCs with multiple availability zones.

Traditionally compute networking in an active-active multisite setup has had its challenges, but with vSAN storage and NSX networking technologies that’s a thing of the past.

In the coming two articles I want to have a closer look at NSX-T in an active-active multisite environment. Specifically I want to learn more about how the different NSX-T components are deployed and how the data plane is configured in a stretched cluster.

In this first part I will deploy the NSX-T 2.5 platform and perform the necessary configurations and preparations so that in part two I can focus solely on the data plane (north-south and east-west).

This is going to be quite an exercise so let’s get right to it!

The lab environment

Below a high level overview of the lab environment as it looks right now:

lab environment

A vSAN cluster consisting of eight ESXi hosts stretched to a second site. A third site is hosting the vSAN witness appliance. A completely separate vSphere management cluster is only hosting the vCenter server right now.

A quick look at the vSphere environment then. I’m running vSphere 6.7 U3:


The hosts have two physical 10Gbit NICs:

physical nics

Three vmkernel adapters have been configured: Management, vMotion, and vSAN:

vmkernel adapters

As mentioned, this is a vSAN stretched cluster:

vsan stretched cluster

The following tables list the VLANs and the associated IP subnets that are currently configured per site:

Site A:

VLAN FunctionVLAN IDSubnetGateway
ESXi Management1641172.16.41.0/24172.16.41.253

Site B:

VLAN FunctionVLAN IDSubnetGateway
ESXi Management1651172.16.51.0/24172.16.51.253

Witness Site:

VLAN FunctionVLAN IDSubnetGateway
ESXi Management1711172.17.11.0/24172.17.11.253

Management Cluster:

VLAN FunctionVLAN IDSubnetGateway
SDDC Management1611172.16.11.0/24172.16.11.253

NSX-T is not deployed yet, but that’s about to change pretty soon 😉

Deploying the NSX-T manager cluster

Installing NSX-T 2.5 always starts with deploying the manager cluster. It consists of three manager nodes and an optional virtual IP (VIP).

I will deploy the NSX manager cluster nodes in the vSphere management cluster and connect them to the SDDC Management VLAN (1611).

The IP plan for the NSX manager cluster looks like this:

HostnameIP Address
nsxmanager172.16.11.81 (virtual IP)

First manager node

I deploy the first manager node from the OVA package:

first nsx manager node

Filling out the configuration details and then kicking off the deployment.

When the first manager node is up and running I’m logging in to the NSX Manager UI:

first nsx manager ui login

Second and third manager nodes

The second and third manager nodes can be deployed from the NSX Manager UI. Before I can do that I need to add my vCenter server under System > Fabric > Compute Manager:

compute manager added

Now I’m able to deploy the second and third manager nodes via System > Appliances > Add Nodes.

Once done the three nodes are shown in the UI and the cluster connectivity is up:

three nodes deployed

Assign virtual IP address

I finalize the manager cluster deployment by configuring a virtual IP address. This is done under System > Appliances > Virtual IP:

change vip

A couple of minutes later the virtual IP is active:

vip configured

Configuring the NSX-T data plane

Now that the NSX-T management plane is fully operational I will continue with the data plane preparations and configurations.

More VLANs

First I need to provision some more VLANs in the TORs at the data sites. At each site I need two VLANs for overlay and another two for connecting NSX with the physical network later on:

Site A:

VLAN FunctionVLAN IDSubnetGateway
Host overlay1644172.16.44.0/24172.16.44.253
Edge overlay1649172.16.49.0/24172.16.49.253

Site B:

VLAN FunctionVLAN IDSubnetGateway
Host overlay1654172.16.54.0/24172.16.54.253
Edge overlay1659172.16.59.0/24172.16.59.253

Transport zones

Two transport zones should do it I believe. I create them using the following details:

NameN-VDS NameTraffic Type

Transport zones are managed under System > Fabric > Transport Zones:

transport zones

Uplink profiles

Next, I need to create four uplink profiles. The table below shows the configuration details for each of them:

NameTeaming PolicyActive UplinksTransport VLANMTU
up-site-a-esxiLoad Balance Sourceuplink-1, uplink-2 16449000
up-site-a-edgeLoad Balance Sourceuplink-1, uplink-2 16499000
up-site-b-esxiLoad Balance Sourceuplink-1, uplink-2 16549000
up-site-b-edgeLoad Balance Sourceuplink-1, uplink-2 16599000

Uplink profiles are managed under System > Fabric > Profiles > Uplink Profiles:

uplink profiles

In order to achieve VLAN pinning, deterministic routing, and ECMP I need to add two named teaming policies to the uplink profiles that I just created:

NameTeaming PolicyActive Uplinks
Uplink01Failover Orderuplink-1
Uplink02Failover Orderuplink-2

Adding the named teaming policies to the uplink profiles:

add named teaming policies

I also need to add the Uplink01 and Uplink02 named teaming policies to transport zone tz-vlan. This so that they can be selected on segments belonging to that transport zone later on:

named teaming policies to transport zone.

Network I/O Control profile

To allocate bandwidth to different types of network traffic I create a network I/O control profile. After long and hard thinking I decided to call it nioc-profile and it has the following settings:

Traffic Type / Traffic NameShares
Fault Tolerance (FT) Traffic25
vSphere Replication (VR) Traffic25
iSCSI Traffic25
Management Traffic50
NFS Traffic25
vSphere Data Protection Backup Traffic 25
Virtual Machine Traffic100
vMotion Traffic 25
vSAN Traffic 100

Network I/O control profiles are managed under System > Fabric > Profiles > NIOC Profiles:

nioc profile


VLAN-backed segments are needed for system, uplink/transit, and overlay traffic. The table below lists the segments with their settings that I will create:

Segment NameUplink & TypeTransport ZoneVLAN

Segments are managed under Networking > Connectivity > Segments:

vlan-backed segments

Uplink teaming policy

The uplink teaming policy for segments edge-uplink1 and edge-uplink2 need to be modified so that the named teaming policies Uplink01 and Uplink02 are used instead of the default.

For this I have to edit these segments under Advanced Networking & Security > Networking > Switching:

change segment teaming

Configure ESXi hosts

Now the time has come to configure the ESXi hosts and turn them into NSX-T transport nodes!

In the NSX Manager UI I navigate to System > Fabric > Nodes and change the “Managed by” to my vCenter server. The ESXi hosts are listed:

unconfigured hosts

Unfortunately, I can’t make use of a transport node profiles here as these are assigned at the vSphere cluster level. I will therefore configure my hosts one at a time.

The ESXi transport nodes in Site A will be configured with the following settings:

Transport Zonetz-vlan, tz-overlay
N-VDS Namenvds01
NIOC Profilenioc-profile
Uplink Profileup-site-a-esxi
LLDP ProfileLLDP [Send Packet Disabled]
IP AssignmentUse DHCP
Physical NICSvmnic0 – uplink-1
vmnic1 – uplink-2

ESXi transport nodes in Site B use slightly different settings:

Transport Zonetz-vlan, tz-overlay
N-VDS Namenvds01
NIOC Profilenioc-profile
Uplink Profileup-site-b-esxi
LLDP ProfileLLDP [Send Packet Disabled]
IP AssignmentUse DHCP
Physical NICSvmnic0 – uplink-1
vmnic1 – uplink-2

Selecting one host at a time clicking Configure NSX:

configure nsx

The network mappings for install for vmkernel adapter migration:

network mappings for install

When I click Finish the NSX installation and configuration process starts on the selected ESXi host. NSX bits are installed, the host receives the N-VDS, and the vmkernel adapters are migrated from VDS port groups to the N-VDS segments.

When all hosts have been configured I quickly check the status of the transport nodes:

transport node status

And in vCenter I notice there’s now an N-VDS with a bunch of opaque port groups:

n-vds installed


Most of the NSX-T platform is in place now and I think this is a good point to take a small break.

I started by deploying and configuring the NSX manager cluster (aka the central management plane). Next, I prepared the environment for the NSX data plane by provisioning some VLANs, profiles, and segments. Lastly, I prepared the ESXi hosts in the stretched cluster by installing the NSX VIBs and configuring them as NSX transport nodes. vSphere system networking (vmkernel adapters) was migrated to the N-VDS.

In the next part I will continue with the installation of the data plane and more specifically deployment and configuration of the NSX Edge as well as the logical networking components.

Stay tuned!


  1. Hi,
    nice post.
    About security aspects, which is the correct way to insert a E-W traffic inspection in this environment?
    can you suggest some about integration with 3 part integration such as Cloud Guard IaaS Check Point ?


    1. Thanks Luca!

      For specifics about 3rd part integration please check the vendor’s documentation.

      From a NSX-T perspective, E-W service insertion is always done in the same way. So either on-host with the vendor appliance on each host, or using the service cluster where traffic is steered to a central cluster with the vendor’s solution.

      In the stretched environment I would probably look at doing it on-host, but as always it will depend on your requirements and specifics of the environment.

      Here’s a pretty nice VMworld 2019 session about Check Point’s integration with NSX-T :



  2. I’m trying this exact same setup with newer versions. I’m getting a configuration mismatch error. Any chance you saw the same and worked around it? I’m using 3.1 and VC 7.0.2 with VDS instead of N-VDS.


  3. I’m trying the exact same thing with later versions and my prepped hosts are showing as mismatched. Did you see this at all? I’m using 3.1/7.0.2 with VDS instead of N-VDS.


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