wake on lan por usb wifi

http://www.intel.com/network/connectivity/resources/doc_library/tech_brief/wowlan_tech_brief.pdf



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Intel® Centrino® Mobile Technology Wake on Wireless LAN Feature Technical Brief 3
Contents
1 Overview ..................................................................................................................................3
2 Wake on Wireless LAN Summary.............................................................................................3
3 How WoWLAN Works...............................................................................................................4
4 Configuring WoWLAN on a Intel® Centrino® Mobile Technology Notebook Computer...........5
5 Secure Wireless Client Management........................................................................................5
6 Using WoWLAN in Enterprise Environments............................................................................6
6.1 Using WoWLAN in a Hospital Environment.......................................................................6
6.2 Managing Distributed Clients in a Warehouse Environment..............................................6
6.3 Updating Clients in an Office Environment ........................................................................6
7 Summary..................................................................................................................................6
1 Overview
The Intel® PROSet/Wireless Software v10.1 is the connection manager software that works in conjunction
with Intel® PRO/Wireless 3945ABG Network Connection hardware to connect your notebook computer to a
wireless LAN. Together they deliver next-generation Intel® Centrino® mobile technology to enable seamless
wireless connectivity to wireless LAN networks in your home, at the office, or on the road at hotspots in
airports, hotels and coffee shops.
The latest Intel® PROSet/Wireless Software release, v10.1 in conjunction with the Intel® PRO/Wireless
3945ABG wireless network adapter now support Wake on Wireless Local Area Network (WoWLAN) capability
to deliver the same level of manageability and security as the Wake on LAN (WoLAN) standard for wired
networks.
Note: The WoWLAN feature is not supported on Intel® PRO/Wireless 2200BG Network Connection and
Intel® PRO/Wireless 2915ABG Network Connection adapters.
2 Wake on Wireless LAN Summary
WoWLAN is based on the well-established WoLAN standard used in wired network environments to remotely
wake up computers using wakeup packets. WoWLAN enables on demand waking up of sleeping systems
remotely through a wireless association. It works with the same network management application that sends
the magic packet for WoLAN and does not require any changes to local operating system software used for
WoLAN.
The key benefit of WoWLAN for the enterprise is wireless clients can now be managed in the same way as
wired network assets. Corporate IT departments can use WoWLAN to persistently maintain connectivity to
automate software upgrades, deliver messages, manage corporate assets, and track the location of a
computer.
Intel® Centrino® Mobile Technology Wake on Wireless LAN Feature Technical Brief 4
Persistent connectivity is accomplished by using a management console sending IP packets to a wireless
adapter; then the adapter wakes the client from the S3 Standby/S4 Hibernate state to be managed by the
management console.
3 How WoWLAN Works
WoWLAN allows a network professional to remotely power on a notebook or wake it up from sleep mode
(S3 Standby/S4 Hibernate). By remotely triggering the notebook to wake up, the technician no longer needs to
physically visit each computer on the network to perform scheduled maintenance tasks.
WoWLAN works by sending a wake-up packet to a client notebook from a server machine that has remote
network management software installed. The Intel® Centrino® network adapter on the wireless client receives
the wake-up frame and powers on. Scheduled tasks can then begin.
For WoWLAN to function, the notebook computer must be associated with an Access Point (AP) prior to
moving into sleep state (S3/S4). The S3 power state, also known as Standby, is the first level of power-saving
mode. The S4 state, also known as Hibernate, provides additional power savings. A very low-voltage
connection to the Intel® PRO/Wireless Network Connection hardware allows the wireless adapter to continue
to examine signals from the associated Access Point (AP). The adapter periodically scans for the presence of
wake-up packet.
The persistent connection feature allows a wireless LAN connection to remain after the user logs off. This
allows system maintenance of the machine by network administrators in a similar manner as over a wired LAN
connection.
The Intel® PRO/Wireless 3945ABG Network Connection client wakes up on reception of a wake-up packet (e.g.,
from a management console). There are two types of management wake-up packets:
• Magic Packet* This wake-up packet wakes only a system targeted for start-up. It contains 16
contiguous copies of the receiving wireless network adapter’s MAC address. The MAC address is
unique to the network adapter in the system.
• Pattern Byte Matching (PBM): This wake-up packet enables the wake up a group of PCs with one
single packet. This is achieved by pattern byte matching or packet filtering. The system downloads a
series of patterns, configured by the administrator, to the wireless adapter, which in turn monitors
for the arrival of these patterns in a packet. If it finds these patterns, the wireless adapter generates
a wake signal to the system.
WoWLAN follows the similar steps of WoLAN. These steps are:
1. The operating system or network management application sets wake patterns in a wireless adapter
through standard Microsoft Object IDs.
2. While the system is in sleep state (system in S3/S4, adapter in D3), the adapter receives data packets,
attempts to match the pattern stored in the NIC to sequential bytes within the received packet.
3. The adapter on a sleeping system with WoWLAN capability wakes the system if a pattern match is
found and then responds to directed wireless traffic. For example, initiating a VoIP call.
Intel® Centrino® Mobile Technology Wake on Wireless LAN Feature Technical Brief 5
4 Configuring WoWLAN on a Intel® Centrino® Mobile Technology
Notebook Computer
If WoWLAN capability is enabled on a notebook computer, there is a Power Management tab on the wireless
adapter properties page. WoWLAN availability depends on whether the notebook computer manufacturer has
enabled WoWLAN in the circuitry of your computer.
The adapter properties page is accessible through the Network Connections window (Microsoft Windows XP).
The Power Management tab contains a checkbox Allow this device to bring the computer out of standby.
WoWLAN is enabled by checking this box. After checking the box, the Only allow management stations to
bring the computer out of standby box becomes active. Leaving this box unchecked configures the system to
wake on both Magic Packets and operating system defined programmable patterns. Checking this box
configures the system to wake only on Magic Packets. Operating system patterns are not set.
5 Secure Wireless Client Management
The WoWLAN protocol does not compromise the security of the wireless network. All wireless
communications conform to the security settings of the network. The same level of encryption and
authentication occurs between the wireless Access Point (AP) and the client PC during the wake-up process as
during normal network operations. For example, a WLAN using WPA2-Enterprise with AES protects WoWLAN
operations with the latest robust security. Once awake, the normal security software on the PC is fully
operational.
Intel® Centrino® Mobile Technology Wake on Wireless LAN Feature Technical Brief 6
6 Using WoWLAN in Enterprise Environments
Notebook computers are mobile assets. These highly mobile assets are best updated by management
solutions that are automatically triggered upon sign-on to the enterprise network. WoWLAN features are
designed for shared mobile resources within the business campus. The location of these mobile assets and
their connectivity status are challenges facing the IT professional trying to manage and update their software
configurations.
6.1 Using WoWLAN in a Hospital Environment
A hospital represents a large, complex technology infrastructure. Today’s hospital incorporates mobile
technology to allow the care staff freedom of movement and convenient access to patient care data. Located
throughout the hospitals are notebook computers and PDAs connected to wireless networks. Many of these
devices may be fastened to carts that are wheeled between rooms as needed. When the IT administrator
attempts to initiate software patches or updates or commence critical data backup, there is no assurance that
these devices are in active (S0) state. Hospitals can utilize the WoWLAN feature of Intel® Centrino® technology
notebooks to transmit wake packets to enable critical remote updates or broadcast critical messages to alert
staff of emergency conditions.
6.2 Managing Distributed Clients in a Warehouse Environment
In warehouse environments, mobile notebooks are commonly used to display pick orders or track inventory
location. The sleep states of these assets can be unpredictable. Using WoWLAN enables IT administrators to
deliver timely updates or backups of critical data remotely.
6.3 Updating Clients in an Office Environment
When there are shared notebooks in an office environment, the task of updating these assets is
complicated by the mobility of the computers and the multi-user logins. To manage these assets, the
IT administrator can use WoWLAN regardless of the notebook’s location and update the user
environments for all the login names.
7 Summary
The WoWLAN feature of Intel® Centrino® technology equipped notebooks allows IT administrators to provide
the same high level of remote management capabilities for wireless clients as they do for wired clients. With
WoWLAN, administrators can maintain powerful remote management capabilities by providing maximum
access to wireless notebook computers.