The hub-and-spoke innovation was in routing traffic through, and enforcing security at, the wireless controller. However, the controller is now becoming the bottleneck for throughput and security enforcement as throughput needs rise. Trying to address this bottleneck using traditional WLAN solutions ultimately means an "either-or" trade-off: either a significant new investment in additional wireless controllers and wired switches or a greatly reduced QoS and user experience.
To take a step forward, what's needed is a "both-and" solution without compromise, one that helps you unleash the full advantages of your existing investment. Such architecture could maximize network performance and traffic without compromising QoS for video and voice features, security, mobility or survivability, while at the same time minimizing both capital and operational expenditures for a lower total cost of ownership (TCO).
This requires a fundamentally different model: an architecture that provides more intelligent routing at the perimeter of the network than the centralized hub-and-spoke model. This can be achieved with a more intelligent perimeter, using smart, adaptive wireless access points to offload some of the higher order intelligence and functionality of the controller itself.
Distributed intelligence allows more of the on-site data flow to be routed internally on the edge of the network using the 11n access points, rather than sending that data to the wireless controller and back. It maintains the strength of the entire WLAN infrastructure, while increasing the ability of the "spokes" to communicate directly with one another along an optimal path, even prioritizing more critical data (such as ) while providing full security and mobility services.
Not all 802.11n solutions are created equal, however. They can vary greatly in their range of capabilities. How well do access points interact with controllers, for instance? How many controllers are needed? What are the power requirements? How does the survivability of the system compare?
A more adaptive, reliable and intelligent architecture takes factors like these into consideration. It leverages the network's distributed intelligence to help unlock the full value of 802.11n solutions so they can both deliver a better quality of experience and make IT budgets go further.
By having more intelligence in the access points, during outages these access points can also serve a bridging function to reduce latencies. Since security is as important to the organization as solid network coverage and availability, it is important to make sure that any distributed architecture has enough application awareness to be self-healing without dropping VoIP calls and that it is able to deliver the same firewall capabilities as hub-and-spoke to avoid compromising QoS. This helps maintain network services throughout outages, ensuring the organization and its assets continue to benefit from continued local QoS prioritization, authentication, security policies and direct routing as well as backhaul failover to 3G.
Greater intelligence at the edge of the network can also make go further, offering advantages in both capital and operational expenditures. Adding 802.11n access points to the network can be less expensive than adding more controllers, and can actually result in significant savings since access points with greater intelligence can reduce the number of controllers needed.
Since capital expenditures are largely a function of the number of access points and controllers plus the cost of the sensors, distributed network intelligence offers certain CapEx advantages when combined with 802.11n performance. For one thing, it requires a much lower controller-to-access point ratio, with higher power access points covering a greater area.
Now with distributed traffic management, a single controller can oversee up to eight times the number of access points. This frees up controllers to focus on large scale network and policy management as well as other services, resulting in a more efficient architecture. Access points with built-in sensors for security and troubleshooting can also eliminate extra installation and power costs that would come with a separate sensor network.
By allowing controllers to scale more, networks with distributed intelligence enable real-time troubleshooting and spectral analysis for greater survivability and reduced maintenance costs. The best distributed intelligence solutions will even factor in power consumption as a cost-saving feature, optimizing the power draw of access points to fall below the 13W maximum typical of Power over Ethernet solutions to avoid upgrades.
It also leverages these efficiencies for savings in operational expenditures since, without the right tools, OpEx can easily outpace CapEx within five years. To deliver OpEx advantages, network architecture must use distributed intelligence to address either the cost of repairs or the cost of downtime to an organization.
For instance, now that access points themselves are smart enough to be virtual LAN (VLAN)-aware, it is not necessary to re-engineer the network's VLANs in order to add them in. Moreover, access points that distribute intelligence throughout the network greatly facilitate remote troubleshooting and advanced self-healing. Such features help deliver optimal 802.11n performance, since WLAN architecture that's not smart enough to fix itself when problems arise drives up support costs. The only alternative is to send technicians on-site for each intervention, which can be very expensive for distributed organizations.
In short, the future of wireless network architecture relies on distributed intelligence that meets the performance demands of the new wireless world without compromising security or QoS. The advantages of the centralized hub-and-spoke architecture helped bring more cost-effective 802.11b/g solutions to organizations. But with increased network traffic creating bottlenecks at the controller and an unreliable user experience, the industry is clearly moving toward a more distributed model to reap the full benefits of what 802.11n has to offer.
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