Mobility And Client Management; Layer-3 Mobility Overview - Siemens SCALANCE W1750D UI Configuration Manual

Mobility and Client Management

29.1

Layer-3 Mobility Overview

APs form a single SCALANCE W network when they are in the same Layer-2 (L2) domain.
As the number of clients increase, multiple subnets are required to avoid broadcast
overhead. In such a scenario, a client must be allowed to roam away from the SCALANCE
W network to which it first connected (home network) to another network supporting the
same WLAN access parameters (foreign network) and continue its existing sessions.
Layer-3 (L3) mobility allows a client to roam without losing its IP address and sessions. If
WLAN access parameters are the same across these networks, clients connected to APs in
a given SCALANCE W network can roam to APs in a foreign SCALANCE W 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 VC IP addresses across
which L3 mobility is supported.
The Layer-3 mobility solution defines a Mobility Domain as a set of SCALANCE W networks,
with the same WLAN access parameters, across which client roaming is supported. The
SCALANCE W 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.
Figure 29-1
When a client first connects to an SCALANCE W network, a message is sent to all
configured VC IP addresses to see if this is an L3 roamed client. On receiving an
SCALANCE W1750D UI
Configuration Manual, 02/2018, C79000-G8976-C451-02
Routing of traffic when the client is away from its home network
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