Nortel 450-24t 用户指南

ATM Overview

309978-D Rev 01

D-3

For more information about LANE, refer to the ATM Forum Technical Committee 
LAN Emulation Over ATM Version 1.0 specification.

An emulated LAN (ELAN) is an implementation of a virtual LAN (VLAN) that is 
using the ATM Forum’s LAN emulation (LANE) specification. The ELAN 
comprises a group of ATM-attached devices that are logically analogous to a 
group of LAN stations attached to an IEEE 802.3 or IEEE 802.5 segment.

Multiple ELANs can be configured within an ATM network, and membership in 
an ELAN is independent of where the end system is physically connected. The 
end system can be associated with multiple ELANs.

Because multiple ELANs over a single ATM network are logically independent, a 
broadcast frame that originates from a member of a particular ELAN is distributed 
only to the members of that ELAN.

The shaded blocks in Figure D-1 on page D-2, represent a single ELAN that was 
created by a user on PC1 wanting to communicate with a user on PC2.

For more information about ELANs, refer to the ATM Forum Technical 
Committee LAN Emulation Over ATM Version 1.0 specification.

A LAN emulation client (LEC) is a type of virtual port that performs data 
forwarding, address resolution, and other control functions over ATM when 
attached to a bridge group on the switch. The LEC provides a MAC-level 
emulated Ethernet IEEE 802.3 or IEEE 802.5 service interface to higher-level 
software. The LEC implements an ATM Forum LANE standards-compliant user 
network interface (UNI) when communicating with other LECs within an ELAN 
(see “User-to-Network Interface (UNI) on page D-5).

The BayStack 450-2M3/2S3 MDA implements the ATM Forum’s LEC as a proxy 
for all of the MAC addresses listed in the BayStack 450 switch’s address database. 
The LECs shown in the example in Figure D-1 on page D-2 are proxy LECs.

For more information about LECs, refer to the ATM Forum Technical Committee 
LAN Emulation Over ATM Version 1.0 specification.