Usage of Teredo and IPv6 for P2P on Windows 10 and Xbox One

[Darrin Veit <dveit () microsoft com>]

Hi Everyone -

We've had very fruitful discussions with members of this community on Xbox One networking behavior, in particular 
concerning P2P multiplayer gaming activity. In an effort to continue that useful dialogue, we wanted to provide an 
informational update for Xbox One, but also share relevant details on upcoming Windows functionality in terms of Teredo 
and IPv6 usage. We also include some observations about IPv4 and IPv6 health that may be broadly interesting, 
especially as it pertains to network readiness for Xbox multiplayer via IPv6.


New Xbox experiences launching on Windows 10 will use Teredo for P2P communications
--------------------
Earlier this year we announced some Xbox functionality coming to Windows 10. One key feature of Windows 10 is enabling 
multiplayer gaming and chat functionality between Xbox One consoles and Windows 10 devices. This functionality on 
Windows 10 will behave similarly to how multiplayer works today on Xbox One, using Teredo for NAT traversal and IPsec 
for security. When used for Xbox Live enabled experiences, the Windows 10 Teredo client will prefer originating traffic 
from the IANA-registered port, 3074, when available. More detailed guidance on Xbox One behavior is linked at the 
bottom of this email.

It also should be noted that Windows supports a broad range of applications and a huge portfolio of great games outside 
of the Xbox Live ecosystem. In general, Microsoft encourages broad adoption of the recommendations in RFC 4787, RFC 
6092, and RFC 6888 to maximize the viability of P2P technologies for all.


IPv4's P2P health is degrading
--------------------
Qualitative and quantitative evidence available to us indicates that overall availability of functioning P2P 
connectivity on the IPv4 Internet is decreasing over time. In particular we are concerned that IPv4 address scarcity is 
forcing many small and medium market network operators to deploy carrier-grade NAT functionality. 

This often results in end-users being intractably stuck behind "strict" networks with degraded multiplayer experiences 
as a result. Healthy, standards-compliant IPv6 access is broadly needed, sooner rather than later. However, we have 
identified a few areas of concern in regard to IPv6 support that will hinder the efficacy of enabling multiplayer on 
IPv6.


IPv6 is being deployed, but not perfectly, jeopardizing IPv6 P2P 
---------------------
Across the Xbox One customer base, in particular for customers who play multiplayer games, we observe that a 
substantial minority (around 20%) of devices have native IPv6 configured. This represents a much higher IPv6 
penetration rate than Microsoft's other products and services report, as well as public data from other sources. 

However we have numerous concerns about IPv6's growth. We are often finding that retail customer premise equipment is 
configured with IPv6 disabled by default, requiring user action to enable. 

We've also encountered a very small set of reports where IPv6 latency and bandwidth performance are suboptimal compared 
to IPv4. Reports of this nature have usually focused on streaming media experiences and user concern that IPv6 is 
slower than IPv4 (i.e. "I get 1080P resolution with IPv4, and 720P with IPv6"). In the rare cases where these reports 
have been substantiated, the primary culprit has been differences in deployed CDN support. 

Also, some networking hardware and operators apply firewall policy to the IPv6 path contrary to RFC 6092 
recommendations. Of particular concern are configurations where unsolicited inbound IKE/IPsec traffic is not permitted 
in the default operating mode. Growth of these non-conformant configurations puts the P2P benefit of the next 
generation Internet in jeopardy. It would be incredibly regrettable if IPv6 necessitated the high level of 
configuration and inefficiency currently required for IPv4.


Deprecating public Teredo servers for Windows Vista and Windows 7
--------------------
On May 4th, 2015, we began deactivating Microsoft's publicly available Teredo servers currently configured as the 
default servers for Windows Vista and Windows 7 clients. This is a result of limited usage on those platforms and our 
desire to focus our operations on Xbox One and Windows 10.


If you read this far, you are awesome.

We will likely request a NANOG presentation slot later in the year to discuss these points, but we want to make sure we 
have sufficiently interesting and new things to discuss before swallowing up people's time.

Network operators and CPE manufactures are encouraged to reach out to our team at xboxteredo () microsoft com with 
operational questions. Please note that our most common reply will be "better documentation is coming later in the 
year," but we will try our best to respond to questions quickly.

Thanks for your time,

Darrin Veit & Christopher Palmer
Xbox Platform Networking 
Operating System Group

Current Xbox One Multiplayer Networking Guidance
-------------------------
http://download.microsoft.com/download/A/C/4/AC4484B8-AA16-446F-86F8-BDFC498F8732/Xbox%20One%20Technical%20Details.docx