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

Table Of Contents
9-8
Fast Layer 2 Roaming and Layer 3 Mobility
Overview
Figure 9-2. Layer 2 and Layer 3 Roaming Domains
Roaming Behavior
This section summarizes which features you must configure on your Wireless
Edge Services xl Modules to enable the best possible roaming behavior in
various circumstances. Keep in mind that this section discusses the behavior
the modules support. Stations’ capabilities also affect roaming. For example,
the stations wireless network interface card (NIC) determines when the
station will actually roam, and the station’s operating system (OS) determines
how long the station holds the IP stack if it loses the radio signal—even
temporarily.
The previous sections have introduced you to different types of roaming,
which are defined briefly as follows:
Fast roaming—A fast roam is under 50 milliseconds. Fast roaming, as a
standard, refers to pre-authentication as specified by 802.11i, which
applies only to WPA/WPA2 with 802.1X. However, other types of roaming
might be under 50 milliseconds. When a roam is described as fast, it also
is assumed to be seamless.