Understanding LAN Emulation Components (231278)

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LANE is a method used to allow traditional LAN clients to communicate in an ATM environment while switching from a legacy network to an ATM infrastructure. Legacy clients can connect to ATM networks and benefit from high performance and scalability, without making any hardware or software changes on the end systems. For this implementation to work, LANE clients must have similar functionality.

On a LAN, frames are tagged with a source MAC and destination MAC address. This same behavior exists with LANE. However, all LANE clients on the same interface have the same MAC address. An ATM address is then assigned to each LANE client for uniqueness. Because ATM LANs meet the speed requirements for legacy LANs, this additional functionality sets the tone for compatibility.

LANE Components

• Broadcast and Unknown Server (BUS)
  The BUS is responsible for address resolution in a LANE environment. Legacy LANs broadcast for data transmissions and address resolution, whereas ATM is connection-oriented. The BUS receives all broadcast and multicast traffic, including ARP requests for unresolved MAC addresses and ATM addresses, which it sends to members of the emulated LAN. It then sends the response to the station that initiated the query.
• LAN Emulation Client (LEC)
  The LANE Client is client software that runs on any node running on the ATM network, including switches, routers, servers, and workstations. LANE clients are capable of initiating connections, forwarding data, and requesting mappings between MAC addresses and ATM addresses.
• LAN Emulation Configuration Server (LECS)
  The LANE Configuration Server is responsible for assigning the LANE client configuration information. The LECS gives the LANE clients the ATM address of the LES that it will use on the (ELAN). The LECS records the names of the ELANs and the corresponding LES addresses.
• LAN Emulation Server (LES)
  The LAN Emulation Server is a depository for a LANE client's MAC-address-to-ATM-address associations on an ELAN. The LES is sometimes the same node as the BUS. If not, the LES gives the LEC the ATM address of the corresponding BUS. When a LEC queries for address resolution, the LES should respond based upon previous registration information.