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LAN Emulation Operation
2-11
BUS Connection
During the BUS Connection stage, the LEC:
1
Sends an LE-ARP (LAN Emulation-Address Resolution Protocol) request
to the LES containing the target MAC address FF-FF-FF-FF-FF-FF
(broadcast MAC address).
The LES returns an LE-ARP response containing the ATM address of the
emulated LAN’s BUS.
2
Establishes connections to the BUS for transmitting and receiving
multicast and unknown unicast traffic.
Data Movement
In the Data Movement stage, the LEC:
■
Sends and receives multicast MAC frames over the connections to
the BUS.
■
Sends and receives unknown unicast MAC frames (unicast MAC
frames for which the corresponding ATM address on the emulated
LAN is unknown) over the connections to the BUS. At the same
time, the LEC conducts an LE-ARP exchange to associate the MAC
address with the ATM address of another station on the
emulated LAN.
■
After a MAC/ATM address binding is resolved using LE-ARP,
establishes a Data Direct VCC to that ATM address. After the Data
Direct VCC is set up between two LECs, a Flush request is sent via
the bus to signal to the receiving LEC to stop sending Data via the
bus and to start sending data over the established Data Direct VCC.
The receiving LEC responds with a Flush response via the bus to
clear the bus channel. Any unicast frames received from the ATM
address from the time the LEC sends out the Flush request until the
time it receives the Flush response are buffered. The buffered frames
are sent out over Data Direct VCC after the LEC receives the Flush
command instead of over the bus.
■
Disconnects a Data Direct VCC that remains idle for a specified
timeout period.