User Manual Part 2

Wi-Fi Array
270 Configuring the Wi-Fi Array
Understanding Fast Roaming
To maintain sessions for real-time data traffic, such as voice and video, users must
be able to maintain the same IP address through the entire session. With
traditional networks, if a user crosses VLAN or subnet boundaries (i.e., roaming
between domains), a new IP address must be obtained.
Mobile Wi-Fi users are likely to cross multiple roaming domains during a single
session (especially wireless users of VoIP phones). Layer 3 roaming allows a user
to maintain the same IP address through an entire real-time data session. The user
may be associated to any of the VLANs defined on the Array. The Layer 3 session
is maintained by establishing a tunnel back to the originating Array. You should
decide whether or not to use Layer 3 roaming based on your wired network
design. Layer 3 roaming incurs extra overhead and may result in additional traffic
delays.
Fast Roaming is configured on two pages. To enable the fast roaming options that
you want to make available on your Array, see Step 19 to Step 21 in “Global
Settings (IAP)” on page 277. To choose which of the enabled options are used by
an SSID or Group, see “Procedure for Managing SSIDs” on page 249 (Step 13) or
“Procedure for Managing Groups” on page 264.