Configuration Syntax

Configuration Syntax

The good news is that, although the theory of LANE is very complex and cumbersome, Cisco has made the configuration very simple. In fact, LANE uses the same configuration syntax across almost the entire product line. In other words, learn how to configure LANE on a Catalyst and you already know how to configure it on a Cisco router or ATM switch.

To configure a Catalyst LANE module, you must first use the session command to open a LANE command prompt. For example, if you currently have a Telnet session into the Catalyst 5000 Supervisor and you want to configure a LANE blade in slot 4, you issue the command in Example 9-2.

Example 9-2 Opening a LANE Command Prompt

This suddenly catapults you to the IOS-style command prompt on the LANE module! That’s right, the LANE module runs the traditional IOS software (although it’s obviously a separate binary image that must be downloaded from CCO). Almost all of the router’s command-line interface (CLI) features you know and love are available:

  • BASH-style command-line recall (using the arrow keys)
  • config term to alter the configuration
  • debug commands
  • copy run start or write mem to save the configuration

Don’t forget the last bullet: unlike the Catalyst Supervisor, you must remember to save the configuration. Forget to do this and you are guaranteed to have a miserable day (or night) after the next power outage!

  • Tip
    Don’t forget to use the copy run start command to save your LANE configuration!

It is easiest to think of the LANE module as an independent device that connects to the Catalyst backplane. In other words, it has its own DRAM and CPU for use while operational. When the Catalyst is powered down, the LANE module uses its own NVRAM to store the configuration and flash to store the operating system.

The Catalyst LANE module can be configured in five simple steps, each of which are detailed in the sections that follow:

  1. Build overhead connections
  2. Build the LES and BUS
  3. Build the LECS
  4. Build the LECs
  5. Add LECS’ NSAP to ATM Switch

Step 1: Build Overhead Connections

LANE makes extensive use of the ATM overhead protocols mentioned earlier in the chapter. Specifically, the LEC must be configured to use signaling and ILMI. Signaling allows the LEC to build the many SVCs required by LANE, whereas ILMI provides address registration and allows the ATM switch to provide the LECS’ (Bouncer’s) NSAP address. Both of these overhead protocols are enabled by creating two ATM PVCs. The basic syntax for the ATM PVC commands is (there are other options available, but they are not relevant to LANE) as follows:

The VCD parameter is used to specify a locally significant Virtual Circuit Descriptor. The IOS uses a unique VCD to track every ATM connection. In the case of PVCs, you must manually specify a unique value. In the case of SVCs, the Catalyst automatically chooses a unique value.

The VPI and VCI parameters are used to specify the Virtual Path Indicator and Virtual Channel Indicator, respectively. Recall that these are the two addressing fields in the 5-byte ATM cell header.

The two PVCs listed in Example 9-3 must exist on every LEC.

Example 9-3 Mandatory PVCs for LECs

The first PVC provides signaling (QSAAL stands for Q.Signaling ATM Adaptation Layer), whereas the second PVC obviously provides ILMI. You are free to use any VCD values you want; however, they must be unique, and the values 1 and 2 are most common.

Be careful not to enter commands in Example 9-4.

Example 9-4 Eliminating a PVC by Mistake

This common mistake results in only one PVC (ILMI) because the VCD numbers are the same.

The best news of all is that Step 1 is not required for Catalyst LANE modules! All Catalyst LANE images since 3.X automatically contain the two overhead PVCs. On the other hand, if you are configuring LANE on a Cisco router, don’t forget to enter these two commands.

  • Tip
    The ATM PVC statements for signaling and ILMI are not required for Catalyst LANE module configuration. However, they are required for LANE configurations on Cisco routers.

Step 2: Build the LES and BUS (Bartender and Gossip)

The first LANE-specific components to be configured are the LES and BUS (you can create the LANE components in any order you want, however, I recommend the order presented here). To allow the components to function more efficiently, Cisco requires the LES and BUS to be co-located on the same device. Therefore, a single command is used to enable both devices:

For example, the configuration in Example 9-5 creates a LES and BUS for the ELAN named ELAN1.

Example 9-5 Creating the LES and BUS for an ELAN

Enter ELAN names carefully—they are case sensitive.

After completing the configuration in Example 9-5, you should be able to view the status of the LES with the show lane server command as demonstrated in Example 9-6.

Example 9-6 Viewing the LES Status

Finally, be sure to make note of the LES’ address on the second to last line (the ATM address: field), it is used in Step 3.

Unless you are using SSRP server redundancy (discussed later), be sure to only configure one LES/BUS for each ELAN.

Step 3: Build the LECS (Bouncer)

Every LANE network requires a single LECS (although redundant LECSs are possible using SSRP). The LECS is configured using a two-step process:

  1. You must build the LECS database.
  2. You must enable the LECS on the major interface.

Building the LECS Database

The LECS database is a table that lists all of the available ELANs and their corresponding LES NSAP addresses. It can also list optional information such as NSAP addresses for security verification and ELAN IDs. To create a basic LECS database, use the lane database command to enter the database configuration mode of the IOS CLI. The following is the syntax for the lane database command:

At this point, you can now enter one line per ELAN. Each line lists the name of the ELAN and the NSAP of the LES for that ELAN using the following syntax (some advanced options have been omitted for simplicity):

Multiple lines are possible if you are using a feature known as SSRP. This option is discussed later.

For example, the commands in Example 9-7 build a database for two ELANs.

Example 9-7 Building a Database for Two ELANS

A common mistake is to configure the NSAP of the LECS in the database (instead of the LES’ NSAP). The LECS doesn’t need to have its own address added to the database (it already knows that), it needs to know the NSAP of the LES. Just remember, the LECS (Bouncer) needs to tell Clients how to reach the LES (Bartender).

  • Tip
    Be certain that you specify the name of the LES, not the LECS, in the LECS database.

Be aware that the capability to edit the LECS database on the ATM device itself is a very useful Cisco-specific feature. Several other leading competitors require you to build the file on a TFTP server using cryptic syntax and then TFTP the file to the ATM device, an awkward process at best.

Enabling the LECS

After you have built the LECS, you can enable the LECS. As discussed earlier, the LECS must run on a major interface because it is a global component that serves the entire network and does not belong to any particular ELAN.

You must enter the two required commands in Example 9-8 to start the LECS.

Example 9-8 Required Commands for Starting the LECS

The lane config database command binds the database built in the previous step to the specified major interface. The complete syntax for this command is as follows:

The lane config auto-config-atm-address command tells the IOS to use the automatic addressing scheme (MAC Address + 3 . 00) discussed earlier. The following is the complete syntax for this command:

Step 4: Build the LECs (Clients)

The fourth step adds LANE Clients to the appropriate subinterfaces. If a single Catalyst LANE module needs to participate in ten ELANs, it requires ten Clients. To create a single client, issue the command in Example 9-9.

Example 9-9 Creating an LEC

The 1 ties VLAN 1 to ELAN1, merging the two into a single broadcast domain.

The following is the complete syntax for the lane client command:

  • Tip
    It is necessary to specify a VLAN number to ELAN name mapping when creating a LEC on a Catalyst LANE module. This is not required when configuring LANE on a Cisco router (by default, they route, not bridge, between the LEC and other interfaces).

Step 5: Add the LECS’ NSAP to ATM Switch

Recall that Cisco devices prefer to have LECs learn the NSAP of the LECS via ILMI. This requires that ATM switches be configured with the LECS’ NSAP address. To do this, enter the following command on the LS1010 (the LS1010 also uses an IOS-style interface):

This is a global command that applies to all ports on the switch. You can obtain the LECS’ address by issuing the show lane config command or the show lane default command on the device functioning as the Configuration Server. This command must be configured on all ATM switches (there is not an automated protocol to disseminate the LECS’ NSAP between ATM switches). The full syntax of the atm lecs-address-default command is as follows:

The sequence-# parameter is used by the SSRP feature discussed later in the chapter.

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