Figure 41. L3 Roaming Example - D-Link Unified Access System DWS-3000 Series User Manual

D-Link Unified Access System User Manual
different IP subnets. This feature is especially useful for environments that use wireless Voice
over IP (VoIP) on the 802.11 networks with multiple subnets.
Without IP tunneling, when a wireless client roams between APs that are on different subnets,
the client's IP address changes and the IP connections are dropped. When the IP connection
drops, time-sensitive traffic, such as voice, is affected. L3 roaming allows the client to
continue using the same IP address even when roaming among different subnets.
You can enable L3 tunnels so that the wireless client appears to stay in the same subnet
regardless of which AP it associates with. Every AP that the client associates with must have a
network with the same SSID, network IP, and subnet mask, and L3 tunnels must be enabled on
this network. When the wireless client connects to this network (SSID), all traffic is
encapsulated with this network information and tunneled through various subnets.
You can also use L3 tunnels as a mechanism for aggregating data traffic into the wireless
switch. This allows QoS characteristics, such as access control lists and DiffServ to be
configured in a single place on the wireless switch rather than on individual access points or
edge switches. For more information about QoS, see
If you enable L3 tunnels, we recommend that you enable and configure a separate VAP for
clients that need to use this feature. Configure clients that need L3 Tunneling to connect to the
SSID with L3 tunnels enabled, but configure all other wireless clients to use the VAP with L3
tunnels disabled.
In general, only clients that transmit and receive time-sensitive data while roaming need to
take advantage of this feature.
a D-Link WLAN Controller Switch. The APs and switch are all on different subnets.

Figure 41. L3 Roaming Example

92 © 2001- 2006 D-Link Corporation/D-Link Systems, Inc. All Rights Reserved.
Figure 41
Associated With:
AP1
SSID: VoIP Network
IP: 192.168.100.51
Associated With:
AP1
SSID: Company WLAN
IP: 192.168.20.20
Associated With:
AP2
SSID: Guest Network
IP: 192.168.30.11
"Configuring QoS"
shows a network with two APs that are controlled by
AP1
3 VAPs
SSID - Guest Network
SSID - Company WLAN
SSID - VoIP Network
AP2
3 VAPs:
SSID - Guest Network
SSID - Company WLAN
SSID - VoIP Network
Associated With:
AP2
SSID: VoIP Network
IP: 192.168.100.52
on page 156.
Wireless Controller
Switch