Does your Wave2 AP need NBase-T?

Cisco recently launched the 2800 and 3800 series 802.11ac wave-2 access points. The 3800 Datasheet quotes a theoretical maximum throughput of 5.2Gbps when operating in Dual 5GHz radio mode (2 x 2.6Gbps). If you ran two cables to your AP you could use the second ethernet port to create a 2 x 1Gbps LAG. However there is still some debate about whether 2Gbps of throughput is sufficient for a single-radio Wave2 AP.
Some companies may not be willing to invest the time and expense to swap out their copper for fiber or run yet more copper to their APs. The NBase-T standard 802.3bz provides an alternative approach, promising speeds of 2.5Gbps or 5Gbps over Cat5e cabling over 100 Meter runs.

Peter Jones from Cisco is the chair of the NBase-T alliance and presented to us in Tech field day on the new 802.3bz standard and the technology behind it. Cisco terminology for NBase-T-like functionality is ‘MultiGigabit Ethernet’. Currently the Cisco Catalyst 2k, 3K, and 4K switching line have specific models or line cards which support a number of combined UPoE/MultiGig ports. The reason for new hardware is that new digital signal processors (DSPs) are required to achieve the 2.5Gbps and 5Gbps rates.
This isn’t the first time Cisco have used a hardware solution to extract greater throughput from existing cabling plant. The standards-based LRM transceiver allows you to run 10Gbps over existing OM2 multimode fiber. The proprietary Cisco BiDi transceiver allows you to run 40Gbps of a standard duplex pair of OM3 or OM4 multimode fiber. In both of those solutions the transceiver got smarter – however with NBase-T we need new switches or line cards.

What’s the business case?

You can start small by adding a MultiGig 3850 model such as a WS-C3850-24XU to an existing 3850 stack or add a MultiGig line card to your 4500. However I recommend that you step back and look at the broader picture before you jump into this new technology.
Will your AP throughput require NBase-T? – If you choose a dual-radio Wave2 AP you double your demand, but do you need dual-radio AP? I’m not a wireless guy, but I suggest you perform due diligence to avoid overbuilding your infrastructure. In short, do a trial if you can and create a business case based on real-world expected throughput.
What is the pay-back period? – When will we see APs with 10G fiber connections? Will you get enough value from your Multigigabit switch ports and APs before fiber-terminated APs are launched. Talk to multiple vendors about their roadmaps.
Standards – The standard is close to ratification is not yet fully ratified. Cisco is shipping MuliGigabit support rather than NBase-T support. This may be a small risk, but it’s a risk you’ll need to quantify.
InterOperability – If you do commit to NBase-T, does your second choice AP vendor inter-work with your current switch?

Sherpa Summary

Cisco did a great job of presenting an integrated solution for Wave2 technology. I think NBase-T is really cool technology and I’ll wager that 802.3bz will eventually be widely deployed. But I recommend that you fully examine the requirements and constraints before jumping into any new technology.



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