Cisco Systems RJ-45-to-AUX manual LAN Emulation Configuration Server Lecs, 170

The ultimate goal of the LES is to arrange and control connections with a LEC. This connection is commonly known as a control direct ATM virtual channel connection (VCC). After this connection is established, it will handle address resolution and registration responses.

Note	The LES establishes communication with the LECS and provides verification information for
	LECs attempting to join. The LES does not maintain a constant connection with the BUS.
	The LES only provides each LEC with the ATM address of the BUS for forwarding.

The LANE servers provide the address registration and resolution functions. These functions include collecting address and route descriptor types based on the LANE standard. Let’s take a look at the address resolution process, which is shown in Figure 8.6 and outlined as follows:

Figure 8.6: The LES address resolution process.

1.A workstation connects to a router or ATM switch and performs a physical outbound packet transmission. This example uses the Address Resolution Protocol (ARP) query to try to locate a device on a remote segment.

Note The local router is typically the ATM LEC and provides the circuit for the initial ATM address mapping.

2.The LEC takes an Ethernet frame and assigns an immediate LEC link, which is used to obtain the ATM address identifier needed to establish an ATM connection. If this process is not successful, the LEC must locate a LES.

3.The LES circuit holds the main ATM network address table and returns with the VCI assignment.

LAN Emulation Configuration Server (LECS)

The LECS provides key services such as registration for Integrated Local Management Interface (ILMI) and configuration support for the LES addresses for the corresponding emulated LAN identifiers.

The LECS contains a database of ATM addresses for the LES and BUS pairs for known ELANs. The LEC consults the LECS to determine the LES’s ATM address when it first joins an ELAN.

Note At least one LECS is required per ATM LANE switch cloud.

The LECS has the following functions:

∙Registers the LECS ATM addresses for known ELANs

∙Supplies LECs with LESs’ ATM addresses

∙Provides interfaces to the LEC and the LES

The registration process of the LECS ATM address uses the ILMI functions to connect to the ATM network; this situation usually includes an ATM switch. Support for configurations from the LECS ensures that the correct LES address is supplied to the LEC.

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