ATM Configuration and Troubleshooting Guide

Conﬁguring LAN Emulation Interfaces

Summary of LAN Emulation

Chapter 4 43

• From the network, using ILMI. The LECS ATM address is

automatically retrieved from the network by the LEC, using

ILMI. Note that the HPATM software supports auto-discovery of

the LECS ATM address using ILMI; however, the ATM switch or

LECS might not. In such cases, the LEC is unable to

automatically discover the LECS ATM address, and uses the

LECS well-known ATM address instead (see the next bullet

below).

• Viathe well-known LECS ATMaddress. The well-known address

is a reserved ATM address deﬁned by the ATM Forum to be used

by a LECS as default. The well-known address is as follows:

0x47.0079.00.000000.0000.0000.0000.00a03e000001.00

• Manual conﬁguration of the LECS ATM address. In this case,

you must manually conﬁgure the LEC with the LECS ATM

address.

Once the LEC knows the location of the LECS, it establishes a

Conﬁguration Direct connection to it. When connected, the LECS

provides the LEC with the information necessary to connect to the

ELAN it wishes to join. This information includes the ATM address

of the ELAN’s LES, the type of LAN being emulated, the maximum

packet size, and the name of the ELAN.

2. Registration and address resolution. After obtaining the address

of the LES, the LEC establishes a Control Direct connection to the

LES. The LES then assigns the LEC a unique identiﬁer, and the LEC

then registers its own MAC and ATM addresses with the LES (the

LES maintains a lookup table containing the MAC addresses and

corresponding ATM addresses of all members of the ELAN). At this

point, the LEC has joined the ELAN.

The LES then establishes a Control Distribute connection backto the

LEC. The LEC can now use the Control Direct and Control

Distribute connections to send LAN Emulation ARP (LE_ARP)

requests to the LES and receive replies.

The LEC now sends LE_ARPs to the LES to get the ATM address of

the BUS corresponding to the broadcast MAC address

(FFFFFFFFFFFF). The LEC then establishes a Multicast Send

connection to the BUS. The BUS responds by setting up a Multicast

Forward connection to the LEC.

The LEC is now ready to transfer data.