ATM Configuration and Troubleshooting Guide

Configuring LAN Emulation Interfaces
Summary of LAN Emulation
Chapter 4 41
interface, which appears to the higher layer software as though a
real physical Ethernet or Token Ring interface is present. The LEC
must register with the LES and BUS associated with the ELAN it
wishes to join before it can participate in it. Each LEC is identified
by a unique ATM address and MAC address.
IMPORTANT HP’s implementation of ATM does not support MPOA for Token Ring
networks. This is because of a lack of MPOA Server (MPS) support
for Token Ring in routers.
Also, HP’s implementation does not support MPOA for secondary
LANs.
• The LAN Emulation Server (LES) implements the control
coordination function for the ELAN, and provides address
registration and address resolution of MAC to ATM addresses. Each
LEC on an ELAN registers its own MAC address with the LES. It
also queries the LES when it wishes to resolve a MAC address to an
ATM address. The LES either responds directly to the client or
forwards the query to other clients so that they can respond. There is
only one LES per ELAN.
• The Broadcast and Unknown Server (BUS) is a multicast server that
handles broadcast, multicast, and theservicing of unknown unicasts.
There is only one BUS per ELAN.
• The LAN Configuration Server (LECS) is responsible for the initial
configuration of the LAN Emulation Clients (LECs). It provides the
LEC with ELAN configuration information, such as the ATM address
of the LES associated with the ELAN it wishes to join. There is
normally only one LECS for an administrative domain. This LECS
contains the configuration information and LES ATM addresses of
all ELANs in that domain.
Note that HP’s ATM adapter software allows you to configure secondary
LAN Emulation Services to eliminate any single point of failure. You can
configure a secondary LECS, LES, and BUS, which take over if the
primary services fail. For more details, see “Configuring Secondary LAN
Emulation Services” on page 113.