The SunATM software implements the client side of the LAN Emulation standard. To use LAN Emulation in an environment, several LAN Emulation services must also exist in the emulated LAN. These services, called the LAN Emulation Configuration Server (LECS), the LAN Emulation Server (LES), and the Broadcast and Unknown Address Server (BUS), are generally provided in an ATM switch. The following sections provide an overview of the functions of these servers.
LAN Emulation Servers
There are three types of LAN Emulation servers. Each type is briefly described in this section.
LAN Emulation Configuration Server
This server is first contacted by a host interface when the host is brought up on the emulated LAN. Its address is generally a
LAN Emulation Server
The second step in joining an emulated LAN is to make a connection to the LAN Emulation Server. After receiving the LES address from the LECS, a host will establish a connection to the LES. The LES may add the host to a
The LES acts as the ATM ARP server. Since IP and ARP work with MAC addresses, an additional address resolution step is required to convert a MAC address to the corresponding ATM address, which is used to make a connection to the target host; this resolution step is provided by the LES.
Broadcast and Unknown Address Server
The final step in joining an emulated LAN is to make a connection to the BUS. The ATM address of the BUS is obtained by sending a LAN Emulation ARP request to the LES for the broadcast address. Once established, this connection is used to send broadcast messages to the BUS, which will add the client to a
70 SunATM 3U CompactPCI Adapter Installation and User’s Guide • February 2001
