Technical basics
4.6 MAC-based communication
SCALANCE W780/W740 to IEEE 802.11n Web Based Management
56 Configuration Manual, 08/2018, C79000-G8976-C267-13
Frames sent by the client to the access point always have the MAC address of the WLAN
client as the source MAC address. In the "learning table" of the access point there is
therefore only the MAC address of the WLAN client.
MAC mode "Automatic", "Manual" and "Own"
If the MAC address of a device connected to the client is adopted (Automatic) or is set
manually (Manual), both the MAC-based and the IP-based frames find their destination for
precisely this device. If the MAC address of the Ethernet interface of the WLAN client is used
(Own), the MAC-based and IP-based frames only reach the WLAN client.
The access point checks whether the destination MAC address matches the MAC addresses
of the connected clients. Since a WLAN client can only use a MAC address, communication
at the MAC address level (ISO/OSI layer 2) can be to a maximum of one node downstream
from the client or the client itself.
With IP Mapping, several nodes downstream from a client can be addressed based on the IP
protocol. The IP packets are broken down according to an internal table and forwarded to the
connected devices.
Maximum possible number of Ethernet nodes with layer 2 communication downstream from
the client: 1
Notes on the "Automatic" setting:
● As long as there is no link on the Ethernet interface, the device uses the MAC address of
the Ethernet interface so that it can be reached in this status. In this status, the device
can be found using the Primary Setup Tool and configured with WBM or CLI.
● As soon as there is a link on the Ethernet interface, the device adopts the source MAC
address of the first received frame.
Note
From the moment that the device
adopts another MAC address (manually or
automatically), the device no longer responds to queries of the Primary Setup Tool when
the query is received over the WLAN interface. Queries of the PST over the Ethernet
interface continue to be replied to.
MAC mode "Layer 2 Tunnel"
The WLAN client uses the MAC address of the Ethernet interface for the WLAN interface.
The access point is also informed of the MAC addresses connected to the Ethernet interface
of the WLAN client. This makes it possible to enter the MAC addresses of these devices in
the "learning table" of the access point. The access point can forward MAC-based frames for
the devices downstream from the client to the appropriate client.
In much the same way as with WDS, a separate port is created for the L2T client over which
the Ethernet frames are sent without changing the destination MAC address.
Maximum possible number of Ethernet nodes downstream from the client: 8
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