VMware vSphere has a set of virtual networking elements that lets you network the virtual machines in the datacenter like physical machines are networked in a physical environment.

The virtual environment provides networking elements similar to those in the physical environment. They are virtual network interface cards (virtual NICs), vSphere Distributed Switches (VDS), distributed port groups, vSphere Standard Switches (VSS), and port groups.

Each virtual machine has one or more virtual NICs. The guest operating system and application programs communicate with a virtual NIC through either a commonly available device driver or a VMware device driver optimized for the virtual environment. In either case, communication in the guest operating system occurs just as it would with a physical device. Outside the virtual machine, the virtual NIC has its own MAC address and one or more IP addresses. It responds to the standard Ethernet protocol as would a physical NIC. An outside agent does not detect that it is communicating with a virtual machine.

A virtual switch works like a layer 2 physical switch. With vSphere Standard Switch, each server has its own virtual switches. With vSphere Distributed Switch, a single virtual switch spans many servers. On one side of the virtual switch are port groups that connect to virtual machines. On the other side are uplink connections to physical Ethernet adapters on the servers. Virtual machines connect to the physical environment through the physical Ethernet adapters that are connected to the virtual switch uplinks.

A virtual switch can connect its uplinks to more than one physical Ethernet adapter to enable NIC teaming. With NIC teaming, two or more physical adapters can be used to share the traffic load or provide passive failover if a physical adapter hardware fails or a network outage occurs.

A port group is a unique concept in the virtual environment. A port group is a mechanism for setting policies that govern the network connected to it. For VDS, the groups are called distributed port groups. A virtual switch can have multiple port groups. Instead of connecting to a particular port on the virtual switch, a virtual machine connects its virtual NIC to a port group. Virtual machines that connect to the same port group belong to the same network inside the virtual environment even if they are on different physical servers.

You can configure port groups to enforce policies that provide enhanced networking security, network segmentation, better performance, high availability, and traffic management.

A vSphere Distributed Switch (VDS) functions as a single virtual switch across all associated hosts. This ability allows virtual machines to maintain consistent network configuration as they migrate across multiple hosts. Each VDS is a network hub that virtual machines can use. A VDS can route traffic internally between virtual machines or link to an external network by connecting to physical Ethernet adapters. Each VDS can also have one or more distributed port groups assigned to it. Distributed port groups aggregate multiple ports under a common configuration and provide a stable anchor point for virtual machines connecting to labeled networks.

Relationship Between the Networks with vSphere Distributed Switches Inside and Outside the Virtual Environment
Represents networking with vNetwork Distributed switches and shows the relationshop between networks inside and outside of the virtual environment are represented.

Network resource pools determine the priority that different network traffic types are given on a VDS. When network resource management is enabled, VDS traffic is divided into the following network resource pools: FT traffic, iSCSI traffic, vMotion traffic, management traffic, NFS traffic, and virtual machine traffic. You can control the priority for the traffic from each of these network resource pools by setting the physical adapter shares and host limits for each network resource pool.

The VMware virtual switching layer provides a set of features similar to traditional physical switches, like VLANs, traffic shaping, and monitoring.

With vSphere Standard Switches, each server has its own virtual switch: VSSs handle network traffic at the host level in a vSphere environment. A VSS can route traffic internally between virtual machines and link to external networks.

Relationship Between the Networks with vSphere Standard Switches, Inside and Outside the Virtual Environment
Represents networking with vNetwork standard switches and shows the relationship between networks inside and outside of the virtual environment.

See the vSphere Networking documentation.