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SDN architectures

SDN's Role in Carrier WiFi

Mobile carrier networks are reaching a tipping point. The emergence of the Internet of Things (IoT) means mobile networks will be handling an influx in big data, increased network traffic, and new types of connected devices, including smart cars, wearables and smart appliances.

These new connected "things" will share the same networks as PCs, tablets and smartphones, which are already bandwidth hoarders. Moreover, they are producers of traffic, not just consumers of it. With just smartphones and tablets to contend with today, carriers are already experiencing overloaded networks. And if the networks are not prepared, this flood of new connected devices could leave them paralyzed.

Whether it's through audio or video streaming (likely the largest source of new traffic), social networking, GPS navigation or shopping, mobile subscribers are increasingly gobbling up more and more mobile data at a rapid pace, reaching their monthly data limits faster each month. In order to provide value to subscribers, reduce customer churn and grow revenue streams, service providers will need to look at other ways to increase their bandwidth and reinforce their networks to help support the onslaught of connected devices. To address the needs of the networks and to remain competitive, carriers are turning to a familiar technology that could help offload some mobile data traffic from traditional networks -- WiFi.

While WiFi is nothing new to carriers, the way that technology is being used has shifted. One example of this is AT&T Inc. (NYSE: T). Of the major wireless carriers in the US, AT&T appears to be the only one to have cracked the code on offloading network traffic, mainly due to the more than 30,000 WiFi hotspots it has deployed. Once an AT&T subscriber comes into range of a hotspot, it immediately logs them on, and the subscriber is no longer consuming data via the carrier's cellular network. With these hotspots, AT&T has not only made data access cheaper for subscribers, but it has also made it more cost effective for itself. Hotspots are an efficient way to improve a wireless network by densely packing the cells that are sending and receiving data.

As a society, we've come to expect the same connectivity wirelessly that we get when hardwired to the Internet, though oddly the carriers have conditioned us to tolerating poor connectivity from our mobile phones. To achieve the full promise of mobility, wired and wireless LANs must be delivered faster and managed more easily. With the looming number of devices expected to connect to the Internet in the near future, what can networks do now to prepare for the data deluge?

Looking at how AT&T is leveraging WiFi for its subscribers, the underlying technology assisting in delivering unfettered service is… SDN. We've seen how SDN has transformed campus networks, data centers, and the cloud to date, so how can SDN help with WiFi? SDN-enabled WiFi is the best solution in delivering a consistent high performance connection to the growing number of connected devices. Already we are seeing this in the enterprise and on the campus.

Because of SDN's architecture, wireless networks can become more agile and can scale based on demand. There are four primary benefits to enhancing carrier network WiFi with SDN. First is the simplification of the networks. With SDN, the central control structure is consolidated, allowing for easier automation. Indeed, WiFi networks have long adopted this principle, though in proprietary ways. Having a single viewpoint allows for management of the wired and wireless LAN (as our members have demonstrated recently), simplifies network operations, and lowers costs. Administrators can view clients using a single tool, no matter which network they are on or are managing, while also gaining greater visibility into the unified network.


Want to know more about the emerging SDN market? Check out our dedicated SDN content channel here on Light Reading.


Policy control is another key benefit for SDN-enabled WiFi, as it allows for IT policies to be defined once and then enforced consistently across the wired and wireless LANs. This allows the network administrator to manage policy control across the entire unified network, ensuring users have a uniform experience, regardless of their access method, and network operators maintain consistent safeguards.

SDN can also be used to monitor network traffic flows -- specifically how the traffic should be routed -- and which application flows should have priority access. Now that SDN makes it easy to adjust priorities over WiFi networks, flow priority can be consistent across the integrated network. Ensuring the performance of critical business applications is a common IT objective. Take, for example, a typical IT scenario: A CEO is hosting a virtual meeting and it is essential that everyone can view the video. Before the meeting takes place, an SDN application can be programmed to automatically provision the network to allocate bandwidth and enforce a quality of service that ensures the broadcast of the video gets top priority on the network. To do this today without SDN would require a huge amount of manual configuration across both the wired and wireless networks. However, with SDN, provisioning is automated and easy.

Location services is another key benefit, especially since most users access the network wirelessly. SDN-enabled WiFi lets IT make dynamic decisions using the physical location of the user. This is particularly handy when dealing with locations that get inundated with multiple devices, such as conferences. This capability lets the network manager see what activity is taking place on the network by location and ensures that one location is not overloaded. In hospitality or entertainment settings, premium services to top-tier customers can generate additional revenue for site operators.

The promise of open SDN is that networks are no longer locked, proprietary, and difficult to program. But the extent of that openness and flexibility ultimately depends on each vendor's implementation and adherence to the standards. Limited implementations or proprietary twists will only serve to restrict the progress of SDN with customers.

It's an exciting -- and challenging -- time for carriers, as we start to see more connected devices join their networks. The coming of the age of IoT means that SDN will need to be implemented for subscriber retention, optimized QoE, network robustness and revenue growth.

— Dan Pitt, Executive Director, Open Networking Foundation

rangzhi 12/7/2014 | 4:51:23 AM
if you have a hammer everything looks like a nail SDN can defintely solve a lot of existing issues in Carrier WiFi, qos, roaming, so on and so forth. But I do not think this is the only direction we need to move forward. 

SDN is much more valuable that solving existing issues. It is actually better at creating new business models and operating models. By opening the control of the WiFi infrastructure, SMB and Mobile application vendors can do a much better job. 
danielcawrey 12/4/2014 | 1:23:52 PM
Re: WiFi roaming AT&T's leverage of wifi is smart, and this is what all carriers are going to need to do. 

What I am wonderin gis when we'll just have ubiquitous wifi, since right now penetraion for data is still not as good as I woud like. I still experience times when I cannot get data connected while tethered to my cell phone, even in some metro areas. 
VictorRBlake 12/4/2014 | 12:42:25 PM
WiFi roaming While it is true that SDN (which started with WiFi AP's actually) can help with the variety of possible different flow models required for WiFi, today the model has no mechanisms for inter-operator signaling and it doesn't look to be the focus any time soon. This means that SDN is a technology operating within a single provider's network. For a single provider, yes -- it could (potentially) make for faster switching of flows between AP's or from AP's to other (MIP/PMIP) gateways in the cellular network. But that only works when all of the devices are SDN managed by a single operator. When talk about roaming between operators, I don't see anything in SDN today that can help (directly). There is no signaling protocol for "moving flows." Yes, someone could build a SDN platform do do mobility in the cloud (aka cloud RAN), but that has nothing to do with WiFi AP's sitting in another providers network for which they may run a different LMP (local mobility protocol).
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