January 19, 2015

Spiceworks 802.11ac Tech-Talk Q&A

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802.11ac Gigabit Wi-Fi technology is delivering bigger and better Wi-Fi today. Not only are we seeing higher data rates and wider support in client devices, but also we are seeing a strong movement in WLAN design towards the 5Ghz band that’s helping to drive adoption.

As we have learned, 802.11ac is shipping in two waves. Wave1 is available now and is an evolutionary step above previous generations, while Wave2 is set to raise the bar offering revolutionary technology such as Multi-User MIMO (MU-MIMO).

Recently I had a great opportunity to present an 802.11ac tech-talk to the Spiceworks Community. The webcast was well attended by both “Spiceheads” and Extreme Networks followers. The discussion highlighted the elements you need to know about 802.11ac Wave1 and Wave2, and drove many great questions from the audience.

Having run out of time during the webcast, even after answering a ton of questions, I thought to respond to a few of the remaining questions within this blog.

If the following Q&A is of interest, I encourage you to watch the webcast replay.

Spiceworks 802.11ac Tech Talk – Q&A

1. What is the rule of thumb when planning for multi-generations of client devices (a/b/g/n/ac)?

A: Very simple – you must plan for the lowest common denominator. Always keep in mind that client device capability is what governs the “speed” of your network.  It is a balancing act, however, and you need to think about both today and tomorrow. Is you network likely to see a refresh of new devices this year? If so, plan accordingly. One hard rule, no question: Design and optimize for 5Ghz today!

2. Does 802.11ac differ from other 802.11 protocols with respect to security? 

A: 802.11 attacks are happening at the L1/L2 stack, specifically targeting potential vulnerabilities (such as weak encryption) or attempting to disrupt services (such as DoS attacks). As in the past, 802.11 attacks are not bound to the offered protocols – a/b/g/n/ac – on a given AP. That said if you are utilizing a WIPS solution it should include support/visibility across the servicing APs and client devices to decode the protocols that are in use.

* For more thoughts on utilizing WIPS, check out my blog for my list of deployment recommendations.

3. Does MU-MIMO groups require specific wired VLAN mappings at the AP?

A: As discussed, MU-MIMO will operate with groups of 2-4 client devices, chosen in real time, operating over the RF. Flexible WLAN solutions, like IdentiFi wireless will not force binding of grouped client devices to be on the same VLAN for traffic flowing from the wired network. It’s a great question to ask your current vendor as it shouldn’t be a limitation in anyone’s implementation.

* There are a number of unknown factors when it comes to MU-MIMO, today, check out my blog discussing some of the unknowns.

4. Can you explain the difference of 160Mhz vs. 80+80Mhz channels?

A: Simple answer is that 160Mhz will use 8 contiguous channels (i.e. 36,40,44, 48,52,56,60,64), while 80+80Mhz will use non-contiguous channels (i.e. 36,40,44,48 + 149,153,157,161) to build 8x 20Mhz channel widths.  In real world, even using DFS channels, utilizing 160Mhz or 80+80Mhz channels without overlap is unlikely without inducing interference.  Note that 80+80Mhz will be offered through beacons, and clients that can support it will have opportunity to use it. Keep in mind that Wi-Fi will be backwards compatibile for older clients that only support 20Mhz or 40Mhz channel widths.

5. Will 5Ghz become as saturated, and interference prone, as 2.4Ghz is today?

A: Anything is possible, but given the number of available channels on 5Ghz it is unlikely. A strong design recommendation is to utilize 20Mhz or 40Mhz channels deployed in smaller cells. Channel reuse remains as a major factor when trying to optimize overall network bandwidth/throughput. In the future we may see added channels to the 5Ghz spectrum through governing bodies like the FCC in the USA. At that point, we might be in a better position to utilize 80Mhz or even 160Mhz in the right enterprise deployments.

* Looking for more insight on Wi-Fi interference? Check out my blog discussing this topic.

Thanks for taking the time to join us on the Spiceworks 802.11ac tech-talk webcast, or watching the posted replay. I’m looking forward to future opportunity to chat with the Spicehead community again!

Please feel free to add your own questions to the comments section of this blog if they arise after listening to the recording.

About The Contributor:
Kate Gilbert

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