It’s been a long time since I wrote regarding Cisco Wireless technologies, and since my newest CCNA Wireless book is about to hit the shelves next week, as well as Cisco soon to be released Borderless Mobility networks, I thought I’d write a post regarding the benefits regarding the current Cisco enterprise solutions for your wireless networks.
There are basically two types of wireless networks you can install today: stand-alone (also called autonomous, and Cisco uses the two words interchangeably depending on what day of the week it is), and lightweight (controller based) solutions. The controller based solutions are becoming the defacto standard for all manufacturers today, but autonomous solutions are still available, and this solutions can be found in Cisco’s Linksys products.
If you have an autonomous solution, you have a wireless network as shown in this figure:
Autonomous APs have their own internetworking operating system (IOS). You configure them individually, and there’s no centralized administration point, as pictured. By contrast, the CUWN lightweight model solution definitely requires centralized control, which is gained via Cisco WLAN controllers ( WLCs). APs are controlled and monitored by the WLC, and al All clients and APs transmit information back to the WLC, including stats about coverage, interference, and even client data—back to the WLC as shown in the following figure:
Although the controller based solution is more expensive, the benefits can outweigh the costs because the administrative overhead can reduced. However, if you only have three or four access-points, the costs may not justify the need for a controller, depends on your needs.
All transmitted data is sent between the APs and the WLCs via an encapsulation protocol called Lightweight Access Point Protocol (LWAPP). LWAPP carries and encapsulates control information between the APs and the WLC over an encrypted tunnel. Client data is encapsulated with an LWAPP header that contains vital information about the client’s Received received Signal signal Strength strength Indicator indicator (RSSI) and signal-to-noise ratio (SNR). Once the data has arrived at the WLC, it can be forwarded as needed, which is how the real-time processes actually become available. A couple of great benefits gained through this kind of centralized control are improved security and traffic conditioning.
The controller considers a number of RF characteristics in real time to efficiently handle channel assignments. These include the following:
-Access point received energy
The WLC can digest all this information and through the use of algorithms make decisions on the behalf of the entire system.
Another great benefit about lightweight architecture is that it allows for the splitting of 802.11 Data Link layer functions between the Lightweight AP and the WLC. The Lightweight AP handles real-time portions of the communication, and the Cisco WLC handles the items that aren’t time-sensitive. This technology is typically referred to as split MAC.
One last thing I want to mention: Cisco’s Radio Resource Management (RRM) engine is the component of the WLC that makes the magic of RF environment management possible. Through the use of dynamic algorithms, the WLC creates an environment that is completely self-configuring, self-optimizing, and self-healing. The RRM performs these functions:
• Radio resource monitoring
• Client and network load balancing
• Dynamic channel assignment
• Coverage hole detection and correction
• Dynamic transmit power control
• Interference detection and avoidance
By receiving information constantly from the APs under its control, the WLC maintains a broad and comprehensive view of the RF environment.
That’s it for now, I’ll be back shortly to blog about Cisco’s new up and coming Borderless Mobility with the new CUWN Clean-Air Technology.
In the meantime, be sure and check out http://www.globalnettraining.com/ for some really sweet specials (including my CCNA Wireless class!) and where you can find the best and only Todd Lammle Cisco Authorized training.