VMware vSphere provides four types of network virtualization services to hosts and virtual machines. The platform links virtual machines to each other within a single host, connects virtual machines to the physical network and also joins VMkernel services (such as NFS, iSCSI and VMware vSphere vMotion) to the physical network. Lastly, it provides networking for the management interface, which runs management services for vSphere hosts.
The vSphere platform has two logical networking building blocks: virtual Ethernet adapters and virtual switches.
About Virtual Networking
Virtual Ethernet Adapters
Configure virtual machines with one or more virtual Ethernet adapters, presented to the guest OS by the virtual machine hardware. The guest OS sees virtual adapters as common network interface cards and will use standard drivers. Several special-purpose virtual Ethernet adapters are also available to deliver optimized performance in a virtual machine environment, with corresponding OS drivers provided as a part of VMtools.
Virtual switches allow virtual machines on one vSphere host to communicate with each other using the same protocols as physical switches. The virtual switch emulates a traditional physical Ethernet network switch by forwarding frames at the data-link layer. A vSphere host can have numerous virtual switches, each with more than 1,000 internal virtual ports for virtual machines.
The vSphere platform supports the vSphere Standard Switch, a virtual switch configuration at the host level, and the VMware vSphere Distributed Switch, a single virtual switch that spans multiple associated hosts.
Network I/O Control (NIOC)
VMware vSphere Network I/O Control lets you set up rules and policies for each virtual machine to ensure business-critical applications get priority network access. NIOC continuously monitors network load and, when congestion is detected, it dynamically allocates the available resources to your most important applications, improving and safeguarding their service levels.
The vSphere Distributed Switch (VDS) simplifies virtual machine networking by letting you set up virtual machine access switching for your entire data center from a centralized interface. This makes it easy to provision, administer and monitor virtual networking across multiple hosts and clusters. VDS also provides rich monitoring and troubleshooting capabilities, plus support for advanced vSphere networking features.