Layer-3 Mobility; Overview - Dell PowerConnect W-IAP3WN User Manual

W-IAPs form a single W-Instant network when they are in the same L2 domain. As the number of
clients increase, multiple subnets are required to avoid broadcast overhead. In such a scenario, a
client should be allowed to roam away from the W-Instant network to which it first connected
(home network) to another W-Instant network supporting the same WLAN access parameters
(foreign network) and continue its existing sessions.
Layer-3 mobility allows a client to roam without losing its IP address and sessions. If WLAN access
parameters are same across these networks, clients connected to APs in a given W-Instant network
can roam to APs in a foreign W-Instant network and continue their existing sessions. Clients
roaming across these networks are able to continue using their IP addresses after roaming. You can
configure a list of Virtual Controller IP addresses across which L3 mobility is supported.

Overview

Dell W-Instant Layer-3 mobility solution defines a Mobility Domain as a set of Instant networks,
with same WLAN access parameters, across which client roaming is supported. The W-Instant
network to which the client first connects is called its home network. When the client roams to a
foreign network, an AP in the home network (home AP) anchors all traffic to or from this client.
The AP to which the client is connected in the foreign network (foreign AP) tunnels all client
traffic to or from the home AP through a GRE tunnel.
- Routing of traffic when the client is away from its home network
Figure 67
When a client first connects to an W-Instant network, a message is sent to all configured Virtual
Controller IP addresses to see if this is an L3 roamed client. On receiving an acknowledgement
from any of the configured Virtual Controller IP addresses, the client is identified as an L3 roamed
Dell PowerConnect W-Series Instant Access Point
Chapter 6

Layer-3 Mobility

6.2.0.0-3.2.0.0 | User Guide 91 | Layer-3 Mobility