Distributed System (Access Points)
- nearly all 802.11 specifications uses a base-station-oriented topology
- 802.11s - specifies a standard for mesh networks
- instead of all nodes being equal, some nodes are allowed to roam
- access points (APs) - are connected to each other by a distributed system
- scanning - technique in selecting an AP involves 4 steps
- the node sends a Probe frame
- all APs within reach replies with a Probe Response frame
- the node selects one of the APs and sends it an Association Request frame
- the AP replies with an Association Response frame
- nodes scans whenever it
- joins the network
- becomes unhappy with current AP
- APs also periodically sends a Beacon frame
- active scanning - node actively searches for AP
- passive scanning - node can change AP based on the Beacon frame simply by sending an Association Request frame back to the AP
APs Type
- Thick AP – handles encryption and overall management of client devices connected to it
- Thin AP – processing of encryption and policy setting occurs in a centralized switch/controller