
Configuring ATM and MPLS Services
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LAN Emulation Components
Each ATM domain contains a LAN emulation configuration server (LECS). Each
emulated LAN comprises a group of LAN emulation clients (LECs), a LAN
emulation server (LES), and a broadcast and unknown server (BUS). These
servers provide specific LAN emulation services.
LAN Emulation Configuration Server
The LAN emulation configuration server (LECS) assigns individual LE clients to
different emulated LANs. The LECS does this by giving the client the ATM
address of the LAN emulation server (LES). This method allows you to assign a
client to an emulated LAN based on the client’s physical location (ATM address)
or the identity of a LAN destination it represents.
LAN Emulation Clients
The LAN emulation client (LE client or LEC) is the interface, or virtual portion of
an interface, through which an end station forwards data, resolves addresses, and
provides other control functions. The LE client provides the MAC-level emulated
Ethernet or token ring service interface to the upper-layer protocol. It also controls
the LAN emulation UNI (LUNI) interface when communicating with other
devices on the emulated LAN.
The LE client uses the configuration protocol to obtain information from the
LECS. This protocol allows the LE client to locate the LES and set up a
bidirectional, control direct virtual channel connection. The LE client
automatically obtains all of the necessary configuration data (including the LES
address) from the LECS.
LAN Emulation Server
The LES controls and coordinates LE client access to the emulated LAN. When
an LE client joins an emulated LAN, it registers its ATM address with the LES.
When the LES obtains the ATM address of the LE client, it also obtains the
client’s physical location (from the MAC address or route descriptor).
LE clients query the LES to obtain the ATM address associated with a specific
MAC address or route descriptor. After an LE client receives the ATM address of
the LE client it wants to reach, the individual clients communicate directly.
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