How does it work?
Wake on Demand works by partnering with a service running on your AirPort Base Station or Time Capsule called Bonjour Sleep Proxy. When Wake on Demand is enabled, any Mac on your network running Snow Leopard will automatically register itself and its shared items with the Bonjour Sleep Proxy. When a request is made to access a shared item on a Mac running Snow Leopard, the Bonjour Sleep Proxy asks that Mac to wake and handle the request. Once that request is complete, the Mac will go back to sleep at its regularly-scheduled interval as set in the Computer Sleep section of the Energy Saver preferences pane.
Below are some examples of how Wake on Demand works:
iTunes Sharing
Applications such as iTunes allow you to share your music and movies with friends and family on your local network. Wake on Demand allows for these machines to go to sleep, but wake up automatically to let family view your shared stuff.
Printer Sharing
In Mac OS X, you can connect a printer to a Mac and share it with other computers on the network. Wake on Demand allows for that Mac to go to sleep while idle, but wake up automatically when needed to handle a print job.
Back to My Mac
With Wake on Demand, you can access your Mac at home using Back to My Mac, even if your Mac is set to sleep.
Local File Sharing, Screen Sharing, other sharing services
As well as having your home Mac wake up automatically when you access it remotely using Back to My Mac, Wake on Demand also provides the same capability when you access your Mac locally from within your own home network, whether for File Sharing, Screen Sharing, remote login via SSH, or other sharing services.
Key features
Automatic registration
Every Snow Leopard-based Mac with "Wake for network access" enabled in the Energy Saver preferences will automatically detect the presence of a Bonjour Sleep Proxy service running on your AirPort Base Station or Time Capsule--and register its services with the proxy before going to sleep.
Works on any service
Because Wake on Demand uses Bonjour, it can handle any service that registers with Bonjour regardless of the underlying protocol.
Compatibility
Any Bonjour-enabled client (including both Mac and Windows) can discover Bonjour-registered services on your sleeping Snow Leopard-based Macs. Any client that connects to one of these services will cause the Snow Leopard Mac to wake.
Setting up Wake on Demand
To properly configure your network and devices for Wake on Demand, follow the steps below.
Setting up a Bonjour Sleep Proxy on your AirPort Base Station or Time Capsule
Install firmware 7.4.2 or later on your AirPort Base Station with 802.11n or Time Capsule to enable it to act as the Bonjour Sleep Proxy. Once installed, your AirPort Base Station or Time Capsule will make itself available as a Bonjour Sleep Proxy to other devices on your network with no other configuration necessary.
Setting up a Mac with Sharing enabled
Only a Mac running Mac OS X v10.6 can Wake on Demand. New Macs ship with Wake on Demand enabled by default, but for some earlier Macs this option must be enabled using the steps below. Macs that have Wake on Demand enabled will occasionally wake for a brief time, without lighting the screen, in order to maintain registrations with the Bonjour Sleep Proxy. On some Macs, sounds from the optical drive, hard drive, or fans may be heard during these brief maintenance wakes.
Additionally, portable Macs with Wake on Demand enabled will only wake on demand if they are plugged into power and either the built-in display is open or an external display is attached.
To enable Wake on Demand on a Mac running Snow Leopard:
- From the Apple menu, choose System Preferences.
- From the View menu choose Energy Saver.
- Select (check) "Wake for network access". Note: The "Wake for network access" option's text may differ depending on the capabilities of your Mac:
- Wake for network access - Your Mac supports Wake on Demand over both Ethernet and AirPort
- Wake for Ethernet network access - Your Mac supports Wake on Demand over Ethernet only
- Wake for AirPort network access - Your Mac supports Wake on Demand over AirPort only
The wireless network you use with Wake on Demand should be the first wireless network in your list of Preferred Networks. The wireless network priority can be set within the Network pane of System Preferences using the following steps:
- From the Apple menu, choose System Preferences.
- From the View menu choose Network.
- Select AirPort from the list of network interfaces.
- Click the Advanced button.
- In the Preferred Networks list, click and drag the name of your network that uses Wake on Demand to the top of this list.
- Click OK to save the settings.
Setting up clients
Any TCP/IP network client can interact with a Mac running Snow Leopard and cause it to Wake on Demand. For Microsoft Windows, Apple recommends installing Bonjour for Windows. Bonjour for Windows is included with iTunes and Safari for Windows.
Important note about wireless Wake on Demand
Some Macs do not support the ability to Wake on Demand when connected to a network wirelessly, and therefore must be directly connected to your AirPort Base Station or Time Capsule using an Ethernet cable. To verify that your Mac supports wireless wake for network access:
- Open System Profiler (located in /Applications/Utilities).
- In the Network section, select AirPort.
If you see "Wake On Wireless: Supported", your Mac supports Wake on Demand when connected to a wireless network and registered with the Sleep Proxy Server. If you do not see this entry, the Mac will only Wake on Demand when connected to your network with an Ethernet cable.