Wireless/Redundant Edge Services xl Module Management and Configuration Guide WS.02.xx and greater

9-2
Fast Layer 2 Roaming and Layer 3 Mobility
Overview
Overview
The type of roaming that your ProCurve Wireless Edge Services xl Modules
support depends on your network topology and module configurations, as
well as on other factors.
This overview has three main purposes:
■ explaining when you can and should configure fast Layer 2 roaming
■ explaining when Layer 3 mobility is required
■ summarizing the configurations required to implement the best possible
roaming behavior in various circumstances
The sections that follow the overview explain how to enable fast Layer 2
roaming and Layer 3 mobility.
Layer 2 Roaming on a Single Wireless Edge Services
xl Module
The Wireless LAN System, with its coordinated AP design, facilitates fast and
seamless roaming between wireless cells. A central device, the Wireless Edge
Services xl Module, controls all security settings and associations with wire-
less stations. The module generates and encrypts 802.11 frames. In other
words, the module functions much like a single, high-capability AP with many
remote radios (the RPs). Therefore, when a station disassociates from one RP
and reassociates with another RP adopted by the same module, the module
already has in place the association, authentication, and encryption keys.
No matter which security options you have enabled on a wireless LAN
(WLAN), a station can quickly roam (under 50 milliseconds) between two RPs
adopted by the same module.
The Wireless Edge Services xl Module also supports 802.11i mechanisms for
speeding roaming in a WLAN that requires Wi-Fi Protected Access (WPA)/
WPA2 with 802.1X. These mechanisms help to speed roaming both between
RPs adopted by the same module and by different modules.