IBM ATM OC-3c manual LAN Emulation Components, LAN Emulation Client LEC, LAN Emulation Server LES

LAN Emulation Components

Each Emulated LAN (ELAN) is composed of a set of LAN Emulation components. This section describes each of these components.

LAN Emulation Client (LEC)

Each ATM device has a number of LAN Emulation clients. Each LAN Emulation Client (LEC) is responsible for taking Ethernet frames and passing them through the ATM network to the LEC serving the destination address. The destination LEC is responsible for receiving the frame from the ATM network and passing it to the local Ethernet network, where it can be delivered to the destination address.

LAN Emulation Server (LES)

Each LAN Emulation Server (LES) controls a single Emulated LAN (ELAN). The purpose of the LES is to store address and control information for the ELAN it is serving, and to pass this information onto the clients and other components within the ELAN.

The LES, therefore, needs to know the address of every client and component in the ELAN.

What is LAN Emulation (LANE)? 2-3

Broadcast and Unknown Server (BUS)

Each ELAN has a Broadcast and Unknown Server (BUS). The BUS forwards frames that it receives from any client to all of the clients in the ELAN. The BUS is used to forward broadcast and multicast frames so that they are flooded throughout the ELAN. The BUS also floods unicast frames if the location of the destination MAC address is unknown.

LAN Emulation Configuration Server (LECS)

The LAN Emulation Configuration Server (LECS) is an optional component, and is not essential for the normal running of an ELAN.

The LECS stores the names of all the ELANs that have been set up on the ATM network, and the address of the LAN Emulation Server (LES) that serves each of these ELANs.

If there is an LECS on the network, any client can interrogate the LECS to find the address of the server associated with the ELAN they wish to join. The clients may also get ELAN configuration information from the LECS.

If a LECS is not present on the ATM network, the server address to be used by the client must be specified using the management software on that client’s ATM device.