1. Wake On LAN (WOL) benefits:
· Achieve a higher success rate for Configuration Manager Activities.
· Reduces the associated network traffic during business hours.
· Conserve power by not requiring computers to be left on outside business hours.
2. Wake On LAN can be used on the following scenarios:
· Software updates deployment with deadline:
Configuration manager 2007 Send a wake-up transmission prior to the configured deadline for a software update deployment
Wake-up packets are sent only to computers that require the software updates and have not already installed them.
· Mandatory advertisement for software distribution or task sequence:
Configuration manager 2007 Send a wake-up transmission prior to the configured schedule of a mandatory advertisement, which can be for software distribution or a task sequence.
3. Walk On LAN overview:
· Wake-up packet transmissions are sent only from primary site servers only.
· The default port used by Configuration Manager 2007 to send wake-up packets to target computers is UDP port 9 and can be changed form site settings
· Secondary site servers or other computers cannot be configured as proxies to send wake-up packets.
· Wake-up transmissions are not sent to clients when they are on the Internet. Wake On LAN transmissions are always sent at the scheduled time.
· Wake On LAN independently enabled or disabled for any site in the Configuration Manager 2007 hierarchy
· Due to advertisements and software update deployments are inherited to child sites, the site server in the child site is responsible for sending the wake-up transmissions to its assigned clients if the site is enabled for Wake On LAN.
· If Wake On LAN is disabled on a child site, child site will not send the wake-up transmissions to its assigned clients, and client computers in that site will not be sent wake-up packets.
· ConfigMgr 2007 Client registers the system as busy for the specific wake-up task it receives, this prevents the computer from going back into a sleep state based on its power management settings before the task can complete.
· Wake On LAN does not return computers to a sleep state and you need to configure power management schemes to shut down or hibernate after a period of inactivity.
· Computers are woken up before the scheduled activity by 3 minutes before the scheduled activity to ensure that they have completed startup, this setting can be configured with the transmission offset option in a Wake On LAN advanced setting.
· Mobile devices do not support Wake On LAN capability.
· Clients running Systems Management Server (SMS) 2003 do not support Wake On LAN.
· Wake On LAN in ConfigMgr 2007 supports waking up computers in sleep states S1 through S5
4. WOL transmission methods
· Unicast transmission
o Unicast transmission wake-up packet uses the IP address of the target computer from hardware inventory to route to the target computer's subnet, and it uses the Media Access Control (MAC) address of the target computer from hardware inventory to construct the wake-up packet. When the wake-up transmission reaches the target computer's subnet, the wake-up packet is sent directly to the target computer, and If the target computer has changed its IP address since it last sent its inventory information, the wake-up packet will reach the wrong computer but it will not wake it up because the MAC address in the wake-up packet transmission will not match.
o Switches must forward UDP packets
o Unicast transmission is secure solution than subnet-directed broadcasts because the packet is sent directly to a computer rather than to all computers on a subnet.
o Consumes less network bandwidth than subnet-directed broadcast transmissions.
o Unicast transmission is supported with IPv6.
· Subnet-directed broadcasts
o Subnet-directed broadcasts transmission wake-up packet uses the Media Access Control (MAC) address and IP subnet address of the target computer from hardware inventory, The wake-up transmission is sent to the computer's last known subnet, and it is then broadcast to all computers on that subnet, and the computer that has the MAC address specified in the wake-up transmission will respond.
o Routers must be configured to forward subnet-directed broadcasts.
o Subnet-directed broadcasts are not supported with IPv6
5. Wake On LAN Prerequisites
· Network cards must support the standard magic packet format.
· Computers must be configured for wake-up packets on the network card and in the computer BIOS.
· If subnet-directed broadcast configured, all routers between the site server and target computers must allow IP directed broadcasts, and support IPv4.
· Hardware inventory must be enabled, and completed an inventory schedule.
· Client computers must be running the Configuration Manager 2007 client.
6. Sleep States for Wake On LAN
· S0: The computer is on and fully functional.
· S1: The computer appears to be off with the CPU stopped. RAM is refreshed, and the computer is running in a low power mode.
· S2: The computer appears to be off with the CPU stopped. RAM is refreshed, and the computer is running in a lower power mode than S1.
· S3 (Standby): The computer appears to be off with no power to the CPU. RAM is in slow refresh.
· S4 (Hibernate): The computer appears to be off with no power to the hardware. System memory has been saved as a temporary file on the hard disk.
· S5 (Off): The computer is off with no power to the hardware, and the operating system has been shut down without saving system memory to disk.
Stephen Leacock - "I detest life-insurance agents: they always argue that I shall some day die, which is not so."