Enhancements to Microsoft Peer-to-Peer Networking when you upgrade to Windows XP Service Pack 2 or to Windows XP Tablet PC Edition 2005

When you use the Advanced Networking Pack for Windows XP in an enterprise environment, and a user roams with a portable computer between home and work, peer-to-peer programs may not work correctly. Additionally, administrators do not have a way to turn off the various Microsoft peer-to-peer protocols.

This problem occurs because of a limitation in the way that protocol settings are configured in the initial implementation of the Advanced Networking Pack for Windows XP Service Pack 1 (SP1).

To resolve this problem, you must install Windows XP SP2.

Note The Windows XP SP2 features and components are included in Windows XP Tablet PC Edition 2005.

This service pack provides for policy-based configuration of certain aspects of peer networking protocols. The Peer Name Resolution Protocol (PNRP) permits distributed resolution of a name to an IP version 6 (IPv6) address and port number. The protocol operates in the context of clouds. A cloud is a set of peer computers that can communicate with each other by using the same IPv6 scope. There are three types of clouds, as follows:

• Global
  Global addresses are used across the Internet. If a computer is connected to the Internet, the computer is part of a global cloud.
• Site-local
  Site-local addresses are used on a single site for a group of computers or networks that are not on the Internet.
• Link-local
  A link-local address is used when a computer has not yet acquired addresses of a larger scope.

PNRP must be bootstrapped before it can participate in a cloud. Bootstrapping occurs in the following way:

1. If the computer has participated in a peer-to-peer cloud previously, the protocol uses cached information to bootstrap itself.
2. If step 1 does not work, the computer sends a local Simple Service Discovery Protocol (SSDP) multicast message on the subnet to see if other online computers are available to help bootstrap the protocol.
3. If step 2 does not work, the computer sends a message to a well-known node that is hosted on the Internet. (This node is also known as a seed server.) Alternatively, the computer can be configured to point to a node in the corporation by using Group Policy settings.

With the initial implementation of the Advanced Networking Pack for Windows XP, you could not configure the seed server by using Group Policy settings. Therefore, peer-to-peer programs would not work if a mobile user took a portable computer and used it both at home and at work. The following policies have been introduced to help with the problems that are mentioned in the "Symptoms" section and to let you centrally manage peer-to-peer networking services.

Group Policy object (GPO) settings to manage Microsoft Peer-to-Peer Networking Services

Turn off Microsoft Peer-to-Peer Networking Services

The Turn off Microsoft Peer-to-Peer Networking Services setting is located in the following Group Policy Object Editor path: This setting turns off Microsoft Peer-to-Peer Networking Services and causes all dependent programs to stop working. Peer-to-peer protocols enable programs in the areas of Real-time Communications (RTC), collaboration, content distribution, and distributed processing. If you enable this setting, peer-to-peer protocols will be turned off. If you disable this setting, or do not configure it, the peer-to-peer protocols will be turned on.

If this setting is disabled and subsequently enabled, you must restart dependent programs.

Set the Seed Server

Note This policy can be applied per cloud type.


The Set the Seed Server settings are located in the following Group Policy Object Editor paths:In the global cloud, you can use this setting to configure the seed server so that mobile users can use their peer-to-peer applications from home and from work. To do this, enable the policy setting and set it to an IPv6 address or to a DNS name of a corporate seed server. By default, peer-to-peer programs can roam between home and work. You can turn off this policy by clicking Disable for the appropriate cloud type policy.

In the site-local cloud or the link-local cloud, an enterprise administrator can specify the name of the corporate seed server for the global cloud. Because DNS will not be present in link-local clouds, specify only IPv6 addresses for that particular scope.

If the setting is not configured, the well-known seed server (pnrp.ipv6.microsoft.com) will always be used. This configuration could cause programs to work incorrectly in the enterprise.

Turn off Multicast Bootstrap

Note This policy can be applied per cloud type.

The Turn off Multicast Bootstrap setting is located in the following Group Policy Object Editor path: This setting keeps the PNRP protocol from advertising the computer or from searching other computers on the local subnet in the specific cloud. If you enable this setting, PNRP will not use multicast messages for bootstrapping. Setting this policy will break scenarios where there is no seed server for bootstrapping, such as in an ad hoc network scenario.

If you disable this setting, PNRP will use multicast messages for bootstrapping on the same subnet. If this setting is not configured, the protocol will revert to using a public registry key to determine whether the protocol will publish the computer or will use multicast to search for other computers on the local subnet.

The SSDP multicast protocol is used for bootstrapping. By default, the SSDP service is enabled. The service must be enabled for this policy to work.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.