In the previous post, we discussed about vSphere Standard Switches. Though standard switches are simple and easy to configure/manage, there are certain limitations of using standard switches in a large environment, like no centralized management, no support for NIOC, no backup and restore capability, etc. With the vSphere Standard Switch, we have to configure and maintain each standard switch individually across each ESXi host since the VSS contains both the data and management plane functionality with each VSS switch configuration.
To address many of the standard switch limitations, the vDS separates the networking data plane from the control plane enabling the advance features like load balancing, centralized management, and so on.
The data plane allows the VDS to perform packet switching, filtering, VLAN tagging, etc, while the management plane controls the data plane in a centralized manner. The management plane is centralized with VMware vCenter Server. This means instead of creating the vDS at each ESXi host in the cluster, it is created at the vCenter Server level once. Post which we can simply choose which ESXi hosts to associate with the vSphere Distributed Switch. This is a much simpler and much more efficient process for provisioning virtual networking across vSphere environment.
An important point to note here is vSphere Standard Switches are available by default with any license level. However, the vSphere Distributed Switch is a feature that is only available at the Enterprise Plus license level for vSphere.
(Image Courtesy - VMware)
Above diagram shows vDS architecture and how the management plane is kept separate from the data plane. The management plane resides on the vCenter Server while the data plane, also referred to as a host proxy switch, is local to the ESXi host. This is the primary reason why vCenter Server needs to be installed if we have to configure the distributed switch.
In addition to centralized management, VMware vDS provides below features -
Network I/O Control - Inbound traffic shaping, bandwidth reservations.
Port mirroring - Allows you to send copies of frames detected on some port of a virtual switch to a specified port of another switch for monitoring, traffic analyzing, and debugging.
Private VLANs – Use of Private VLANs can help increase the number of available VLANs as well as bolster security
Network health check - Configuration such as VLAN settings, MTU, NIC teaming are checked every minute by default.
Network vMotion - Preserves the connection of a VM virtual network adapter to the same port of the VMware distributed switch.
Backup and restoring network configuration.
The vSphere Distributed Switch introduces two abstractions
Uplink port group
An uplink port group or dvuplink port group is defined during the creation of the distributed switch and can have one or more uplinks. An uplink is a template that you use to configure physical connections of hosts as well as failover and load balancing policies. You map physical NICs of hosts to uplinks on the distributed switch. At the host level, each physical NIC is connected to an uplink port with a particular ID. You set failover and load balancing policies over uplinks and the policies are automatically propagated to the host proxy switches, or the data plane. In this way you can apply consistent failover and load balancing configuration for the physical NICs of all hosts that are associated with the distributed switch.
Distributed port group
Distributed port groups provide network connectivity to virtual machines and accommodate VMkernel traffic. You identify each distributed port group by using a network label, which must be unique to the current data center. You configure NIC teaming, failover, load balancing, VLAN, security, traffic shaping , and other policies on distributed port groups. The virtual ports that are connected to a distributed port group share the same properties that are configured to the distributed port group. As with uplink port groups, the configuration that you set on distributed port groups on vCenter Server (the management plane) is automatically propagated to all hosts on the distributed switch through their host proxy switches (the data plane). In this way you can configure a group of virtual machines to share the same networking configuration by associating the virtual machines to the same distributed port group.
Let's see how to Create a Distributed Switch
Once you are login to the vCenter, navigate to the Networking View.
Right Click on the datacenter > Distributed Switch > New Distributed Switch
Give a name to distributed switch
Select an appropriate version as per your requirement
Configure the port group settings
Number of Uplinks
Uplink ports connect the distributed switch to physical NICs on associated hosts. The number of uplink ports is the maximum number of allowed physical connections to the distributed switch per host.
Network I/O Control
By using Network I/O Control you can prioritize the access to network resources for certain types of infrastructure and workload traffic according to the requirements of your deployment. Network I/O Control continuously monitors the I/O load over the network and dynamically allocates available resources.
Select the Create a default port group check box to create a new distributed port group with default settings for this switch
To create a default distributed port group, type the port group name in the Port group name, or accept the generated name.
Review the settings and click on FINISH.
So far we have just created an empty distributed switch. The next step is to add the ESXi hosts to a distributed switch. We will discuss more about Distributed switch settings later.
In this post, we learned about the basics of distributed switching with a short explanation on distributed port groups, uplinks and how to create vDS. As mentioned this is just a small piece of information which should suffice to get you started with vSphere networking.
For more information refer to the vSphere Networking guide from VMware.
I hope you've enjoyed reading this post and find this useful.
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