WLAN Vendors: The NBASE-T Ball is in Your Court

I’m going to echo the position of Marcus BurtonLee Badman, and Andrew von Nagy. Despite the marketing push, there really is no need for > 1 Gbps link to a 802.11ac Wave 2 AP. Not at the access layer at least.

This Wi-Fi gauge goes up to 6.8 Gbps, so that means we need a 10 gig port for every AP, right?

Back to reality: 802.11ac Wave 2 is roughly 7 Gbps max with 8 spatial streams and 160 Mhz channel bandwidth, but most will use 4 spatial streams at max, cutting that in half. If you’re lucky you’ll will use 40 Mhz wide channels, cutting that four-fold. Then take off another 40% for layer 2 overhead and you get roughly 500 Mbps at half duplex on the wire. Maybe a gigabit with 80 Mhz channel width and absolutely ideal conditions that don’t exist outside of the lab.

Even if you have room for 160 Mhz wide channels, which might be possible if the FCC expands 5 Ghz unlicensed spectrum and then client adapters are updated to support those new channels, what is it that clients are using that calls > 1 Gbps of throughput? Remember that Wi-Fi is access layer technology. What applications are you supporting today or anytime in the foreseeable future that call for > 1 Gbps to a small group of clients?

Probably nothing coming over a WAN link. That leaves LAN applications. The list of potential applications provided by the NBASE-T Alliance doesn’t establish the need very well. Security cameras and signage systems?

It’s hard to think of many scenarios where it will be necessary to provide > 1 Gbps of throughput at the access layer. I can’t think of any of those that wouldn’t be better served by a wired solution.

Point to point Wi-Fi links in the distribution layer could benefit from NBASE-T, but how short must those links be to support 256 QAM, and is 8 spatial streams really possible outdoors with limited multipath? I don’t know the answers to those questions, but I don’t imagine that many locations exist that need > 1 Gbps of throughput that haven’t already provided that with fiber. We’re talking serious edge cases here, not typical enterprise Wi-Fi.

In any event, despite the hype, it will be a long time before the need for > 1 Gbps switchports extends outside of the network core and distribution layers.

WLAN vendors have an important decision to make here. Because 802.11ac appears to be the major justification for NBASE-T switches, I imagine they are under a lot of pressure right now. To get real interest in these new NBASE-T switches,  AP’s will have to be built with NBASE-T interfaces that use the faster speeds. I assume that those interfaces will be more expensive than standard gigabit interfaces. Given that NBASE-T supports 10 Gbps I bet they will be a whole lot more expensive than the gigabit interfaces used today. Just a guess though. Time will tell what this stuff really costs.

Will WLAN vendors become accessories to this marketing crime and include these potentially expensive interfaces in their Wave 2 AP’s? Aruba and Ruckus recently joined Cisco in the NBASE-T Alliance. We’ll have to wait and see their plans for the technology.

I hope that 802.11ac Wave 2 enterprise AP’s are still made with standard gigabit interfaces. Speciality AP’s like those used in point to point links could benefit from multigigabit interfaces, but the AP’s that are sold by the dozens for typical enterprise purposes do not. The added cost of an underutilized NBASE-T interface is not justified by real world needs.

Perhaps the usual product cycle will repeat itself. The first Wave 2 AP’s will have the highest end hardware and NBASE-T interfaces. Then the mid- and low-range AP’s that follow and actually get sold will have gigabit interfaces.

Whatever the case, it’s going to be interesting to see how the marketing hype about 802.11ac Wave 2 evolves as more people get clued in to its real world performance.

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