Avaya Configuring ATM Services Uživatelský manuál stáhnout pdf (Strana 241)

ATM LAN Emulation Overview

B-3

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 it obtains the ATM address of the LE client, the LES also obtains the

physical location of the LE client (from the MAC address or route descriptor).

Having both the ATM addresses and the physical locations of all LE clients on the

emulated LAN allows the LES to coordinate access among LE clients. In other

words, other LE clients query the LES to obtain the ATM address associated with

a speciﬁc MAC address or a route descriptor. After an LE client receives the ATM

address of the LE client it wants to reach, the individual clients communicate

directly.

Broadcast and Unknown Server

To emulate a traditional LAN, the emulated LAN must provide the connectionless

data delivery characteristics of a shared network to its LE clients. This means that

the emulated LAN must also be able to handle broadcast and multicast data. The

broadcast and unknown server (BUS) addresses this requirement by distributing

all broadcast, multicast, and unknown trafﬁc to and from all LE clients on an

emulated LAN.

For example, when an LE client sets up its initial conﬁguration, it obtains the

MAC address of the BUS from the LES. Using this MAC address, the LE client

sets up a multicast send VCC to the BUS. In turn, the BUS registers the LE client

as part of its emulated LAN.

To broadcast data, an LE client uses the multicast send VCC to send information

to the BUS. The BUS then retransmits the data, through multiple point-to-point

connections or one point-to-multipoint connection, to each LE client on the

emulated LAN.

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Avaya Configuring ATM Services Uživatelský manuál Strana 241