The virtual machine networking settings in Virtual PC 2004 (833134)

SUMMARY

This article describes the networking settings that are available for each virtual machine in Microsoft Virtual PC 2004.

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Manage network adapter settings for virtual machines

The Networking settings control whether network adapters are available for the virtual machine. By default, one network adapter is selected and mapped to the network adapter in the physical computer. If you want a virtual machine to use resources on a physical network, including your intranet and the Internet, you must configure the Networking settings of the virtual machine. To do so, follow these steps:

In the Virtual PC console, click the virtual machine where you want to configure the networking setting, and then click Settings.
Under Settings, click Networking.
Under Networking, configure the options that you want to use for the network adapters:
- In the Number of network adapters drop-down list, specify up to four emulated network adapters for the virtual machine.
- A set of configuration drop-down lists appear, depending on how many emulated network adapters that you selected in the Number of network adapters drop-down list. In these drop-down lists, assign each emulated adapter card to any network card that is installed on the physical computer, including Microsoft Loopback Adapter. You can assign more than one emulated network card to the same network card in the physical computer. Alternatively, you can attach a virtual network to a local-only network. A local-only network is a private network for communication between virtual machines only.
Click OK.

The following table describes the adapter options that appear in the drop-down list.

Option	Description
Not connected	With this option, networking is not available in the virtual machine. It is a good idea to select this option when the physical computer is not on a network, or if you do not access the Internet through a virtual machine. This option can prevent possible delays if the virtual machine software checks the network controller.
Local only	This option gives you networking support between virtual machines only. Therefore, the virtual machine does not have access to any network resources on the host operating system.
Shared Networking (NAT)	You can assign the first virtual machine network card to Shared Network (NAT). With this option, the virtual machine connects to a private network that Virtual PC creates. The network includes a virtual DHCP server and a virtual network address translation server. The virtual machine can access most TCP/IP-based resources that the host operating system can access. For more information about shared networking, see the "Manage shared networking for virtual machines" section of this article.
Network adapter on the physical computer	With this option, the virtual machine connects directly to the currently selected network connection of the host operating system. The virtual machine appears and behaves like a separate physical computer on the same network. The configuration of the network determines the networking configuration of the virtual machine. For example, the configuration of the network determines how an IP address is assigned to the virtual machine. If the network uses a DHCP server, an IP address is assigned dynamically to the virtual machine. Similarly, if the network uses static IP addresses, you must manually configure the virtual machine to use a static IP address. To do so, use the method that is specified in the documentation for the virtual machine operating system.
Microsoft Loopback Adapter	If you want to create a more complex network environment on a single physical computer, and you do not want to install multiple physical network cards, you can install multiple instances of Microsoft Loopback Adapter on the host operating system. For more information about Microsoft Loopback Adapter, see the "Extend networking capabilities for virtual machines" section of this article.

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Manage shared networking for virtual machines

With shared networking, a virtual machine can access the TCP/IP-based resources that are available on the host operating system. Virtual PC acts as the DHCP server and assigns a dynamic IP address to each virtual machine that uses shared networking. The IP address is in the 192.168.131.x range, and individual virtual machines are assigned a value for x from 1 to 253. Virtual PC does not provide an interface to manually specify the dynamic IP address that the virtual DHCP server assigns. If the host operating system is configured to use an address in the 192.168.131.x range, you must change the configuration of the host operating system. To use shared networking, you must configure the operating system that is installed on the virtual machine to automatically obtain an IP address from a DHCP server. For more information, see the documentation for the virtual machine operating system.

A virtual machine that is configured to use shared networking behaves like a computer behind a Network Address Translation (NAT) router. Shared networking does not support inbound port mapping. External computers cannot access a server that is running in the virtual machine or any ports on the virtual machine. Shared networking also does not support networking between virtual machines or from the host operating system to the virtual machine.

For more information about networking, see the "Manage network adapter settings for virtual machines" section of this article.

Notes

When you use shared networking, the virtual machine shares the Internet connection that is set up on the host operating system, regardless of whether the host is connected through a modem or through a local area network (LAN).
Some networking software, such as chat programs, may not work correctly under shared networking because some networking software requires a static IP address.
Users who are not administrators or members of the administrators group on the host operating system cannot send or receive pings or other Internet Control Message Protocol (ICMP)-based network traffic when shared networking is activated.

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Extend networking capabilities for virtual machines

You can install and configure Microsoft Loopback Adapter to extend the networking capabilities for virtual machines. Microsoft Loopback Adapter gives you the following networking capabilities:

You can have networking for virtual machines when the host operating system does not have a physical network connection available. To provide network connectivity between the host and the virtual machines, install Microsoft Loopback Adapter on the host operating system, and then configure a network connection on each virtual machine and the host operating system.
You can set up a complex virtual network environment with multiple routers and firewalls. To provide multiple network solutions for virtual machines, install Microsoft Loopback Adapter on the host operating system, and then set up as many network connections on each operating system as you want.

Important If you want to access the Internet from a virtual machine that is configured to use the Microsoft Loopback Adapter, you must enable Internet Connection Sharing on the host computer. For more information about Internet Connection Sharing, see the documentation that is included with the version of Windows that is installed on the host computer.

To Set up a virtual network connection, you must install Microsoft Loopback Adapter, and then configure the network connection for the adapter. When you configure the Microsoft Loopback Adapter, you must also configure TCP/IP on the network connection to use an appropriate IP address.

You can use any TCP/IP address, but it is best to select an address from a reserved range of private TCP/IP addresses. For example, TCP/IP addresses that have the form 192.168.x.y, where x is a value between 0 and 255, and where y is a value between 1 and 254, are private. The value that you select for x must be the same on the host operating system and on each guest operating system that you want as part of the virtual network. If your primary Ethernet connection uses one of these private addresses, you must select a different value for x to assign to Microsoft Loopback Adapter.

For information about how to set up Microsoft Loopback Adapter for a host operating system that is running Microsoft Windows XP or Microsoft Windows 2000, see the Virtual PC Help topic, "Install and configure Microsoft Loopback Adapter." For information about how to install Microsoft Loopback Adapter on other operating systems, see the documentation for the operating system.

For more information about networking, see the "Manage network adapter settings for virtual machines" section of this article.

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Manage shared folders for virtual machines

With shared folders, a virtual machine can use a folder or a volume on the host computer as if it were a network share. A shared folder can be persistent or temporary. A persistent shared folder is shared again every time the guest operating system starts. A temporary shared folder is only available until the guest operating system is shut down. You cannot share folders directly between virtual machines, but multiple guest operating systems can share a folder on the host operating system.

Before you can use shared folders, you must configure the Shared Folders setting on the virtual machine. The Shared Folders setting is available only if the virtual machine is running and you have installed Virtual Machine Additions.

To share folders, use any one of the following methods:

In the Virtual PC window, click the virtual machine that you want to configure, click Settings , and then click Shared Folders in the Settings dialog box for the virtual machine.
Right-click the folder icon on the Status bar of the virtual machine, and then click Shared Folder Settings.
Drag a folder or volume to the folder icon.