802.11ac Wi-Fi takes the lead, but wired network has to play backup

As adoption of the new 802.11ac Wi-Fi standard picks up, wired networks must be ready to support faster speeds and greater capacities it brings.

Although he works at a state university, Derek Johnson isn't typically involved in college recruitment. As a network engineer, he deals with packets all the time -- just not the ones that deliver pamphlets about dormitory life.

But Johnson, the data communications coordinator at Fort Hays State University in Hays, Kan., discovered several years ago that those two paths would meet when the school invested in campus-wide Wi-Fi in a bid to attract more students. After maintaining several hundred legacy 802.11abg access points (APs) from Enterasys for years, Johnson recognized the network was due for an update. But halfway through a recent 802.11n rollout, it became apparent that the newest generation of wireless, 802.11ac, would better suit the students', faculty's and staff's need for faster Wi-Fi. The 200-acre campus is now blanketed entirely in 802.11ac APs from Aruba Networks.  

But such a dramatic overhaul cannot happen in a vacuum. To support the increased speed and capacity that 802.11ac offers, Johnson also upgraded his older 100 Mbps switches to support gigabit Ethernet. Since the 491 new 802.11ac APs have gone live, bandwidth consumption has increased by 30% in all parts of the network.

As more enterprises and other organizations start deploying the first wave of 802.11ac -- which boasts a maximum theoretical throughput of 1.3 Gbps -- networking professionals like Johnson are ensuring their wired networks are prepared to support the new wireless standard.

But with many enterprises already having deployed Gigabit Ethernet throughout their wired networks -- and with 10 Gigabit Ethernet gaining traction as prices come down -- networking pros anticipate 802.11ac will cause incremental adjustments rather than cataclysmic shifts over the next year or so.

With so few 802.11ac-capable laptops and mobile devices on the market, there is no wireless datapocalypse creating an urgent need to run 10 Gigabit out to the AP at this point. An increased reliance on wireless is, however, driving some network engineers to upgrade their core and edge networks to keep up with the ever-growing demand for faster speeds. For many early adopters, their 802.11ac deployments are just one, fortuitously timed piece of a broader network strategy.

The evolution of 802.11 standards


"If you're taking care of your network today and making systematic upgrades, you'll be fine," says Bradley Chambers, director of IT at Brainerd Baptist School in Chattanooga, Tenn., who is testing 802.11ac APs from Aerohive Networks. "I don't think you've got to rip and replace and put in $20,000 switches if today you're not [already] putting in that nice of a switch."

When Daniel Grim, chief technology officer at the University of Delaware, whose main campus is in Newark, Del., swapped out his traditional phone services for Voice over IP (VoIP) last year, he needed to upgrade his access-layer switches as well. He selected Juniper Networks' EX3300 series switches, which are Gigabit-capable and have 10 Gigabit uplinks. VoIP doesn't require that kind of bandwidth, but Grim needed the switches' Power over Ethernet capabilities. So when he and his networking team deployed 500 of Aruba's 802.11ac APs a few months later -- adding to his cache of 2,000 legacy 802.11n APs -- he was glad to have that switch capacity already in place. 

"In the end, we need it to support the wireless infrastructure," Grim says. "But I can honestly tell you we didn't talk about [needing] this for ac because ac is a recent development."

Will Wave 2 change everything?

Even in light of the recent ratification of Wave 2 of the 802.11ac standard -- the second and final phase of specifications, which promises maximum theoretical speeds of up to 6.7 Gbps -- few foresee an upcoming capacity crisis where the wired and wireless networks meet. Wave 2 also introduces a technology called multi-user MIMO that enables up to four users to transmit data simultaneously, which may require more attention to how that traffic is backhauled but not for some time. Only a few Wave 1-capable end-user devices are commercially available now, including Apple's latest version of the MacBook Air and Samsung's Galaxy S4 smartphone. It will be several more years before Wave 2-capable laptops, tablets and smartphones hit the market.

With the exception of those networks still harboring older 10/100 Mbps switches, it's unlikely that the access layer will need significant investment to support 802.11ac for most enterprises, according to Andre Kindness, a senior analyst at Cambridge, Mass.-based Forrester Research.  

"You hear in Wave 2 that the throughput is going up above a gig, so you're going to hear vendors out there saying, ‘You're going to need 10-gig connections to these APs,'" Kindness says. "But I struggle to [believe] that you're really going to get that much going through each AP that you're going to need more than a gig, at least not for a while. … People don't need to go out today and buy a gig or 10 gig to the desktop."

Johnson, of Fort Hays State University, is considering 10 Gigabit Ethernet for the future, but like Kindness, he isn't convinced that 802.11ac is creating an urgent need to adopt it now.

"I would say eventually we're going to get there, but to be honest, it's probably several years out just because to get the overall high throughput of 11ac, every device would have to support it at the highest level [of the standard]," Johnson says.

Chambers, of Brainerd Baptist School in Chattanooga, is also skeptical.

"There's a lot of talk about people's wired networks needing to be upgraded to 10 gig to take full advantage of 11ac. Those aren't bad ideas, but you've also got to look at your ROI for what you're doing," he says. "Do you need to spend 10 times the cost to get moderately better speed? In our situation, no."

With both waves of 802.11ac, however, there are some additional points to consider. Several new buildings at the University of Delaware were designed long before they were due to open last summer. Assuming that they would be deploying 802.11n APs, which only have one Gigabit uplink port, Grim and his networking team designed the buildings' networks to have only one Ethernet cable run out to each AP. But when the 802.11ac devices from Aruba arrived, they realized something was different about these APs, something that would affect how they designed networks in the future: The devices had two Gigabit Ethernet uplinks.

It was a surprise, but not a setback. A new dormitory set to open in the fall of 2015 will have two Ethernet cables pulled for each AP. If the team sees congestion in the buildings that have pulled just one cable, they will likely just add more APs to even out the load.

"I don't think that we're going to be expecting [that much traffic now], but we want to be prepared for it," says Mike Davis, the university's systems programmer, who oversees the network. "The dual Ethernet provides not only increased bandwidth, but it also in some ways provides redundancy, so that's been one of the driving forces for getting this done."

Upgrades likely in backbone

That's not to say next-generation wireless won't affect bandwidth needs on the wired network at all.

Early adoption of 802.11ac is moving faster than it did for 802.11n, according to Infonetics Research, which counted nearly 200,000 802.11ac APs shipped in the fourth quarter of 2013. Meanwhile, the number of users connecting to the corporate network via wireless LAN devices and campus switches is also slated to increase by more than 40% by 2018, reports the Dell'Oro Group, which chalks up the growth in large part to the fast adoption rate it expects for 802.11ac.

All the traffic that follows is likely to hit a chokepoint somewhere, and many networking pros expect that somewhere to be the backbone. The good news is that many IT departments have also recently upgraded their network backbones to meet the requirements of other projects besides wireless or as part of the regular refresh cycle.

Jacob Red, network administrator at the Senatobia Municipal School District in Senatobia, Miss., recently upgraded 55 of the radios in his legacy 802.11abg and 802.11n arrays from Xirrus to support 802.11ac in order to meet the requirements set by the Common Core State Standards Initiative, a set of nationwide educational standards that include bandwidth benchmarks. The current school year requires all parts of a network to support at least 100 Mbps per 1,000 students and staff -- translating into 250 Mbps for Senatobia. But that benchmark is expected to rise to 1 Gbps per 1,000 students and staff by 2018.

The move also drove him to upgrade his backbone switches from 1 Gbps to 10 Gbps, since he anticipates the network backbone will be the most taxed by the increasing traffic 802.11ac will likely bring.

"I can see the connection between our switches getting hit the hardest first," Red says. "As far as servers in-house that we host content on, those will eventually get hit, but we don't have a lot of stuff that gets a lot of bandwidth inside the data center. But I can see [that need emerging] in the next two to three years."

Chin Song, director of technology at the Milpitas Unified School District in Milpitas, Calif., which recently finished beta testing 802.11ac APs from Cisco Systems' Meraki unit, agrees that the new wireless standard is unlikely to be so "radically different" that it will require significant network upgrades outside the normal refresh cycle.

"When we upgraded [our APs to 802.11n], we put in CAT6a wiring for everything, so we have the ability to do a gig and even 10 gig through that copper," says Sean LaRussa, systems manager at the district, which serves 10,000 students across 13 schools. "With that forward-looking mentality Chin had, we didn't have to change anything [for 802.11ac]." 

At the University of Delaware, Grim had already upgraded his backbone to support 10 Gbps across most of the school before he deployed 802.11ac, and he already has his eye on moving to 40 or 100 Gbps in a few years. He also believes wireless will be driving much of the need for more capacity. But Grim acknowledges the timing of his move to 10 Gigabit was a fluke. Some much-needed grant money came through, and the price of long-range 10 Gigabit optics had fallen from $4,000 per port to $200 per port within a year. 

"I would like to hope the next time around, when we're talking about the next generation of Wi-Fi, we're thinking about this a little harder because Wi-Fi, in our experience, is really what's driving the demand for backbone bandwidth," Grim says. "It really would make sense for us to be designing around what the wired network requires, rather than just happening to put in enough capacity to handle it as a lucky break."

Larger pipes, faster WAN

Several networking professionals also say they expect the edge of the network -- points connecting to the Internet or a wide-area network (WAN) -- will also need larger pipes to handle increased wireless traffic if they want to take full advantage of 802.11ac.

"I think for most [people], their bottleneck is still their bandwidth coming into their building," says Brainerd Baptist's Chambers. "11ac is very fast, no doubt, but it ultimately depends on what your client is and what you're connecting to … so if you've got a 50-meg Internet pipe, and all you're doing is connecting to cloud services, 11ac isn't necessarily going to dramatically increase your speed."

Senatobia school district's Red has a Gigabit fiber WAN link and about two years left on the contract with his current service provider. He plans to request 10 Gbps the next time it goes out to bid, and he expects increased wireless traffic to need that bandwith the most.

"Once they have that gig connection, I can see how your bottleneck is going to be your Internet [pipe] because people are going to start wanting faster connections. It's just a matter of time," Red says.

Grim, who has three aggregated Gigabit links out to the Internet at the University of Delaware, says he's concerned not just about performance, but also about cost.

"I worry that as we get more capacity in the Wi-Fi network that people are going to start using services that aren't local here," he says. "A nightmare I have is that once we put all this traffic on the backbone, what's it going to cost to send it out to the Internet?"

This was last published in April 2014

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