Emulated LAN Connections 12-7
QUnknown traffic
All broadcast, multicast and unknown traffic to and from a LEC passes
through a single BUS.
The BUS also handles ATM connections and manages its distribution
group.
LAN Emulation
Configuration Server
(LECS)
The LECS assigns individual LAN Emulation clients to different emulated
LANs. When a LEC initializes, it establishes connection to the LECS. Based
on its own programming, configuration database and information
provided by clients, it assigns any client which requests configuration
information to a particular emulated LAN service by giving the client the
LES’s ATM address. This method supports the ability to assign a client to
an emulated LAN based on either the physical location (ATM address) or
the identity of a LAN destination which it is representing (ELAN name).
Emulated LAN Connections
Emulated LAN components communicate with each other by means of
VCCs. Control signals and data transmissions are handled by se parate
VCCs: Control VCCs and Data VCCs.
Control VCCs The control VCCs carry control traffic such as LE_ARP requests and
responses. On initialization, control VCCs are established between LEC
and LES (bi-directional control-direct VCC and control-distribute VCC) as
well as a bi-directional configuration VCC between LEC and LECS.
Characteristics of the control VCCs are summarized in the following
table.
Table12-1 Control VCCs
VCC Name From/To Information carried Initialized by Duration
Configuration LEC<==>LECS LEC requests and receives
configuration information
from LECS, including LES
address
LEC While needed
Control-direct LEC<==>LES LEC sends and receives
controls from LES, including
LE_ARP information
LEC Membership of
LEC in ELAN
Control-distribute LES==>LEC LES distributes control traffic
to LECs, including LE_ARP
information
LES Membership of
LEC in ELAN
abtthgde.book Page 7 Tuesday, June 23, 1998 10:29 AM