3Com OfficeConnect 3CRWE454A72 Technical Brief page 3

3 C O M ® C O N F I G U R I N G A W I R E L E S S D I S T R I B U T I O N S Y S T E M T E C H N I C A L B R I E F
Figure 3: Wireless Repeater Configuration
If, for example, an 802.3 Ethernet
frame is sent from a wired Station 1
(Sta1) to Sta3 in Figure 2, frame trans-
lations are required while the frame
forwards through the WDS link
between AP1 and AP2. When AP1
receives the 802.3 frame, the frame is
translated to a IEEE 802.11 standard
four-address format frame before it is
sent to a WDS link. In the four-
address format frame, the MAC
address of Sta1, MAC address of AP1,
MAC address of AP2 and MAC
address of Sta3 are all included in the
Wireless Repeater
In Figure 3, AP2 is used to extend the
range of the wireless infrastructure by
forwarding traffic between associated
wireless stations and another repeater
or AP connected to the wired LAN.
Note that the local Ethernet traffic is
not forwarded in this mode. Traffic
between Sta3 and Sta4 is not for-
warded across the WDS link, nor is
traffic between Sta5 and Sta6. As
with a wireless bridge mode, APs
operating in wireless repeater mode
need to translate frames into different
frame formats when forwarding
802.11 frame header, and the frame
data is same as the original Ethernet
frame. Based on information in this
four-address format frame, AP2 will
reconstruct the 802.3 Ethernet frame
when the frame is forwarded to
LAN2. If a security algorithm is con-
figured on the APs, AP1(AP2) will
encrypt(decrypt) this four-address
format frame before frame forward-
ing. From Sta3's point of view, the
bridging function is transparent; i.e.,
the received frame is the same as if
Sta1 and Sta3 resided on the same LAN.
802.3 Ethernet frame
802.11 three-address format frame
802.11 four-address format frame
WDS link
frames between wireless connections
and WDS links; the 802.11 three-address
frame format is used on wireless links
connected to wireless stations, while
the 802.3 four-address frame format is
used on WDS links connected to
other access points. Encryption/
decryption algorithms are also invoked
if the AP is configured to be secure.
The OfficeConnect Wireless 11a/b/g
Access Point can function as a wireless
repeater or wireless bridge if WDS
links are configured between the con-
nected AP pairs appropriately.
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