4G wireless WAN services with SLAs: Too good to be true?

Despite the hype, 4G is as much of a best-effort consumer service as 3G is for branches. But Sprint is trying to make 4G business-ready with its new wireless WAN services.

As branch offices multiply and enterprise bandwidth needs outgrow the capacity of T1 circuits, WAN managers are considering next-generation 4G technologies for some branches as a primary means of connectivity. But the problem remains that despite having much faster speeds, 4G is as much of a best-effort consumer service as 3G. Neither offers performance guarantees, and they often use consumer-grade hardware, such as USB modems and MiFi...

hotspots, to support businesses.

WiMAX operator Sprint Nextel Corp. is trying to change that perception with its new 4G wireless WAN service—dubbed 4G Enterprise WAN—which is backed by a 99.95% availability service-level agreement (SLA) and a pre-sales radio frequency (RF) assessment to ensure and optimize performance.

"This may be something that really fills a niche that'd evolved over the last 10 years," said Greg Wagnon, senior network engineer at Explorer Pipeline, a fuel pipeline operator beta testing the Sprint service. "If you've got a small branch office and you have difficulty running in a T1 or [the cost] may be prohibitive, and you're in a 4G area, this may be a product that fits you to a T."

With my 3G [access], you can call in a ticket to say, 'Hey, your tower's down,' but you're pretty much on your own. But with this ... they troubleshoot it like a regular T1 service.

Greg Wagnon
Senior Network Engineer, Explorer Pipeline

Verizon Wireless has not yet announced any comparable SLA-backed wireless WAN service for its 4G Long-Term Evolution (LTE) network, but it announced support for 4G WAN connectivity in Cisco Systems' Integrated Services Routers Generation 2 (ISR G2) branch routers earlier this year. AT&T has not yet launched its LTE network or publicized any potential WAN services around it.

For its part, Sprint also acknowledged that the 4G wireless WAN service won't fit all—if not most—branch deployments. For starters, wireless carriers have not agreed to any 4G domestic roaming agreements with each other, so the WAN service is only available within Sprint's 71-market WiMAX footprint.

Although Sprint quotes its average WiMAX speeds as being double or triple that of a 1.5 Mbps T1, the capacity is not dedicated to one business customer. Businesses would share last-mile access to the cell tower with Sprint's consumer customers. Additionally, signal strength will vary based on distance and line of sight to the cell tower. These factors make it difficult to define what size business or branch office is best suited for the service, according to Steve Coker, general manager of product marketing for business mobility solutions at Sprint.

"If all you're doing is basic transactional data services, you could support hundreds of people [at a single location] on this service. But if you're transferring a lot of big media files ... three to four people could use up the circuit," Coker said. "What we can say fairly confidently is there are lots of businesses out there—retail locations are a good example of this—that have existing needs supported by T1s and fractional T1s today. This can exceed their throughput needs [at a lower cost]."

Other carriers will likely offer similar 4G wireless WAN services for businesses, but it will likely be the small- to medium-sized businesses (SMBs) that adopt them first, if for no other reason than the 15-day installation time Sprint is promising, according to Kathryn Weldon, principal analyst at Current Analysis.

"There's probably a lot of built-up frustration in businesses around the long lead times [to install wired services]," Weldon said. "If I were an IT manager [at an SMB] and my location happened to coincide with where [Sprint's] 4G were available—and if I were sick of AT&T and Verizon and feeling locked in by them—then absolutely. Why not?"

 Enterprise wireless WAN service means 'they troubleshoot it like a regular T1'

Using cellular data networks for wireless WAN connectivity at a branch office has long been one of those do-at-your-own-risk decisions, which is why most WAN managers regard 3G as a backup to a wired connection or for remote locations where no other means of connectivity is affordable or available.

But the promise of 4G—coupled with Sprint's SLA and monitoring services—has persuaded Wagnon to beta test the 4G WAN service at one of his 70 locations: a new, small oil storage facility.

"With my 3G [access at other locations], you can call in a ticket to say, 'Hey, your tower's down,' but you're pretty much on your own," he said. "But with this, it's proactive monitoring. In other words, they say, 'Hey, we lost connection to your 4G modem. Can you verify power? Yeah, [you] have power. Uh oh, let's figure out what's going on,' and they troubleshoot it like a regular T1 service."

Getting a T1 circuit to the new site would have been too expensive and wouldn't meet Wagnon's bandwidth needs. Wagnon was unsure that 3G would adequately support the site. Although there would only be three users there full-time, he wanted to ensure he had a network connection with enough capacity and reliability to support Voice over IP (VoIP) over the WAN. Sprint's 4G wireless WAN service has lived up to his expectations.

"I've only got three people out there, and rarely are they all on the phone at the same time," Wagnon said. "Obviously, we would like to be blown away like, 'Oh my gosh! It exceeded my every expectation!' But no, this performed just like I wanted it to."

RF assessment, pro installation shape SLA for wireless WAN services

Sprint bases its performance guarantees in large part on its pre-sales site evaluation and professional installation services. Sales engineers conduct an RF assessment at the potential branch location—measuring signal strength in decibels and analyzing the potential impact of the terrain, weather and other factors, Coker said.

If those assessments are acceptable, Sprint engineers mount an outdoor modem and point it directly at the nearest 4G cell tower. This gives a business customer's traffic a leg up on indoor consumer-grade devices, Coker said.

The modem connects directly to the branch router through a Power over Ethernet (PoE) connection. It also has a 3G antenna pointed at the nearest 3G tower—which may be different from the nearest 4G tower—to act as a "hot standby" link if WiMAX goes down, Coker said. The 4G wireless WAN service has no data cap, and there is no charge for 3G if the 4G network goes down. The monthly fee also enables WAN managers to use 3G as an active link for load balancing purposes, but they will incur fees if monthly transfers exceed 5 GB. 

"Because it's a directional modem designed and built for outdoor use, it has a higher penetration level and very good access ... because it's pretty much going be a line of sight between the modem and the tower," Coker said. "And the likelihood of both the 4G and 3G network simultaneously going down is extremely low."

Wireless traffic is unloaded directly onto Sprint's MPLS backbone—never touching the Internet. However, there is no virtual private network (VPN) built into the wireless WAN service or additional layers of security beyond the standard, underlying encryption for cellular data traffic data, Coker said.

"It works like a VPN service, but it's not like traditional VPNs with IPsec tunnels," he said. "The overhead of doing that traffic encryption adds to the processing power and degrades the throughput capability."

Enterprises face another potential catch: Cellular data networks are incapable of supporting Class of Service (CoS) offerings commonly seen with wired WAN services. WAN managers can partially work around that by prioritizing traffic at the router so whatever leaves the branch first hits the cell tower first, Coker said.

"Neither 3G nor 4G networks implement Class of Service at the radio frequency layer, so it's one of the important caveats in understanding that when you select a service like 4G enterprise WAN, you don't get the same class of feature functionality of MPLS," he said. "You don't get guaranteed performance of your traffic over other cellular traffic."

Pricing for Sprint's 4G wireless WAN service may vary based upon the scope of the installation, but services with a two-year contract start at $249 per month, which covers the cost of equipment, installation and monthly service fees.

Let us know what you think about the story; email: Jessica Scarpati, News Writer.

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