WESM zl Management and Configuration Guide WT.01.28 and greater

9-11
Fast Layer 2 Roaming and Layer 3 Mobility
Overview
■ When a WLAN enforces Web-Auth, you must configure a redundancy group for
seamless Layer 2 roaming between RPs on different modules. See Chapter 10:
“Redundancy Groups” to learn how to create such a group.
■ You must configure a Layer 3 mobility domain for Layer 3 roaming. Layer 3
roaming is seamless, but not fast. See “Configuring Layer 3 Mobility” on
page 9-15.
In some networks, you must enable Layer 2 roaming between some Wireless Edge
Services zl Modules and Layer 3 roaming between others. Keep these rules in mind
as you plan relationships between Layer 3 mobility domains and redundancy groups:
■ A Layer 3 mobility domain can include multiple redundancy groups or no
redundancy groups at all.
You can divide a Layer 3 mobility domain into multiple redundancy groups, or
you can place all modules in the domain in the same group. Although modules
in the same redundancy group usually map a WLAN to the same VLAN, as long
as you place the modules in the same Layer 3 mobility domain, this is not a
requirement. Roaming behavior is not typically affected by how you group
modules into redundancy groups.
■ Best practices dictate that two Wireless Edge Services zl Modules in the same
redundancy group either be in the same Layer 3 mobility domain or in no
mobility domain at all (for a network that does not require Layer 3 roaming).
In other words, a Layer 3 mobility domain can include members in multiple redun-
dancy groups, but a redundancy group can include members in at most one Layer 3
mobility domain.