Windows 8, 802.11w and Other Wi-Fi EnhancementsBy CWNP On 10/12/2012 - 21 Comments
Windows 8 introduces several very important enhancements to 802.11 networking either directly in the OS or through requirements in the Windows logo certification program. In this post, I will introduce you to these new wireless features.
Recently, Cisco published a blog about the bug in their software that prevented some Windows 8 wireless clients from connecting to their infrastructure solutions. This problem is related to 802.11w management frame protection (MFP). The problem is with Cisco software and not with Windows 8, but it is important to repair if you use Cisco Unified wireless in your environment. More on their bug-fix solution can be found here (https://ow.ly/eqrBR).
As one of the few vendors to mandate 802.11w support in native OS drivers, Windows 8 is leading the way here. However, it is important to be aware that older drivers (from Windows 7) are still supported on Windows 8 and when using those you do not get 802.11w support.
Microsoft has also enhanced the wireless support in Windows 8 in several other key areas. One key area is in power management. First, the power management is removed from the computer CPU and managed directly by the Wi-Fi device in most implementations. Power management is a standard part of 802.11. It allows the radio to be shut off, have frames buffered, and then wake to retrieve frames. The results of this change is extended power life due to the lessened use of the power consuming internal CPU of the computing device.
Additionally, with some Wi-Fi clients, Microsoft was able to reduce the interrupts (those actions requiring attention of the CPU managing the network in Windows 8 itself) by 80%. This reduction in interrupts equates to extended battery life as well.
The final power saving feature of Windows 8 native drivers is packet coalescing. Basically, broadcast frames (like beacons and other such frames) can be buffered at the device and then passed to the driver in groups of frames for processing rather than as individual frames.
Connected Standby is the term Microsoft is using to define their new power management support in Windows 8. The summary of all these features is that a PC can have the screen off and the system placed in a low idle state, but the network adapter can maintain a connection to the network. Your Windows 8 Metro style applications will continue to receive updates (think the weather apps on your tablets or phones) even while in Connected Standby.
Additionally, real-time communication programs will not fail. VoIP calls can come in while the computer is in the standby state. The result can be massive power savings for a company. Now, I know everyone likes to talk about “green,” but let’s talk about what really motivates companies to implement technologies like this - the “other” green! A company with thousands of computers acting as VoIP devices as well as computing devices could potentially save thousands every month using such features as Connected Standby.
Link Creation Speed
By link creation speed, I mean the time it takes to connect to the network and not the speed of the connection itself. Windows 8 can greatly reduce connection speeds when used with compatible hardware and Windows 8 native drivers. One method used is network list offloading. In this case, Windows 8 remembers your past networks and scans only for networks on those channels first. Assuming it finds a past network to which you have connected, this is likely the network to which you will want to connect again and it can provide those lists to you very quickly. Other networks will still be displayed, they will simply be added to the list a second or two later. In most cases, this provides the list of available networks faster (to the tune of 4-8 seconds, but we are very impatient about these things these days [smile]) and allows you to start the connection process earlier.
The primary area of link creation speed improvement is in the scanning. The new algorithms just mentioned can save as much as 8 seconds. The other most significant area is in the identification of the network. You know, that box that pops up and asks if this is a Home, Public or Work network? That processing has been reduced by between 3 and 4 seconds. The authentication and association process has not been enhance (same number of frames still required no matter what), but the IP address configuration has been enhanced slightly. In the end, link creation speed can be reduced by as much as 11 seconds. Going from nearly 12 seconds to as little as 1 second.
From the Microsoft perspective, Radio Management is not about the management of a specific radio, but the management of all radios. Windows 8 gives you a single place to go and manage, for example, your 802.11 radios or your 4G radios. Using this interface you can quickly turn on or off radios and airplane mode. In addition you providing you with the radio management interface, Windows 8 does automatic transition from one radio to another. For example, it will quickly move from 802.11 to mobile broadband or vice versa.
[caption id="" align="aligncenter" width="800"] The Windows 8 Metro Style Radio Management Interface[/caption]
The automatic transition from one network to another is the fastest I’ve seen by any OS vendor ever. When you, for example, come in range of an 802.11 network for which you have saved a connection profile, you will connect in less than one second. The good news is that your broadband connection is not dropped immediately. Microsoft chose to implement a graceful disconnect, which means that the existing connection is maintained for a period of time to allow applications to transfer over to the new network and, in almost every case, the new IP address.
Here is a great table providing a feature rundown provided at the Microsoft Build conference:
[caption id="" align="alignnone" width="800"] New 802.11 and Wi-Fi Enhancements in Windows 8[/caption]
The following table lists the requirements for WLAN devices desiring to have the Windows 8 logo (called Windows 8 native drivers in this post) compared with the Windows 7 logo certification:
[caption id="" align="alignnone" width="800"] Windows 8 Logo Requirements vs. Windows 7[/caption]
Frames Are Food,