Please note this maintenance will also impact Xbox 360 backward compatible titles on Xbox One.
All other Xbox One titles and services will not be affected. If you’re playing an Xbox 360 title during the maintenance, you may be disconnected from Xbox Live one or more times.
For the latest information during the maintenance, check the Xbox Live service status message at http://ift.tt/1sChgvC. For support help, be sure to hit up @XboxSupport on Twitter or make a “Support” post here on the forums.
Source: Xbox Live’s Major Nelson