WESM zl Management and Configuration Guide WT.01.XX 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 Mobil-
ity” 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
redundancy groups, but a redundancy group can include members in at most
one Layer 3 mobility domain.