802.11n: A Survival Guide

Chapter 8. Designing and Installing an 802.11n Network

With planning out of the way, it’s time to get down to the details of network design. Once you are secure in the knowledge of what your network must support, you can run through straightforward project planning to build it. Begin with understanding what it means to extend the access layer of the network out using a wireless link, and then select an appropriate product. Physical installation comes relatively late in the process, followed by basic network monitoring to make sure that the network is meeting your requirements.

Network Architecture for 802.11n

Throughout the evolution of wireless LAN technology, there have been a number of approaches to add the wireless LAN access layer on to an existing wired backbone network. Most approaches share two fundamental attributes:

MAC-layer mobility (also called “layer 2” mobility after the OSI model). 802.11 works by “hiding” the motion of a device from the network backbone. Even though a wireless LAN-equipped device is moving in space, from the perspective of routers and switches, it is remaining on the same broadcast segment out at the edge of the network. Within a single broadcast segment, mobility is easy. A decade ago, providing continuous connectivity across a routed (layer 3) boundary was difficult, but every commercially-available product suitable for use in a large-scale environment has addressed the “subnet roaming” question. Wireless products provide this capability within the ...