Virtual Networks
A virtual network is a software emulation of a network hub with unlimited ports and a switched uplink that can connect to an external physical network through a physical network adapter or remain disconnected to create an isolated internal network. Each virtual network port simulates a 10/100 MB Ethernet port. Virtual Server 2005 R2 supports an unlimited number of virtual networks with an unlimited number of virtual machine connections.
By default, Virtual Server 2005 R2 creates a virtual network designated as Internal Network. The Internal Network supports virtual machine to virtual machine connectivity, ensuring that communications between virtual machines are isolated from any physical network. Network packets transmitted through the Internal Network are never processed by a physical network adapter, nor forwarded to any external physical network.
In addition, Virtual Server 2005 R2 automatically creates a virtual network designated External Network for each physical network adapter installed in the physical server. If a virtual machine is connected to one of these virtual networks, it will appear identical to a networked, standalone physical node and will have the ability to communicate with physical or virtual machine nodes across the networks accessible to the physical network adapter.
Virtual Server 2005 R2 also includes a Virtual DHCP server that can be enabled or disabled on each individual virtual network. If enabled on a virtual network, the Virtual DHCP server provides standard network configuration settings to virtual machines connected to the virtual network.
An isolated internal network can be created to enable network communications between a Virtual Server 2005 R2 host and guest virtual machines. This configuration requires the installation of the Microsoft Loopback Adapter.
Both internal and external virtual networks can be created through the Virtual Server 2005 R2 Administration website or using the Virtual Server COM API.
Virtual Network Adapters
Virtual machines emulate a virtual Multiport DEC 21140 network adapter to connect to virtual networks. When a virtual network adapter is added to a virtual machine, Virtual Server 2005 R2 allocates a new dynamic media access control (MAC) address from the pool of available addresses. It is also possible to provide a virtual network adapter with a static MAC address that is manually configured.
Virtual machines support a maximum of four virtual network adapters. Virtual network adapters support the Pre-boot Execution Environment protocol (PXE), allowing virtual machines to be provisioned using standard image deployment tools like Remote Installation Services, Automated Deployment Services, or other third-party applications. However, virtual network adapters do not provide support for either Virtual Local Area Networks (VLAN) or network interface card teaming.
Although the Dec 21140 network adapter defines a 10/100 Mb Ethernet interface, there is no network bandwidth limitation imposed on virtual machine workloads. If the underlying physical network adapter is capable of achieving higher network performance (i.e., Gigabit speed), then the virtual machine workload has the ability to exceed the 100Mb specification.
Technorati tags: Microsoft Virtual Server, Microsoft Loopback Adaptor, Virtualization, Virtual, Virtual Network, Virtual Machine
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