It’s been a while now since we have been hearing a lot of buzz around software defined networking (SDN). SDN is a new approach to networking in which network control is decoupled from the data forwarding function and is directly programmable. The result is an extremely dynamic, manageable, cost-effective, and adaptable architecture that gives administrators unprecedented programmability, automation, and control, through abstraction of the underlying infrastructure. Implementing SDN via an open standard enables extraordinary agility while reducing service deployment and operational costs. Decoupled control and data planes help us build a centralized control plane that manages large number of data plane equipment, which is spread across network.
However, to date, all of these great benefits that SDN provides have been mainly focused on wired infrastructure. Why can’t we leverage SDN to simplify WiFi networks? After all, WiFi is fast becoming the preferred access technology for Internet/data connectivity. Mobile operators, multi-system operators (MSOs), enterprises, and government organizations are aggressively deploying Wi-Fi hotspots, to provide Internet connectivity. However, deploying thousands of WiFi access points (hotspots) and maintaining them across a city brings in lot of complexity is an expensive affair. The cost of access points itself is a big investment if we look at the number of access points an operator needs to deploy across a large city. Furthermore, maintaining the mesh of access points is a very complex and expensive proposition, given the high cost of truck rolls and maintenance staff. Here is where SDN can help reduce the cost of access points (CAPEX) and the operation and maintenance (OPEX) of thousands of connected access points.
To understand how SDN can help optimizing WiFi network deployment, let’s look at a typical hotspots deployment. Hotspots deployment need a centralized controller for WLAN functions such as RF management, authentication, roaming, billing, load balancing, and firmware upgrade. The access points (AP) for hotspots typically need to bridge internet traffic directly to the Internet Service Provider’s (ISP) network.The management of access points via controller in the cloud is also typically done by the ISP. However, this does not leverage the full potential of SDN for WiFi deployment. Besides the typical control functions that already sit on the cloud, we propose to move many complex FAT access points (AP) functions to the cloud while keeping physical APs to continue to do the data plane and FIT AP functions. If we move the software complexity to the cloud we can keep the access point hardware to a bare minimum while still providing richer functionality. The idea is to shift rich functions such as RIP, OSPF, NAT-Control, Firewall, IKE, DHCP, IGMP, PPPoE, ALGs-Control to the cloud. By adding an OpenFlow client to FIT APs, we can move all FAT functions to the cloud. Thus, moving complex features, which require high processing power, to cloud, significantly reduces the bill of material cost (BOM) of a WiFi access point, making it an inexpensive commodity. The significant cost reduction comes from the CPU, Memory and Clock that is used on these types of APs.
On the other hand, moving FAT AP functions to the cloud limits ‘truck rolls’ only to hardware installation and replacement. For maintaining the hotspots you just need to send your maintenance resource to the datacenter. It drastically minimizes the number of skilled resource required to maintain/reconfigure faulty access points, significantly reducing the operational expenses needed to maintain a large WiFi network with thousands of access points spread across a city.
Also, it helps operator to reserve highly skilled staff exclusively to non-routine task such as planning, re-planning, and enhancement of end user experience. This brings down overall deployment and maintenance cost, which can further accelerate the WiFi service deployment. However, in order to realize full potential of SDN in WiFi network, equipment vendors and service providers need solution that can be easily virtualized and an OpenFlow client that can be easily ported to any hardware platform.
We have been working on Wi-Fi /WLAN software solutions for many years, evolving our solutions as the technology and standards progressed. We have a complete WLAN software solution that implements CAPWAP – a client for WLAN access points and a controller for WLAN control switches or servers. Besides this, we have developed OpenFlow client (OFC) which is a portable implementation of the OpenFlow client functionality and is compliant with OpenFlow switch specification. Today, our OpenFlow client works on top of Linux or any other operating system, but in the future we might port it to specific OpenFlow switches.