How does it work?

By using Wake on Demand (on your Mac) and Bonjour Sleep Proxy (provided by an AirPort device or Apple TV), you can save energy and reduce costs while still ensuring full access to all your shared services. You can also remotely access shared services across the Internet via Back to My Mac.

Wake on Demand works by partnering with a Bonjour Sleep Proxy running on your AirPort Base Station, Time Capsule or Apple TV (when no AirPort Base Station or Time Capsule is present on the network). Note: Apple TV will act as a Bonjour Sleep Proxy even if it is in sleep mode.

Any Mac on your network that has Wake on Demand enabled in Energy Saver preferences will automatically register itself and its shared services with a Bonjour Sleep Proxy. When the Mac is in sleep mode and a request is made to access a shared service on the Mac, a Bonjour Sleep Proxy asks that Mac to wake and handle the request. Once that request is complete, the Mac will again register with the Bonjour Sleep Proxy and go back to sleep at its defined sleep interval in the Energy Saver preferences. Note: For ideal performance, you should have twenty or less Macs using Wake on Demand per Bonjour Sleep Proxy on your network.

Notes

• With Wake on Demand enabled (see below) and your Mac in sleep mode, your Mac will occasionally wake for a brief time, without lighting the screen, in order to maintain active shared service registrations with the Bonjour Sleep Proxy. On some Macs, sounds from the optical drive, hard drive, or fans may be heard during these brief periods. Note: Removing a sleeping Mac from the network will automatically remove its registered shared services from the Bonjour Sleep Proxy.
• Bonjour Sleep Proxy runs on an AirPort Base Station, Time Capsule, or Apple TV (second generation or later)--when no AirPort base station or Time Capsule is present on the network--with the latest software updates installed.
• Portable Macs with Wake on Demand enabled will only perform Wake on Demand functions when they are connected to a power adaptor and either the built-in display is open or an external display is attached.

Examples of how Wake on Demand works

Key features

Automatic registration

With "Wake for Network access" or "Wake for Wi-Fi network access" or "Wake for Ethernet network access" enabled in the Energy Saver preferences, OS X will automatically detect the presence of a Bonjour Sleep Proxy service running on your AirPort Base Station, Time Capsule, or Apple TV and register its shared services with the Bonjour Sleep 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 shared services on your sleeping Macs. Any client that tries to connect to one of these shared services will cause the Mac to wake and provide the shared service to the client.

For example: On a home network with an AirPort Base Station, a Mac sharing an iTunes playlist goes to sleep. A Mac or PC user on the home network sees the iTunes playlist in its iTunes and clicks it. The Bonjour Sleep Proxy wakes the sleeping Mac and its iTunes playlist appears on the other Mac or PC ready to play shared media.
 

Setting up Bonjour Sleep Proxy and Wake on Demand

To properly configure your network and devices for Bonjour Sleep Proxy and Wake on Demand, follow the steps below:

Setting the Bonjour Sleep Proxy on your AirPort Base Station, Time Capsule or Apple TV

Install the latest software updates for AirPort Base Station with 802.11n, Time Capsule, or Apple TV (second generation or later) to enable it to act as the Bonjour Sleep Proxy. Once installed, your AirPort Base Station, Time Capsule or Apple TV (when no AirPort base station or Time Capsule is present on the network) will make itself available as a Bonjour Sleep Proxy to other devices on your network with no other configuration necessary. 

Setting up your Mac

Macs that ship with Mac OS X v10.6 or later have Wake on Demand enabled by default, but for some earlier Macs this option must be enabled using the steps below.

To enable Wake on Demand on a Mac follow these steps:

1. From the Apple menu, choose System Preferences.
2. From the View menu, choose Energy Saver.
3. 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 Wi-Fi network access - Your Mac supports Wake on Demand over AirPort only

Setting up clients

Any Bonjour client can interact with a Mac running Mac OS X v10.6 or later and cause it to Wake on Demand. For Microsoft Windows, you should install Bonjour for Windows.

Wireless Wake on Demand

You can verify that your Mac supports wireless Wake on Demand by following these steps:

1. Open System Information.
   • While holding down the option key, click the Apple menu and select System Information…
2. In the Network section, click Wi-Fi.

If you see "Wake On Wireless: Supported", your Mac supports Wake on Demand when connected to your wireless network and automatically registered with the Sleep Proxy Server. If you do not see "Wake On Wireless: Supported", your Mac can use Wake on Demand if it is connected to your network with an Ethernet cable.

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:

1. From the Apple menu, choose System Preferences…
2. From the View menu choose Network.
3. Select Wi-Fi from the list of network interfaces.
4. If the padlock icon in the lower left is locked, click it. When prompted enter an admin name and password to unlock.
5. Click the Advanced… button. 
6. In the Preferred Networks list under the Wi-Fi tab, click and drag the name of your network that uses Wake on Demand to the top of the list.
7. Click OK to save the settings.
8. Click Apply, then close System Preferences