802.11 Fast secure roaming
Last Post: October 15, 2010:
Below mentioned Questions are from Sybex CWSP book & looking for explaination on each correct options. could you please suggest/guide
Q. Which of these methods allows an auth. & supplicant to skip an entire 802.1X/EAP auth. & proceed with 4 way handshake?
1. PMK Caching
4. Fast BSS transition
Q. what are some variables that an 802.11k 2008 compliant STA can use to initiate reassociation?
2. Channel Load Report
3. Opportunistic PMK caching
4. Neighbor reports
5. Authentication reports
There is a good explaination for your first question in http://www.cwnp.com/pdf/802.11_RSN_FT.pdf
All of four solutions belong to fast secure roaming (FSR) solutions. Just remember the following:
? 802.11-2007 defines one non-FSR solution of 802.1X/EAP authentication and two FSR solutions of pre-authentication and PMK caching.
Pre-authentication and PMK caching will skip the 802.1X/EAP process and proceed to the [b]traditional[/b] 4-Way Handshake.
? 802.11r-2008 defines a standardized FSR solution called FT.
FT will skip the 802.1X/EAP process as well, but proceed to the [b]fast[/b] 4-Way Handshake.
? Lots of vendors currently support a controller-based FSR solution called OKC. Consider OKC as a preview of 802.11r (FT).
Thanks for reply & nice explaination.
For Q1. book say only OKC & PMK Caching (pre-authentication option I added)
Could you please share your view about Q2?
Regarding Q2, I think the real answer is that there aren't really 802.11k-compliant STAs yet. Client adoption of this standard is delayed as vendors await (and dont' seem to care much about) Voice Enterprise from the Wi-Fi Alliance. Voice Enterprise will set the tone for the real-world implementations of 802.11k-based features. Until then, reassociation behavior is vendor proprietary. Even after then, 802.11k doesn't exactly dictate how a client's roaming algorithm should work. It is more about creating standardized processes that facilitate the collection of information that is relevant for roaming. The roaming algorithm will remain vendor proprietary, but the facilitation of information collection will be massively helpful.
As quick points to your question, RSSI will continue to be used as it is today. Two other similar measurements (RCPI--received channel power indicator--and RSNI--received signal-to-noise indicator) were added with 802.11k as well. 802.11k adds channel load reports and neighbor reports, which will be important for roaming decisions. Opportunistic PMK Caching is not defined by IEEE and is not a part of 802.11k. 802.11k doesn't specify an "authentication report."
If you don't already have a copy, you can snag the actual standard from here:
Wi-Fi Alliance plans to introduce the Voice-Enterprise program this year, but no official announcement is made so far. Without the Voice-Enterprise program, will 802.11r standard be widely accepted?
Voice Enterprise won't be released until at least Spring 2011. The Wi-Fi Alliance has plugfests (organized tests with participating products) planned into the late months this year, which means we've still got some waiting to do. Vendors (infrastructure and client) know that Voice Enterprise is in development and if they are interested, they will participate in the Wi-Fi Alliance's tests. The Wi-Fi Alliance has had a hard time getting the required number of vendors to participate thus far, which seems to be evidence that the vendors are the ones holding things up, not the Wi-Fi Alliance. So, if Voice Enterprise didn't come to market for some reason or another, 802.11r would not see the light of day. At least, not for several more years.
Good point, Marcus. Voice-Enterprise program (as well as vendors) is the main driving force behind 802.11r.
If 802.11r would not get widely accepted than expected, the weight of 802.11r in the CWSP exam might be adjusted, I'm afraid?
Yeah, that's right. We would be sure to remove 802.11r from the exam if it never made it to the real-world. I think it will come around, but it'll be slow.
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