LAN Emulation Parameter Group

LAN Emulation, standardized by the ATM Forum's LAN Emulation 1.0 specification, is another way of providing TCP/IP and UDP/IP support over an ATM interface. Address resolution information is provided by a series of LAN Emulation services. When a LAN Emulation interface is brought up, it must register with these LAN Emulation services (known as "joining the LAN"). This registration process and the address resolution process are described in "LAN Emulation".

Unlike Classical IP, the LAN Emulation protocol provides a broadcast service to the upper layer protocols. Therefore, the multicast and RIP limitations described in "Classical IP Parameter Group", do not affect LAN Emulation interfaces.

The SunATM software allows a single ATM interface to join up to sixteen emulated local area networks (ELANs), provided that this action is allowed by the switch and LAN Emulation (LANE) services. Each ELAN joined is represented by a unique lane instance (for example, lane0 or lane1).

A requirement for supporting this feature is that the adapter card be assigned multiple MAC addresses, which the SunATM/S 2.1 and SunATM/P 3.0 adapters support. This feature does not work with the older SunATM/S 2.0 adapters. Use the atmgetmac(1M) command with the count option to find the number of MAC addresses assigned to your SunATM adapter.

After you configure LAN Emulation parameters, you are asked to choose an existing (previously configured) LAN Emulation (lane) instance or to create a new one in the LAN Emulation Instance menu. The following is an example of this menu.

The following lane instances are configured on ba0:
        lane0
        lane1
        [C] Create new lane instance
        [D] Delete lane instance

        [P] Previous Menu
        [M] Main Menu
        [X] Exit
        [?] Help

Enter lane instance or option: lane0

Per-Instance LAN Emulation

The Per-Instance LAN Emulation Parameters menu allows you to configure the per-instance LAN Emulation parameters.

Modifying lane0; Current Configuration:
    IP = atm_lane
    ATM = $myaddress
    LECS Present
    LECS_Address = well-known address
    no additional IP hostnames
        [I] Hostname or IP Address
        [L] Local ATM Address
        [C] LECS Present
        [N] No LECS
        [A] LECS ATM Address
        [E] Emulated LAN Name
        [H] Additional Hostnames

        [P] Previous Menu
        [M] Main Menu
        [X] Exit
        [?] Help

Enter Selection:

Hostname or IP Address

If IP traffic runs over a LAN Emulation instance, assign a hostname and corresponding IP address to the instance. If you enter a hostname that appears in the /etc/init/hosts or /etc/init/ipnodes file, or if NIS, NIS+, or DNS is enabled and the hostname is resolvable over it, you are not prompted to enter an IP address. Instead, the resolution is performed automatically. If the hostname cannot be resolved, you are prompted to enter an IP address. If you must enter an IP address, or if the address is only available through NIS, NIS+, or DNS, the SunATM software updates both the /etc/init/hosts and /etc/init/ipnodes files.

A valid hostname is no more than 80 characters. A valid IP address is a set of four decimal numbers in the range of 0 to 255, separated by dots (for example, 149.144.130.9). The preferred form of an IPv6 address is x:x:x:x:x:x:x:x, where x represents the hexidecimal value of the eight 16-bit pieces of the address, for example, 1080:0:0:0:8:800:200c:417A.

Local ATM Address

The local ATM address is the 20-byte ATM address associated with this LAN Emulation instance. See "ATM Address Formats and Variables" for more information about ATM address formats and variables.

Each lane instance must be assigned a unique ATM address. Each SunATM 2.1 or 3.0 adapter has been assigned 16 unique MAC addresses; if you use the variable $myaddress for each lane instance, the SunATM software will automatically distribute those MAC addresses to the lane instances associated with each physical interface.

LECS Indicator

Most LAN Emulation Services include a LAN Emulation Configuration Server (LECS), which is the first server contacted when bringing up a LAN Emulation client. The LECS provides the ATM address of the LAN Emulation Server (LES), as well as other configuration information about the emulated LAN. However, some LAN Emulation services do not include an LECS, and the LES must be contacted directly. With the LECS Indicator parameter, you specify which service should be contacted first in your configuration. The possible values for this parameter are displayed as individual options on the LAN Emulation Instance menu.

If the value of this parameter is no_LECS, you must specify a value for the LES ATM Address parameter.

LECS ATM Address

By default, the SunATM software attempts to obtain the LECS address using ILMI, as specified in the LAN Emulation specification. If this is not successful, the "well-known" ATM address, also specified by the ATM Forum, is used.

If your LECS uses a different ATM address (not the well-known address), and does not make that address available via ILMI, specify it using this parameter. If applicable, any of the ATM address variables described in "ATM Address Formats and Variables" can be used. Use variable $prefix, in particular.

LES ATM Address

This parameter is required if the value of the LECS Indicator parameter is no_LECS. In that case, LECS is not present to provide a a "well-known" address for the LES, so you must specify an ATM address. Any of the SunATM address variables described in Section 5.3.4.3 under "ATM Address Formats and Variables" ($prefix in particular) can be used.

Emulated LAN Name

If multiple Emulated LANs (ELANs) are present, you can enter a character string in the Emulated LAN Name parameter. The LAN Emulation client uses this parameter to tell the LAN Emulation services which ELAN it wishes to join. By default, if a SunATM LAN Emulation client does not specify an ELAN name, it tells the services to assign it to the default (or only) ELAN.

If you have multiple LAN Emulation instances configured on a physical interface, only one instance can join the default (unspecified) ELAN. You must specify an ELAN name for all other instances.

Additional Hostnames

The SunATM software supports logical interfaces in the SunATM LAN Emulation environment. Logical interfaces allow you to assign multiple IP addresses to a single LAN Emulation interface. A logical interface name consists of three parts: the device name (in the case of SunATM LAN Emulation, lane); the major number, which corresponds to the lane instance number; and the minor number, which distinguishes the logical interfaces on a single lane instance. The format of a LAN Emulation logical interface name is laneN:X, where N is the major number and X is the minor number (for example, lane0:2).

The SunATM software associates each logical interface with a unique hostname and IP address. All logical interfaces on a given physical interface are associated with the same ATM and MAC addresses.

The hostname displayed in the LAN Emulation instance menu corresponds to the minor instance 0. The additional IP Address parameter indicates if any additional hostnames are assigned to the instance. Select this parameter to modify or create additional hostnames. You must enter or modify each additional IP hostname in the same manner as other IP hostname and address pairs (see "ATM Address Formats and Variables" for more details), and associate it with a minor number between 0 and 255.