3Com CoreBuilder 9000, User Manual

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392 C
HAPTER
15: LAN E
MULATION
LANE Services in the
CoreBuilder 9000
ATM Switch Fabric
Module
As discussed in previous sections, the LAN Emulation services provided by
a CoreBuilder 9000 ATM Enterprise Switch Fabric Module are:
LAN Emulation Configuration Server (LECS) — Each CoreBuilder 9000
ATM Enterprise Switch has a resident LECS that you enable or disable
through the LMA of the switch. The primary task of the LECS is to
assist a LAN Emulation Client (LEC) to join the Emulated LAN (ELAN) of
its choice. For this purpose, a LECS maintains a database of all ELANs
defined on the network domain that are accessible by the LECS. This
topology database of a LECS includes the ELANs that are resident in
the same switch as the LECS as well as ELANs that are on other
switches in the network.
LAN Emulation Server/Broadcast and Unknown Server (LES/BUS) —
Each CoreBuilder 9000 ATM Enterprise Switch Fabric Module has 16
resident LESs. The job of the LES in an ELAN is to provide addressing
information to LECs that want to communicate over the ELAN.
Redundant LANE
Services
The purpose of LANE redundancy is to ensure the continued operation of
the network ELANs in case of failure of one or more of the
CoreBuilder 9000 ATM Enterprise Switches or failure of the physical links
that connect them. The system ensures that the LANE services that were
provided by the LECS and LESs of the failed switch are efficiently and
reliably transferred to backup LECS and LESs in other CoreBuilder 9000
ATM Enterprise Switches in the network.
The LECS redundancy and the LES redundancy are handled by two
separate mechanisms:
LECS Redundancy Facility
LES Redundancy Facility