ATM Configuration and Troubleshooting Guide

Configuring LAN Emulation Interfaces
Summary of LAN Emulation
Chapter 442
LAN Emulation Connection Types
LAN Emulation components communicate with each other using a series
of ATM connections. LECs maintain separate connections for data
transmission and control traffic.
The control connections are as follows:
• Configuration Direct VCC. This is a bidirectional point-to-point VCC
set up by the LEC to the LECS.
• Control Direct VCC. This is a bidirectional VCC set up by the LEC to
the LES.
• Control Distribute VCC. This is a unidirectional VCC set up from the
LES back to the LEC. This is typically a point-to-multipoint
connection.
The Control Direct VCC and Control Distribute VCCs are permanent
connections.
The data connections are as follows:
• Data Direct VCC. This is a bidirectional point-to-point VCC setup
between two LECs that want to exchange data.
• Multicast Send VCC. This a bidirectional VCC set up by the LEC to
the BUS.
• Multicast Forward VCC. This is a unidirectional VCC set up to the
LEC from the BUS. This is typically a point-to-multipoint
connection, with each LEC as a leaf.
The Multicast Send VCC and Multicast Forward VCCs are permanent
connections.
How an Emulated LAN Works
An emulated LAN works in three stages:
1. Initialization and configuration. Upon initialization, the LEC
must obtain its own ATM address, typically by address registration
performed using ILMI. The LEC then sets up a Configuration Direct
connection to the LECS. To do this, the LEC must first find the
location of the LECS by any of the following: