Virtual machines connect on the same network and communicate with each other using a piece of software called a virtual switch. Virtual switches or vSwitches perform an essential role in modern virtualization. Namely, a vSwitch allows the connection between virtual and physical networks, essentially allowing traffic to flow from one virtual machine to another.
Virtual switches are important to virtual infrastructure, so much so that many hypervisors, such as VMware, rely on vSwitches for their VMware vSphere environment to run as intended. In addition, because many virtual infrastructures incorporate more than a single virtual machine, the only way for VMs to communicate and share traffic is through virtual switches.
This guide will explain the idea behind virtual switches and why they’re so important in modern virtualization. With that said, let’s start.
What Are VMware Virtual Switches? A Dive Into Virtual Networking
To understand virtual switches, we need to understand the concept of a virtual network. Every hypervisor has some way to connect a virtual network to a physical network. In VMware’s case, this is done through a host of virtual and physical components.
Some components, such as network adapters or NICs, are visible to the naked eye. Others are entirely virtual, meaning they don’t physically exist, much like a virtual machine. These components facilitate communication between a physical network and a virtual one. In addition, virtual networking allows communication between multiple virtual machines, ESXi servers, or other virtual devices.
Unlike a physical network, where you need cables to connect multiple physical computers, a virtual network does this through software. The biggest use case for a virtual network is to connect virtual machines to the Internet.
So, where do virtual switches come in all this? A virtual switch is similar to a physical switch in that it has the same functions and capabilities. The only difference is in the name itself. A virtual network is entirely none existent. Other vital components of a virtual network include network adapters and port groups.
How do VMware Virtual Switches work?
With the concept of virtual networking out the way, let’s look at how a VMware virtual switch works.
Virtual switches in VMware detect which virtual machines are connected to which virtual ports. Virtual ports or port groups provide an anchor point for virtual machines and virtual networks. The port group assigns the same tag to all of the connected virtual machines. One of the most common port group tags is the VLAN tag.
As mentioned previously, virtual switches and virtual machine network adapters are connected to virtual machines on the same network. The switches are the connection between a physical network and a virtual network. You can also connect vSwitches and virtual network adapters to a network interface card (physical NIC) to a physical network.
So virtual switches allow communication between virtual machines. A virtual machine port group passes traffic between the virtual machines, ensuring the traffic never leaves the virtual environment.
To summarize how virtual switches work:
- A physical network is connected to the virtual network using a virtual switch;
- The virtual switch connects with the network interface cards of virtual machines on a port group;
- Virtual switches provide an anchor point for the traffic of virtual machines on the same port group.
Remember once again that these components are virtual, i.e., nonexistent.
VMware vSwitches come with advanced port forwarding capabilities. For example, you can take a virtual switch port group and assign it to VLANs in your network. These enable, most commonly, a connection to the Internet.
Types of Virtual Switches in VMware
These are two types of virtual switches in VMware. Those are your standard virtual switch and distributed virtual switch. Both standard and distributed virtual switches tap into the virtual adapter’s MAC address to listen to traffic. In addition, both types of virtual switches use physical network adapters to connect with an ESXi host.
Let’s explain more about both types of virtual switches and the areas they excel at:
Standard Virtual Switch VSS
- Work similarly as a physical Ethernet switch;
- Provide network connectivity to virtual machines and ESXi hosts;
- Standard vSwitches allow traffic internally between VMs on the same VLAN with an external network;
- A Standard switch VSS detects which VM is connected to one of its virtual port groups and allows traffic to designated VMs;
- A standard switch works with only a single ESXi host.
Distributed Virtual Switch VDS
- Different hosts can use the switch, with the prerequisite that ESXi hosts are on the same host cluster;
- Simplifies the virtual network through features and extended ports for management across multiple port groups in servers on a cluster;
- Each vCenter Server supports up to 128 distributed virtual switches, while each disturbed virtual switch supports up to 500 hosts.
From this, we can conclude that standard switches work with only a single ESXi host, while a distributed switch works with multiple ESXi hosts. In addition, a vSphere distributed switch enables extra features that simplify the way port groups connect to virtual machines.
A Notable feature of VDS includes physical NIC load balancing.
Why Are Virtual Switches Important in VMware?
Now we come to the topic of this guide – why are vSwitches so important to your VMware virtual infrastructure? Here are the key talking points:
- Virtual switches allow us to manage them more effectively through the hypervisor;
- Setting up new virtual switches and creating additional functionalities for said vSwitches is seamless compared to physical switches;
- Virtual switches are more secure. You can set up new policies and determine unique security settings for each virtual switch;
- Makes testing possible in an isolated environment. A virtual switch can completely isolate a VM from the virtual network.
Virtual switches in VMware are core components of virtual networking. This guide offers a complete overview of virtual switches and their work in the VMware hypervisor. We hope this guide also covers all aspects of virtual switches, including what makes them important in VMware.