What does it mean to integrate wired and wireless LANs?
Now that 802.11n is fast and reliable enough to compete with 100 Mbps Ethernet, edge network access will transition from predominately wired to predominately wireless. Most offices still depend on wired Ethernet to enable edge network access by laptops, desktops and VoIP phones in private cubicles and offices, but Gartner expects 70% of all new enterprise LAN ports to be wireless by 2012. As this transition occurs, most business traffic will end up traversing both wired and wireless links, and business success will increasingly depend on Wi-Fi.
Gone are the days when Wi-Fi could be treated as a casual network add-on, used to deliver best-effort access to business email and the public Internet from communal areas like meeting rooms.
This means that network engineering, management, security, and planning tools/processes will need to become not just wireless-aware but wireless-savvy. For example, basic Wi-Fi tools that once simply reported errors and signal strength must be augmented. Ensuring availability in a network composed of both wired and wireless hops requires integrated service assurance systems that understand both wired and wireless technologies and are capable of automatically diagnosing and avoiding problems no matter where underlying failures occur. Without these integrated processes and tools, businesses will not be able to efficiently and effectively operate networks that make extensive use of both data link technologies.
802.11n: Ready for enterprise primetime
Network planners and administrators who have used 802.11a/g are all too familiar with legacy Wi-Fi pitfalls. Access points that maxed out at 54 Mbps, delivering half that throughput, had to be positioned to avoid co-channel interference. With only three non-overlapping channels in the crowded 2.4 GHz band, the number of users and devices that could be supported in any given location was limited. For users in motion, such as those using VoIP handsets or smartphones, dead spots broke connections and problem areas were hard to fill cost-effectively.
802.11n addresses all of these shortcomings, resulting in Wi-Fi products that are truly ready for primetime enterprise network deployment. First, 802.11n access points use multiple-input multiple-output (MIMO) antenna systems to carve more capacity out of each frequency. These antennas send data over multiple spatial streams to increase maximum data rates -- a 2x2 AP can reach 300 Mbps, while a 3x3 AP tops out at 450 Mbps. This additional capacity can be used to transfer data faster -- application throughputs in excess of 200 Mbps are now possible -- or capacity can be used to support user densities an order of magnitude greater than legacy APs.
In addition, instead of being limited to 2.4 GHz (like 802.11g) or 5 GHz (like 802.11a), 802.11n APs can operate in both bands -- often simultaneously. Avoiding co-channel interference becomes easier with more airspace available to everyone. 802.11n APs in the 5 GHz band may even find enough clean air to use channel bonding -- that is, double-wide 40 MHz channels to support demanding high-throughput applications like video streaming. Those applications can also benefit from 802.11n efficiency improvements, such as block acknowledgment, which reduce network overhead.
For many, the best news about 802.11n is not throughput or capacity but reliability. Specifically, 802.11n turns a destructive radio behavior -- multipath -- into an advantage. Multiple spatial streams can be used to send the same data redundantly to better overcome problems that plague a particular "path" through the air between transmitter and receiver. Using new techniques like transmit beamforming, 802.11n APs can automatically fine-tune how they interact with a given client based on recent history. As a result, 802.11n devices tend to maintain higher data rates over greater distances and experience fewer dead spots.
Primetime means demand for integrated wireless LAN
Today, hundreds of business-grade products (APs and clients) have passed 802.11n certification tests. Product features vary. For example, not all 802.11n APs support simultaneous dual-band operation or 3x3 MIMO, but all have demonstrated interoperability using core features that make them considerably more robust and mature than legacy Wi-Fi products.
As a result, businesses that have delayed wireless infrastructure investments, broader wireless rollouts, or mobilizing new business applications are likely to find that technology is no longer holding back these initiatives. In a May 2009 study conducted by Aberdeen Group, 52% of companies said they planned to improve their WLAN to deal with usage growth (including voice and video) that would otherwise degrade performance. Increasing staff productivity was cited as a top pressure by 37%, while 27% said their staff needed more flexible data access.
Companies that had already invested in 802.11n reported achieving all of these benefits. Even "average" companies reported 114% growth in WLAN traffic, a 60% increase in wireless coverage throughout their offices, and a 44% reduction in downtime. In another related Aberdeen survey of end users, perceived business benefits reaped from a more reliable, secure and higher-performance WLAN included not just better productivity and flexibility but increased customer satisfaction, accelerated decision making, and greater work-team collaboration.
In short, integrating contemporary, mature wireless technology into enterprise networks is clearly "a good thing." The real question then becomes how best to go about integrating wireless network devices, tools and processes to make the most of these new infrastructure investments. In our next tip, we will discuss how to prepare your wired network for wireless integration in order to avoid creating bottlenecks, degrading performance, frustrating users, or otherwise preventing wireless from achieving its intended benefits.
About the author:
Lisa A. Phifer is vice president of Core Competence Inc. She has been involved in the design, implementation and evaluation of data communications, internetworking, security and network management products for more than 20 years and has advised companies large and small regarding security needs, product assessment and the use of emerging technologies and best practices.
This was first published in December 2009