VLAN #	ELAN Name
1	default
2	VLAN0002
3	VLAN0003
4	VLAN0004
5	VLAN0005
...1005	...VLAN1005

Task	Command
Step 1 Session to the ATM module.	session mod_num
Step 2 Activate the privileged mode on the ATM module.	enable
Step 3 Enter the configuration mode.	configure terminal
Step 4 Enable VTP.	vtp enable
Step 5 Exit the configuration mode.	Ctrl-Z
Step 6 Write the current configuration to NVRAM.	write memory
Step 7 Return to the supervisor console.	exit

Task	Command
Step 1 Activate the privileged mode on the ATM module.	enable
Step 2 Select the ATM interface.	interface atm0
Step 3 Apply output throttling.	atm traffic-shape rate number_between_1-155_indicating_Mbps
Step 4 End the session.	Ctrl-Z

Task	Command
Step 1 Activate the privileged mode on the ATM module.	enable
Step 2 Select the ATM interface.	interface atm0
Step 3 Disable output throttling.	no atm traffic-shape rate number_between_1-155_indicating_Mbps
Step 4 End the session.	Ctrl-Z

VLAN number	ELAN name
1	default
2	VLAN0002
3	VLAN0003
4	VLAN0004

Unspecified Digits	Value Location
Prefix (first 13 bytes)	Switch via ILMI, or configured locally if ILMI is not supported on the switch.
ESI (next 6 bytes)	Slot MAC address¹ plus 0--LANE LEC 1--LANE LES 2--LANE BUS 3--LECS
Selector field (last byte)	Subinterface number, in the range 0 through 255.

Configuring the ATM Module

This chapter describes how to configure the Asynchronous Transfer Mode (ATM) module, which provides connectivity to the ATM backbone. It also describes the configuration of the LAN Emulation (LANE) client and servers.

LANE permits an ATM network to be used as a LAN backbone for hubs, bridges, and Ethernet switches such as the Catalyst 5000 series switches. LANE also allows end stations to communicate through a LAN-to-ATM switch with an ATM-attached device, such as a file server, without requiring the traffic to pass through a more complex device such as a router. LANE requires a switch that supports User-Network Interface (UNI) 3.0 or 3.1 and point-to-multipoint signaling--for example, the Cisco LightStream family of switches.

Note In this software release, Cisco Systems supports only emulated Ethernet LANs. This release of LANE is supported on Catalyst 5000 series switches containing ATM modules and on Cisco routers with ATM interfaces installed.

Accessing the ATM LAN Emulation Module

You can open a session with the ATM module in the Catalyst 5000 series switch by entering the session mod_num command from the supervisor Console> prompt. After opening the session, you see the ATM> prompt. You then have direct access only to the ATM module with which you have established a session.

The ATM module uses a subset of the Cisco IOS software. Generally, the Cisco IOS software works the same on the ATM module as it does on routers. Refer to "Understanding the Command-Line Interfaces," for more information.

Default Configuration

The ATM LANE module has the following default configuration:

The Interim Local Management Interface (ILMI) and signaling permanent virtual connections (PVCs) are set up.
No LANE is configured.
Nonvolatile random-access memory (NVRAM) contains no configuration information.

Customizing the Configuration

To configure the ATM module, you must use configuration mode. To enter configuration mode, enter the EXEC command configure at the privileged EXEC prompt (ATM#). You see the following message, which asks you to specify the terminal, the NVRAM, or a file stored on a network server as the source of configuration commands:

Configuring from terminal, memory, or network [terminal]?

Terminal configuration means changing the run-time configuration. You can save the run-time configuration into the NVRAM. When you configure from memory, the run-time configuration is updated from the NVRAM. When you configure from the network, the run-time configuration is updated from a file in a server on the network.

Note The network method is not available in this software release.

The ATM module accepts one configuration command per line. You can enter as many configuration commands as you want.

You can add comments to a configuration file describing the commands you have entered. Precede a comment with an exclamation point (!) or the pound sign (#). Comments are not stored in NVRAM or in the active copy of the configuration file. In other words, comments do not appear when you list the active configuration with the write terminal EXEC command or list the configuration in NVRAM with the show configuration EXEC command. Comments are stripped out of the configuration file when it is loaded to the ATM module.

Configuring from the Terminal

To configure the ATM module from the terminal, complete these steps:

Task	Command
Step 1 Enter configuration mode, selecting the terminal option.	configure terminal
Step 2 Enter the necessary configuration commands.	Refer to the *Catalyst 5000 Series Command Reference* publication for information about specific commands.
Step 3 Quit configuration mode.	Ctrl-Z
Step 4 Save the configuration file modifications to NVRAM.	write memory

In the following example, the ATM module is configured from the terminal. The interface atm 0 command designates that ATM interface 0 is to be configured. Then the lane client ethernet vlan_num elan-name command links VLAN 1 to the manufacturing (man) emulated LAN (ELAN). The Ctrl-Z command quits configuration mode. The write memory command loads the configuration changes into NVRAM on the ATM module.

ATM# configure terminal
ATM (config)# interface atm 0
ATM (config)# lane client ethernet 1 man
ATM (config)# Ctrl-Z
ATM# write memory

NVRAM stores the current configuration information in text format as configuration commands, recording only nondefault settings. The ATM module software performs a memory checksum to guard against corrupted data.

As part of its startup sequence, the ATM module startup software always checks for configuration information in NVRAM. If NVRAM holds valid configuration commands, the ATM module executes the commands automatically at startup. If the ATM module detects a problem with its NVRAM or the configuration it contains, the module goes into default configuration. Problems can include a bad checksum for the information in NVRAM or the absence of critical configuration information.

Configuring from Nonvolatile Memory

You can configure the ATM module from NVRAM by reexecuting the configuration commands stored in NVRAM. To do so, complete this task in EXEC mode:

Task	Command
Configure the ATM module from NVRAM.	configure memory

After configuring the ATM module, you are ready to implement LANE.

Implementing LANE

This section describes LANE components, prerequisite information, the procedures necessary to implement LANE, and other information about monitoring and maintaining LANE components.

LANE Components

An unlimited number of ELANs can be set up in an ATM cloud. A Catalyst 5000 series switch ATM module can participate in multiple ELANs.

LANE is defined on a client-server LAN model as follows:

LANE Client (LEC)

: An LEC emulates a LAN interface to higher-layer protocols and applications. It forwards data to other LANE components and performs LANE address-resolution functions.
: Each LEC is a member of only one ELAN. However, a router or a Catalyst 5000 series switch ATM module can include LECs for multiple ELANs--one LEC for each member of ELAN.
: If a router has LECs for multiple ELANs, the router can route traffic between the ELANs.

LANE Server (LES)

: The LES for an ELAN is the control center. It provides joining, address resolution, and address registration services to the LECs in that ELAN. LECs can register destination unicast and multicast Media Access Control (MAC) addresses with the LES. The LES also handles LANE Address Resolution Protocol (ARP) (LE ARP) requests and responses.

LANE broadcast-and-unknown server (BUS)

: The LANE BUS sequences and distributes multicast and broadcast packets and handles unicast flooding. At least one combined LES and BUS is required per ELAN.

LANE Configuration Server (LECS)

The LECS contains the database that determines the ELAN to which a device belongs. Each configuration LES can have a differently named database. Each LEC consults the LECS just once--when it first joins an ELAN--to determine which ELAN it should join. The LECS returns the ATM address of the LES for that ELAN.

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

The LECS database can have the following four types of entries:

ELAN_name, ATM_address_of_LES pairs
LEC_MAC_address, ELAN_name pairs
LEC_ATM_template, ELAN_name pairs
Default ELAN name

: ELAN names must be unique on an interface. If two interfaces participate in LANE, the second interface might be in a different switch cloud.

Note Multiple LESs, BUSs, and LECSs can exist for the same ELAN, providing redundancy. For more information, refer to the section "Configuring LES/BUS/LECS Redundancy" in this chapter.

Before You Begin

Before you implement LANE, be aware of the following:

All ATM switches have identical lists of the global LECS addresses with the identical priorities.
The operating LECSs must use exactly the same configuration database. Load the configuration table data by entering the config net command. This method minimizes errors and enables the database to be maintained centrally.
In an underlying ATM network failure, there can be multiple master LECs and multiple active LESs for the same ELAN, yielding a partitioned network. Clients continue to operate normally, but transmission between different partitions of the network is not possible. The system recovers when the network break is repaired.
The LANE subsystem can handle up to 16 LECS addresses.
The number of LESs that can be defined per ELAN is unlimited.
When an LECS switchover occurs, no previously joined clients are affected.
In an LES/BUS switchover, there is a momentary loss of clients until all clients are transferred to the new LES/BUS.
LECSs automatically come up as masters until a higher level LECS tells them otherwise.
When a higher priority LES comes online, it bumps the current LES off the same ELAN. For a short time after a power on, some clients might change from one LES to another, depending upon the order of the LESs coming up.
If none of the specified LESs are up or connected to the master LECS, and more than one LES is defined for an ELAN, the LECS rejects any configuration request for that specific ELAN.
Changes made to the list of LECS addresses on ATM switches can take up to 1 minute to propagate through the network. Changes made to the configuration database regarding LES addresses take effect almost immediately.
If none of the designated LECSs are operational or reachable, the ATM Forum-defined "well- known" LECS address is used.
The LECS to be used can be overridden on any subinterface by entering the following commands:

-- lane auto-config-atm-address

-- lane fixed-config-atm-address

-- lane config-atm-address atm-address-template

: To avoid affecting the LES/BUS/LEC redundancy, do not override any LECS, LES, or BUS addresses.

Prerequisites

Before implementing LANE, perform these tasks:

Create a LANE plan.

Draw up a plan and a worksheet for your own LANE scenario. Determine the LANE components you want to use, their locations, their associated virtual LANs (VLANs), and the necessary redundancy features. Leave space for noting the ATM address of each LANE component on each subinterface of each participating device.

Your plan should include the following information:

The Catalyst 5000 series switch interface where the LANE configuration server will be located
The Catalyst 5000 series switch interface and subinterface where the LANE server and BUS for each ELAN will be located
The Catalyst 5000 series switch ATM modules, subinterfaces, and VLANs where the clients for each ELAN will be located
The name of the default ELAN in the LECS database (optional)

Decide whether to set up one or multiple ELANs. If you set up multiple ELANs, decide where the LES/BUSs and LECs will be located and whether you will restrict the LECs that can belong to each ELAN.

Procedures

Configuring LANE involves the following tasks:

Displaying ATM Addresses

You can display the default ATM addresses for the LECS, LES, BUS, and LEC. Use this information to configure LECS addresses in the ATM switch and to configure the LECS database.

Procedure for Dual PHYs Connected to the Same Switch

To display default ATM addresses, perform the following task:

Task	Command
Display default ATM addresses.	show lane default-atm-addresses

After you enter the show lane default-atm-addresses command, you see the following display:

ATM# show lane default-atm-addresses

interface ATM0:
LANE Client:        47.00918100000000613E5D1101.00400BF00440.**
LANE Server:        47.00918100000000613E5D1101.00400BF00441.**
LANE Bus:           47.00918100000000613E5D1101.00400BF00442.**
LANE Config Server: 47.00918100000000613E5D1101.00400BF00443.00

In this display, ** is the subinterface number byte in hexadecimal. Record the addresses for later use.

Procedure for Dual PHYs Connected to Different Switches

If the two PHYs on the ATM Dual PHY module are connected to different switches, you must determine the addresses to use if the first PHY goes down. Use this procedure:

Task	Command
Step 1 Change the preferred PHY to the one not currently in use.	atm preferred phy {A \| B}
Step 2 Display the default ATM addresses.	show lane default-atm-addresses
Step 3 Determine the active PHY.	show interface

Diagnostics

Ensure that the ATM Dual PHY module is connected to the switch, that the interface is up, and that ILMI PVC is enabled.

This display indicates that the card could not get the ATM prefix through ILMI from the switch.

ATM# show lane default-atm-addresses 
interface ATM0:
LANE Client:        ...00400BF00440.**
LANE Server:        ...00400BF00441.**
LANE Bus:           ...00400BF00442.**
LANE Config Server: ...00400BF00443.00

In this display, ** is the subinterface number byte in hexadecimal.

Displaying the ATM addresses of LESs and LECs as you configure them can save you the time and effort of computing the addresses. These savings can be considerable when you set up the LECS database--especially for ELANs with restricted membership. Make a note of the LECS ATM address so you can configure it on each ATM subinterface where an LES and BUS is configured.

Configuring the LECS ATM Address on a LightStream 1010 ATM Switch

You must program all LECS addresses into each ATM switch, such as a LightStream 1010 switch, that is connected to a participant in your LANE network. Programming the addresses allows the LESs and LECs to determine the LECs addresses dynamically through ILMI.

To configure a server ATM address on a LightStream 1010 ATM switch, perform these steps for each connected LightStream 1010 ATM switch:

Task	Command
Step 1 Enter the configuration mode.	configure terminal
Step 2 Enter the address of the LECS.	atm lecs-address *atm-address*
Step 3 Verify the address entered.	show atm ilmi-configuration

Setting Up the LES/BUS

To set up the LES/BUS for an ELAN, perform these steps beginning in interface configuration mode:

Task	Command
Step 1 Enter the configuration mode.	configure terminal
Step 2 Specify the subinterface for the first ELAN.	interface atm 0. subinterface-number
Step 3 Enable the LES/BUS on the subinterface.	lane server-bus ethernet elan-name
Step 4 Repeat Steps 2 and 3 for all other ELANs on this module.

If the ELAN in Step 2 has restricted membership, you may not want to specify the name at this time to avoid a discrepancy with the ELAN name specified in the LECS database. If you link the LEC to an ELAN in Step 2 and, through some mistake, it does not match the LECS database entry linking the LEC to an ELAN, this LEC will not be allowed to join this, or any other, ELAN.

If you decide to include the name of the ELAN linked to the LEC and later want to associate that LEC with a different ELAN, change the LECS database before you change the LEC on this subinterface.

Setting Up the LECS Database

Complete the steps in this section to set up the LECS database. If you have more than one LECS, make sure that all databases are identical. If you have more than one server in an ELAN, servers take precedence over other servers based on the order in which they are entered into the LECS database. If a Dual PHY module acts as a server, you must enter the predetermined address of each PHY.

Setting Up the LECS Database for the Default ELAN

When you configure a Catalyst 5000 series switch as the LECS for one default ELAN, you provide a name for the database, the ATM address of the LES for the ELAN, and a default name for the ELAN. In addition, you indicate that the LECS ATM address is to be computed automatically.

When you set up a database of only a default, unrestricted ELAN, you do not need to specify where the LANE LECs are located. That is, when you set up the LECS database for a single default ELAN, you do not have to provide any database entries that link the ATM addresses of any LECs with the ELAN name.

To set up the LECS for the default ELAN, complete these steps:

Task	Command
Step 1 Create a named database for the LANE configuration LECS.	lane database database-name
Step 2 In the configuration database, bind the name of the ELAN to the ATM address of the LES.	name elan-name server-atm-address atm-address
Step 3 In the configuration database, provide a default name of the ELAN.	default-name elan-name
Step 4 Exit from database configuration mode and return to global configuration mode.	exit

If you set up only a default ELAN, the elan-name value in Step 2 is the same as the default ELAN name you provide in Step 3. If you use both PHYs on the ATM LANE Dual PHY module, you must use LES/BUS/LECS redundancy.

Setting Up the LECS Database for Unrestricted-Membership ELANs

When you set up a database for unrestricted-membership ELANs, you create database entries that link the name of each ELAN to the ATM address of its LES.

However, you might choose not to specify where the LECs are located. That is, when you set up the LECS database, you do not have to provide any database entries that link the ATM addresses or MAC addresses of any LECs with the ELAN name.

To configure a router as the LECS for multiple ELANs with unrestricted membership, complete these steps, beginning in global configuration mode:

Task	Command
Step 1 Create a named database for the LANE configuration LECS.	lane database database-name
Step 2 In the configuration database, bind the name of the first ELAN name to the ATM address of the LES for that ELAN.	name elan-name1 server-atm-address atm-address
Step 3 In the configuration database, bind the name of the second ELAN to the ATM address of the LES. Repeat this step, providing a different ELAN name and an ATM address for each additional ELAN in this switch cloud.	name elan-name2 server-atm-address atm-address
Step 4 (Optional) Specify a default ELAN for LECs not explicitly bound to an ELAN.	default name elan-name
Step 5 Exit from database configuration mode and return to global configuration mode.	exit

Setting Up the LECS Database for Restricted-Membership ELANs

When you set up the database for restricted-membership ELANs, you create database entries that link the name of each ELAN to the ATM address of its LES.

However, you also must specify where the LECs are located. That is, for each restricted-membership ELAN, you provide a database entry that explicitly links the ATM address or MAC address of each LEC of that ELAN with the name of that ELAN.

Those LEC database entries specify the LECs that are allowed to join the ELAN. When an LEC requests that the LECS indicate which ELAN it is to join, the LECS consults its database and then responds as configured.

When LECs for the same restricted-membership ELAN are located in multiple Catalyst 5000 series ATM modules, each LEC ATM address or MAC address must be linked explicitly with the name of the ELAN. As a result, you must configure as many LEC entries (Step 5 in the following procedure) as you have LECs for ELANs in all the ATM modules of Catalyst 5000 series switches. Of course, each LEC will have a different ATM address in the database entries.

To set up the LECS for ELANs with restricted membership, perform these steps, beginning in global configuration mode:

Task	Command
Step 1 Create a named database for the LECS.	lane database database-name
Step 2 In the configuration database, bind the name of the first ELAN to the ATM address of the LES for that ELAN.	name elan-name1 server-atm-address atm-address restricted
Step 3 In the configuration database, bind the name of the second ELAN to the ATM address of the LES. Repeat this step, providing a different name and a different ATM address for each additional ELAN.	name elan-name2 server-atm-address atm-address [restricted]
Step 4 (Optional) Specify a default ELAN for LECs not explicitly bound to an ELAN.	default name elan-name
Step 5 Add a database entry associating a specific LEC ATM address with a specific restricted-membership ELAN. Repeat this step for each of the LECs of each of the restricted-membership ELANs on this switch cloud, in each case specifying that LEC ATM address and the name of the ELAN with which it is linked.	client-atm-address atm-address name elan-name
Step 6 Exit from database configuration mode and return to global configuration mode.	exit

Note An ELAN named default must be available for VLAN Trunking Protocol (VTP) management.

Starting and Binding the LECS

To start and bind the LECS, perform these steps:

Task	Command
Step 1 Enter the configuration mode.	configure terminal
Step 2 Select the ATM interface.	interface atm0
Step 3 Specify the name of the LECS.	lane config test
Step 4 Specify the address of the LECS.	lane config auto-config-atm-address
Step 5 Bind the interface.	lane config database database-name
Step 6 Exit the configuration mode.	end

Setting up the LECs

On any Catalyst 5000 series switch, you can set up one LEC for one ELAN or multiple LECs for multiple ELANs. You can set up a LEC for a given ELAN on any Catalyst 5000 series switch you choose to have participate in that ELAN. After you set up the interface for the VLAN, you must link the VLAN number with the ELAN name.

To set up only a LEC for an ELAN, perform these steps beginning in interface configuration mode:

Task	Command
Step 1 Specify the subinterface for a VLAN on this switch.	interface atm 0.subinterface-number
Step 2 Enable an LEC for the first ELAN.	lane client ethernet vlan# elan-name

Verifying the Setup

Once you set up the LECs on the subinterfaces of an ATM module, you can display their ATM addresses by completing this task in EXEC mode:

Task	Command
Display the LES, BUS, and LEC ATM addresses.	show lane

The output of this command shows all subinterfaces configured for LANE. For each subinterface, the command displays and labels the ATM addresses that belong to the LES, the BUS, and the LEC.

When you look at each ATM address, note the following:

The prefix is the one you set up on the switch.
The end-system identifier (ESI) field reflects the base address of the pool of MAC addresses assigned to the ATM interface plus a value that represents the specific LANE component.
The selector byte is the same number as the subinterface (converted to hexadecimal).

Repeat the above task on each Catalyst 5000 series switch before you set up the LECs on the next Catalyst 5000 series switch. Print the display or make a note of these ATM addresses so that you can use it when you set up the LECS database.

At this point in the configuration process, the LECs are normally not operational.

Monitoring and Maintaining LANE Components

After configuring LANE components on an interface or any of its subinterfaces, you can display their status on a specified subinterface or on an ELAN. To show LANE information, perform these steps in EXEC mode:

Task	Command
Step 1 Display the global and per-VCC¹ LANE information for all the LANE components and ELANs configured on an interface or any of its subinterfaces.	show lane [interface atm 0 [subinterface-number] \| name elan-name] [brief]
Step 2 Display the global and per-VC² LANE information for the BUS configured on any subinterface or ELAN.	show lane bus [interface atm 0 [subinterface-number] \| name elan-name] [brief]
Step 3 Display the global and per-VC LANE information for all LECs configured on any subinterface or ELAN.	show lane client [interface atm 0 [subinterface-number] \| name elan-name] [brief]
Step 4 Display the global and per-VC LANE information for the LECS configured on any interface.	show lane config [interface atm 0]
Step 5 Display the LECS database.	show lane database [database-name]
Step 6 Display the LANE ARP table of the LECs configured on the specified subinterface or ELAN.	show lane le-arp [interface atm 0 [subinterface-number] \| name elan-name]
Step 7 Display the global and per-VC LANE information for the LES configured on a specified subinterface or ELAN.	show lane server [interface atm 0 [subinterface-number] \| name elan-name] [brief]

¹ VCC = virtual channel connection
² VC = virtual channel

Configuring Specialized LANE Features

To configure specialized LANE features, perform the appropriate tasks in this section.

Configuring LES/BUS/LECS Redundancy

LES/BUS/LECS redundancy allows you to configure redundant LESs and BUSs so that the LECs in an ELAN can automatically switch to a backup LES if the primary LES fails. The priority of the LES/BUS pairs is established by the order in which they are entered in the LECS database.

The LANE protocol does not specify where any of the ELAN server entities should be located, but for the purpose of reliability and performance, Cisco implements these server components on its routers and LAN switches.

With Phase I LANE, only one LECS, capable of serving multiple ELANs, and only one LES per ELAN could exist for an ATM cloud. The Phase I LANE protocol did not allow for multiple LESs within an ELAN. Therefore, these components represented both single points of failure and potential bottlenecks for LANE service.

LANE LES/BUS/LECS redundancy corrects these limitations by allowing backup LECS and LES servers for an ELAN. LANE LES/BUS/LECS redundancy is always enabled. You can use this redundancy feature by configuring multiple servers.

LES/BUS/LECS redundancy works only with Cisco LECS and LES combinations. Third party LANE components continue to interoperate with the LECS and LES function of Cisco routers but cannot take advantage of the redundancy features.

The following three servers are single points of failure in the ATM LAN Emulation System:

LECS (configuration server)
LES (ELAN server)
BUS

LES/BUS/LEC redundancy eliminates these single points of failure. To configure LES/BUS/LECS redundancy, use the procedure in the following section.

Procedure

To enable redundant LECSs, enter the multiple LECS addresses to the end ATM switches, which are used as central locations for the list of LECS addresses. After entering the LECS addresses, LANE components connected to the switches can obtain the global list of LECS addresses.

Note To configure LES/BUS/LECS redundancy, you must enable multiple/redundant/standby LECSs and multiple/redundant/standby LES/BUSs. Cisco Systems' LANE technology operates seamlessly with other vendor LANE components, although LES/BUS/LECS redundancy is not effective in this situation. The LES/BUS/LEC redundancy configuration procedure guards against hardware failure on which LANE components are running, including all Catalyst 5000 series switches. The configuration procedure is not effective for ATM network switch failures.

To enable LES/BUS/LEC redundancy, complete these steps:

Task	Command
Step 1 On the ATM switch, enter all the multiple LECS addresses.	set configserver index.address mask (for the Cisco LightStream 100) atm lecs-address `address` (for the Cisco LightStream 1010)
Step 2 On the ATM module, specify redundant LES/BUSs. Enter the command for each LES address on the ELAN.	name *elan-name* server-atm-address *les-address*

The index determines the priority; 0 is the highest priority.

Configuring VTP

When VLANs are added to a Catalyst 5000 series switch in a management domain, VTP automatically distributes information to other trunks of all of the devices in the domain. The VTP is transmitted on all trunk connections, including Inter-Switch Link (ISL), IEEE 802.10, and LANE. VTP is disabled by default on the Catalyst 5000 series switch ATM module and must be explicitly enabled. VTP works only with Catalyst 5000 series software release 2.1 or later and ATM software release 3.1 or later.

Setting Up an LEC Using VTP

VTP running on the Catalyst 5000 series supervisor module allows you to set up VLAN-to-LEC/ELAN mapping and establish LECs on the ATM module.

Procedure

You can create an LEC on each ATM module in every Catalyst 5000 series switch in a VTP domain. To set up an LEC for VLAN 1, perform these steps:

Task	Command
Step 1 Enable VTP.¹	session mod_num enable configure terminal vtp enable Ctrl-Z write memory exit
Step 2 From the supervisor module, create an LEC on each ATM module of all Catalyst 5000 series switches on a specified VTP domain.	set vlan vlan_num name elan_name²

¹ Refer to the section "Setting Up VTP."
² The elan_name variable for VLAN 1 must be set to default.

The name default in the set vlan command is the ELAN name for VLAN 1. The value vlan_num represents the VLAN number to configure, and elan_name is the name of the ELAN.

You can use VTP to set up an LEC in either transparent or nontransparent mode. When VTP is enabled and your switch is in transparent mode, entering the set vlan vlan_num [name elan_name] command creates LECs on all ATM modules of only the switch on which you entered the command.

In nontransparent mode, the set vlan vlan_num [name elan_name] command entered from the supervisor module of any Catalyst 5000 series switch automatically creates an LEC for that VLAN/ELAN-name pair on all ATM modules on Catalyst 5000 series switches in that VTP domain.

To find your current mode and domain, enter the show vtp domain command.

Setting Up VTP

When you set up an LEC using VTP, these prerequisites apply:

Make sure you properly configure the LECS/LES/BUS using the ATM module command-line interface (CLI) for each VLAN before creating an LEC. VTP sets up only LECs. It does not set up the LECS/LES/BUS.
You can change all ELAN names with the exception of VLAN 1, whose ELAN name must remain default. You cannot override the ELAN name for VLAN 1 (default) by using the [name elan_name] parameter. You can assign all other VLANs any name.

: When you enter the set vlan vlan_num [name elan_name] command in transparent mode and do not specify the optional name elan_name, the software uses the following names by default:

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