Lane Services In The Corebuilder 7000 Family Atm Switch Card; Redundant Lane Services; Lecs Redundancy Facility - Configuring The Lecs-Order Database - 3Com CoreBuilder 7000 Operation Manual

154 C 7: LAN E
HAPTER
LANE Services in the
CoreBuilder 7000
Family ATM Switch
Card
Redundant LANE
Services
LECS Redundancy
Facility - Configuring
the LECS-Order
Database
V 1.0
MULATION ERSIONS AND
As discussed in previous sections, the LAN Emulation services provided by
a CoreBuilder 7000 family ATM switch card are:


LAN Emulation Configuration Server (LECS) — Each CoreBuilder 7000
family ATM switch has a resident LECS which can be enabled or
disabled 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 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 which are resident in
other switches in the network.


LAN Emulation Server/Broadcast and Unknown Server (LES/BUS) —
Each CoreBuilder 7000 family ATM switch card has 16 resident LESs.
The job of the LES in an ELAN is to provide addressing information to
LECs that wish to communicate over the ELAN.
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
7000 switches or failure of the physical links connecting 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
back up LECS and LESs in other CoreBuilder 7000 switches in the
network. The LECS redundancy and the LES redundancy are handled by
two separate mechanisms:


LECS Redundancy Facility


LES Redundancy Facility
You provide for LECS redundancy by enabling the LECS in up to five
CoreBuilder 7000 switches in the network. A LECS-order database with
up to five entries is provided in each switch to support LECS redundancy.
The first entry is the normally active LECS and the others are redundant
backup LECS, activated according to order. When you plan out the
network, you decide which LECS you want to be active and you put it in
the first position in the LECS-order database in each switch in the
network.
Normally, only one LECS of the five is active in the network at any time,
fulfilling the LECs join requests. Should the switch unit containing the
active LECS fail, the next redundant LECS in the LECS-order database is
2.0