Can Applications Benefit From IPv6?

	Overview of Windows Meeting Space
	Windows Meeting Space and IPv6
	Barriers to IPv6 Deployment and Development?
	Conclusion
	For More Information

Overview of Windows Meeting Space

The Windows Meeting Space feature in Windows Vista simplifies common activities faced during business meetings, presentations, and collaborative sessions. The feature allows groups to instantly and securely form a shared, common session. Within this session, users can "project" their desktop or application to other participants or to a Windows Vista compliant network projector, share files with a group in a common work area and jointly edit the file, and pass notes to other session participants.

The following figure shows an example of using Windows Meeting Space to modify a presentation.

Windows Meeting Space operates entirely peer-to-peer, meaning that it can be used on any network, including corporate networks and public hotspots. Where connectivity is not available, the feature automatically creates an ad-hoc wireless network among the meeting participants.

Windows Meeting Space utilizes several services provided by the Windows Peer-to-Peer Networking platform, including:

• People Near Me and Application Invite: The ability to discover nearby people and send invitations to initiate multi-party activities.
• Serverless name resolution: The Peer Name Resolution Protocol (PNRP) enables secure advertisement of machine, user, or application resource names either on a local subnet or over the Internet.
• Multi-party messaging and data synchronization: The ability to create secure multi-party groups that share a replicated data store.

In addition, the feature uses Web Service Discovery, Windows Distributed File Replication Service (DFRS), and Windows Remote Desktop Protocol (RDP) to respectively support meeting session discovery, file exchange, and desktop/application streaming.

Top of page

Windows Meeting Space and IPv6

Windows Meeting Space uses Internet Protocol version 6 (IPv6). IPv6 was developed by the Internet Engineering Task Force (IETF) to serve the growing demands of today’s Internet. IPv6 is commonly associated with its large network address range, which was developed to support the exponential growth in the number of Internet-connected hosts and devices and prevent the threatened exhaustion of available IPv4 addresses. However, IPv6 provides several other features, including integrated support for IP security (IPsec) and simplified client address allocation.

By using IPv6, Windows Meeting Space gains several advantages:

• Ubiquitous addressing: IPv6 allows every Windows Meeting Space participant to have a unique global IP address. Though Windows Meeting Space is typically used on a single local area network (LAN), the feature supports meeting sessions that cross subnets or even span the Internet. By allowing each host to have a unique address, IPv6 ensures that all Windows Meeting Space users can ultimately connect to each other without conflict. In the IPv4 world, the lack of available addresses has prompted the use of network address translation (NAT) devices that assign private, or hidden, addresses to each host; unfortunately, these private IPv4 addresses are not globally unique or routable, so client hosts cannot communicate with each other easily.
• Improved connectivity: IPv6 facilitates improved end-to-end connectivity, enabling Windows Meeting Space sessions over the Internet. Microsoft Windows provides technologies such as Teredo and 6to4 that enable end-to-end IPv6 connectivity over the existing IPv4 Internet. Teredo allows IPv6-aware hosts to tunnel traffic to each other over the IPv4 Internet; Teredo is able to operate transparently through most existing NAT devices and home gateways. Teredo connectivity is transparent to IPv6 application developers, meaning that developers are freed from the worries of manual NAT traversal. On the other hand, IPv4 developers must often build and deploy custom NAT traversal techniques within their applications. The 6to4 protocol allows an Internet-connected host or router (such as a next-generation home gateway device) with a public IPv4 address to tunnel traffic over the IPv4 Internet. Again, the presence of 6to4 connectivity is transparent to application developers.
• Automatic address configuration: IPv6 enables Windows Meeting Space to deliver a fast and smooth ad-hoc networking experience. For each active network interface, clients automatically generate a unique link-local IPv6 address (suitable for communicating with other hosts on the subnet) without relying on the presence of a router or DHCP server to centrally assign addresses on that network. This address allocation scheme ensures that hosts can begin to communicate without any delay upon creating an ad-hoc wireless network or upon plugging into a network hub or switch. Although IPv4 supports ad-hoc networking, automatic network setup is traditionally slow.
• Native support for security (IPsec): IPv6 provides native support for IPsec, allowing Windows Meeting Space to operate efficiently over both insecure and secure IP networks. Increasing numbers of enterprises are deploying IPsec to enable Server and Domain Isolation.
• Compatibility with emerging government and national standards: Several government organizations, such as the United States Federal government, have mandated a transition to IPv6 for their internal systems; likewise, because of the short supply of IPv4 addresses, ISPs in various parts of the world—particularly Asia—are deploying native IPv6 support to their enterprises and consumers. By using IPv6, Windows Meeting Space can be deployed confidently with the knowledge that it will be compatible with these technology mandates.

Top of page

Barriers to IPv6 Deployment and Development?

IPv6 support is available on Windows XP Service Pack 1, Windows XP Service Pack 2, and Windows Server® 2003. IPv6 is enabled by default on Windows Vista and Windows Server “Longhorn” (now in beta testing)

Many developers fear relying on IPv6 because it is not widely deployed on today’s Internet. However, as demonstrated by Windows Meeting Space, IPv6 can be used readily by mainstream enterprise and consumer applications.

Over small LANs, IPv6 requires no special network support. Each host automatically selects a link-local IPv6 address, and IPv6 traffic travels freely within most LAN environments. Similarly, over the Internet, hosts also select Teredo IPv6 addresses to operate seamlessly across most consumer home networks and NATs.

Within the enterprise environment, cross-subnet operation requires network-level support for IPv6. Most enterprises are not yet ready to create native IPv6 networks, but various tunneling technologies are readily available to support IPv6 operation over existing IPv4 corporate networks. The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) enables IPv6-aware applications to co-exist with IPv4 applications and networks. To support ISATAP, many enterprises will not need to do anything special, because enterprise-grade routers support ISATAP. Many enterprises have rapidly enabled IPv6 connectivity by deploying an ISATAP router (supported by Windows Server 2003).

The potential code complexity and developer training were other important considerations in choosing to support IPv6 within the Windows Meeting Space feature. Fortunately, the transition from IPv4 to IPv6 (and indeed from IPv4 to dual IPv4/IPv6 support) proved to be quite straightforward from both perspectives. Support for IPv6 involves relatively minor changes to traditional Windows Sockets development—primarily requiring the use of version-agnostic data structures and explicit support for multiple active host IP addresses. In addition, Microsoft provides a handy Checkv4.exe tool to help catch programming errors that block IPv6 usage.

Top of page

Conclusion

Windows Meeting Space relies on IPv6 to provide ubiquitous addressing, improved Internet-wide connectivity, and rapid auto-configuration in ad-hoc network environments. Use of IPv6 ensures that the feature can easily take advantage of Quality of Service (QoS) in the future and IPSec within enterprises that mandate its use. Finally, IPv6 future-proofs the feature for deployment within evolving network environments world-wide.

Though many developers have feared relying on IPv6 because of its limited deployment, Windows Meeting Space demonstrates that IPv6-based applications can still operate in existing IPv4 environments by relying on a combination of transition technologies (Teredo, 6to4, and ISATAP) and automatic link-level operation. Most important, IPv6-based applications require no or minimal new network configuration.

As a leader in enabling broad deployment of IPv6, Microsoft is providing full IPv6 compatibility within Windows Vista. Features such as Windows Meeting Space further demonstrate the value and viability of IPv6 in today’s enterprise and Internet environments. Developers should work to make their applications IPv6 aware, joining Microsoft in laying the foundation for the future of networking.

Top of page

For More Information

• Windows Meeting Space
• Windows Peer-to-Peer Networking Platform
• IPv6
• Teredo
• ISATAP: A whitepaper, " Manageable Transition to IPv6 with ISATAP", provides useful information on using ISATAP to transition to an IPv6 network.
• IPSec
• Developing with IPv6

	Top of page