What is N-VDS or hostSwitch in NSX-T?

The NSX managed virtual distributed switch (N-VDS, previously known as hostswitch) or OVS is invisible to the tenant network administrator and provides the underlying forwarding. The primary component involved in the data plane of the transport nodes is the N-VDS. The N-VDS forwards traffic between components running on the transport node (e.g., between virtual
machines) or between internal components and the physical network. While configuring the hypervisor hosts or the NSX-T edges as Transport node, the admin must specify the Transport Zone, Uplink Profile and Physical Network adapters(pNICs). The N-VDS must own one or more physical interfaces (pNICs) on the transport node. The physical network adapters owned by the N-VDS cannot be shared with any another N-VDS. The N-VDS can coest with vSwitch, dvSwitch, another N-VDS when using a separate set of pNICs.

N-VDS implementation on ESXi and KVM:

On ESXi hypervisors, the N-VDS implementation is derived from VMware vSphere® Distributed Switch™ (VDS) through the nsx-vSwitch module. The nsx-vswitch module is loaded in to the kernel when the hypervisor host is configured as a Fabric Node. The N-VDS is a mandatory component for running the Overly network can coexists with the vSwitch, DVSwitch as long as they are configured with a different set of pNICs. The nsxa agent/process running on the ESXi host will configure the hostswitch with the help of the nsx-vswitch kernel module.

Run the following command to list the NSX Kernel modules on the ESXi host.

[root@esx-04a:~] esxcfg-module -l | grep nsx

To list the packages installed on the ESXi host, run the following command:

[root@esx-04a:~] esxcli software vib list | grep nsx

On KVM hypervisor, the Open-vSwitch (OVS) module implements the Hostswitch. You may run the following command to check the list of the opevSwitch packages installed on the Ubuntu KVM host.

root@kvm-01a:~# dpkg -l | grep openvswitch-*

List of packages installed on KVM, pushed from the NSX Manager are :

Conclusion:

In this blog post, we have discussed the following:

What is N-VDS or hostswitch?
How is the ESXi implements the N-VDs?
How is the KVM implements the N-VDs?
Packages installed on ESXi/KVM hosts?

For more information about the N-VDS, please do read the NSX-T Documentation:

I hope this is informative for you and thank you for reading.

10 Responses

How to create a Transport Node in NSX-T • Virtual Brigade July 8, 2018 at 2:49 pm | Permalink

[…] What is N-VDS or hostSwitch in NSX-T? […]

Arunabha Ghosh July 9, 2018 at 10:00 am | Permalink

What if a standalone ESXi is being managed by NSX-T manager as it is vCenter independant, then how the N-VDS aka “hostswitch” will derive from? Is that Standard switch?

CHAND BASHA SHAIK July 10, 2018 at 10:04 pm | Permalink

The NSX-T Data Center is designed to be a completely independent of the vCenter Server environment.
To implement a hostswitch on a standalone ESXi host, the NSX-T Manager leverages the nsx-vswitch module installed on the ESXi host.
The nsx-vswitch module is installed When the ESXi host is configured as a Fabric node. While configuring the ESXi as a transport node, the NSX-T host switch gets created with the nsx-vswitch module.
The nsx-vswitch is forked from the etherswitch switch module.
You can execute the following command to list the nsx vibs installed on the ESXi host:

[root@esx-04a:~] esxcli software vib list | grep nsx
nsx-aggservice
nsx-common-libs
nsx-ctxteng
nsx-da
nsx-esx-datapath
nsx-exporter
nsx-host
nsx-hyperbus
nsx-lldp
nsx-metrics-libs
nsx-mpa
nsx-nestdb-libs
nsx-nestdb
nsx-netcpa
nsx-platform-client
nsx-python-protobuf
nsx-rpc-libs
nsx-sfhc
nsx-shared-libs
nsx-support-bundle-client
nsxa
nsxcli

To list the modules, run the following command:
[root@esx-04a:~] esxcfg-module -l | grep nsx
nsx-core 11 16
nsx-traceflow 4 20
nsx-fc 5 516
nsx-vswitch 15 304
nsx-bfd 7 24
nsx-switch-security 5 84
nsx-kcp 4 172
nsx-ipfix 0 60
nsx-vdl2 6 548
nsx-vdrb 1 436
nsx-vsip 20 648
nsx-dne 10 188

On the KVM hypervisors, the nsx-t manager leverages OVS to implement the hostswitch

Reply