Cisco Catalyst 5000, WS-X5161, WS-5167, WS-X5162, WS-X5168 Series Manual

Configuring Token Ring LAN Emulation

Last Updated: December 4, 2012

This chapter describes how to configure Token Ring LAN emulation (LANE) on the Catalyst 5000
platform. This feature is supported on the following Catalyst 5000 series ATM modules:

• ATM Dual PHY OC-12 modules (WS-X5161 and WS-X5162)

• ATM Dual OC-3 modules (WS-5167 and WS-X5168)

Support for the Token Ring LANE feature was first introduced in Cisco IOS Release 12.0(7)T.

Note

Beginning with Cisco IOS Release 11.3, all commands supported on the Cisco 7500 series routers are also
supported on the Cisco 7000 series.

For a complete description of the commands in this chapter, refer to the the
Command Reference. To locate documentation of other commands that appear in this chapter, use the
command reference master index or search online.

• Finding Feature Information, page 1

• Token Ring LANE on ATM, page 2

• Network Support, page 3

• Restrictions, page 4

• Prerequisites, page 5

• Token Ring LANE Configuration Task List, page 6

• Token Ring LANE Configuration Example, page 28

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats
and feature information, see Bug Search Tool and the release notes for your platform and software release.
To find information about the features documented in this module, and to see a list of the releases in which
each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Cisco IOS Switching Services

Americas Headquarters:
Cisco Systems, Inc., 170 West Tasman Drive, San Jose, CA 95134-1706 USA

Token Ring LANE on ATM

Token Ring LANE on ATM

LANE bridges LAN traffic across an ATM network. The Catalyst 5000 Series Token Ring LANE feature
emulates an IEEE 802.5 Token Ring LAN using ATM technology. LANE is transparent to upperlayer
protocols and applications. No changes are required to existing upperlayer protocols and applications. With
Token Ring LANE, Token Ring packets are encapsulated in the appropriate ATM cells and sent across the
ATM network. When the packets reach the other side of the ATM network, they are deencapsulated.

• Benefits, page 2

• LANE Token Ring Components, page 2

Benefits

ATM is a cell-switching and multiplexing technology that combines the benefits of circuit switching
(constant transmission delay and guaranteed capacity) with those of packet switching (flexibility and
efficiency for intermittent traffic). Like X.25 and Frame Relay, ATM defines the interface between the user
equipment (such as workstations and routers) and the network (referred to as the User-Network Interface
[UNI]).

Benefits

Token Ring LANE allows Token Ring LAN users to take advantage of the benefits of ATM without
modifying end-station hardware or software. ATM uses connection-oriented service with point-to-point
signalling or multicast signalling between source and destination devices. However, Token Ring LANs use
connectionless service. Messages are broadcast to all devices on the network. With Token Ring LANE,
routers and switches emulate the connectionless service of a Token Ring LAN for the end stations.

By using Token Ring LANE, you can scale your networks to larger sizes while preserving your investment
in LAN technology.

Note

The Catalyst 5000 series Cisco IOS Token Ring LANE software does not support Ethernet LANE or RFC
1483 permanent virtual connections (PVCs).

LANE Token Ring Components

LANE defines emulated LANs (ELANs). An ELAN consists of the following components:

• LANE client (LEC)--A 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 switch or a Catalyst ATM module can include LECs
for multiple ELANs; there is one LEC for each ELAN of which it is a member.

If a switch has LECs for multiple ELANs, the switch can route traffic between ELANs.

• LANE server (LES)--The LES is the control center for an ELAN. It provides joining, address
resolution, and address registration services to the LECs in that ELAN. LECs can register destination
unicast and multicast MAC address with the LES. The LES also handles LANE Address Resolution
Protocol (LE_ARP) requests and responses and maintains a list of route descriptors that is used to
support source-route bridging (SRB) over ELANs. The route descriptors are used to determine the
ATM address of the next hop in the frame’s routing information field (RIF).

There is one LES per ELAN.

2

LANE Token Ring Components

• LANE broadcast and unknown server (BUS)--The BUS floods unknown destination traffic and

One combined LES and BUS is required for each ELAN.

• LANE Configuration Server (LECS)--The LECS contains the database that determines which ELAN a

One LECS is required for each ATM LANE switch cloud.
The LECS database can have the following types of entries:

• ◦ ELAN name, ATM address of LES pairs

Network Support

forwards multicast and broadcast traffic to LECs within an ELAN.

device belongs to (each LECS can have a different database). Each LEC contacts the LECS once to
determine which ELAN it should join. The LECS returns the ATM address of the LES for that ELAN.

◦ ELAN name and the ring number of the ELAN (local-seg-id)
◦ LEC MAC address, ELAN name pairs
◦ LEC ATM template, ELAN name pairs
◦ Default ELAN name

Note

Note

An ELAN name must be unique on an interface. If two interfaces participate in LANE, the second interface
may be in a different switch cloud.

The server assigns individual LECs to particular ELANs by directing them to the LES for the ELAN. The
LECS maintains a database of LEC and server ATM or MAC addresses and their ELANs. A LECS can
serve multiple ELANs.

• Fast Simple Server Redundancy Protocol (FSSRP)--Token Ring LANE relies on three servers: LECS,

LES, and BUS. If any one of these servers fails, the ELAN cannot fully function.

Cisco has developed a fault tolerant mechanism known as Simple Server Redundancy Protocol (SSRP) that
eliminates these single points of failure. Although there is only one LES per ELAN, SSRP allows you to
configure redundant servers. You can configure servers to act as backup servers that become active if a
master server fails. The priority levels for the servers determine which servers have precedence.

FSSRP is an enhancement to the SSRP. With FSSRP, LECs no longer need to go down whenever there is a
change in the master LES. This uninterrupted service is achieved by connecting the LECs simultaneously
to more than one LES/BUS (up to four) so that if the master LES goes down, the backup LESs are
immediately available. With the basic SSRP, the LEC must go down and completely recycle before coming
back up. This operation is accomplished by keeping the control connections open to all of the active LESs
and BUSs in the ELAN. Although this method uses more virtual circuits (VCs), the main benefits are the
transparency and speed in the switchover.

ELAN components coexist on one or more Cisco routers or Catalyst switches that contain an ATM module.
On Cisco routers or Catalyst switches the LES and the BUS are combined into a single entity.

Network Support

The Token Ring LANE on the Catalyst 5000 series ATM module feature supports the following
networking features:

• LAN switching between ELANs and between a Token Ring ELAN and a legacy LAN

3

Restrictions

The Cisco implementation of LANE over IEEE 802.5 uses existing terminology and configuration options
for Token Rings and provides for the IEEE 802.5 transport of Token Ring frames across an ATM switching
fabric.

Restrictions

Before you implement Token Ring LANE, be aware of the following restrictions:

LANE Token Ring Components

• Two-port and multiport SRB between ELANs and between ELANs and a Token Ring LAN

• SRB, source-route transparent bridging (SRT), and source-route switching

Caution

Note

While VLAN Trunking Protocol (VTP) Version 2 must be enabled on a Catalyst 5000 for Token Ring to
function, do not use VTP to distribute VLAN configuration information between the switches. Configure
the switches to operate in VTP transparent mode and manually configure the VLANs on each switch.

• If you plan to run both Ethernet and Token Ring LANE, the Ethernet LANE software and the Token
Ring LANE software must be run on separate ATM modules.

• All ATM switches have identical lists of the global LECS addresses with the identical priorities.

• Ensure that the spanning-tree port cost and priority for the ATM port are configured so that the ATM
port is the preferred path (the lowest port cost with the highest priority).

• Only one LEC can be defined for each subinterface. Up to 256 subinterfaces per ATM module can be
configured.

• Do not create more than one LEC for each Token Ring Bridge Relay Function (TrBRF) in each ATM
module.

While you can have only one LEC for each TrBRF in each module, you can have more than one module
installed. These additional modules allow you to have more than one LEC per TrBRF, which means the
module can participate in more than one ELAN. The ELANs, however, cannot be parallel or the Spanning­Tree Protocol will block one of the connections.

Configuring more than one LEC for a TrBRF on a single ATM module will adversely affect frame
forwarding.

• Do not configure parallel ELANs within a TrBRF (parallel ELANs are those ELANs that form a loop
between switches).

• Do not create more than one LEC for each Token Ring Concentrator Relay Function (TrCRF) per
ATM module.

• Ensure that all-routes explorer (ARE) reduction is enabled (using the set tokenring reduction enable
command) on the Token Ring module.

• The number of LESs that can be defined per ELAN is unlimited; however, only one LES per ELAN
can be active at a time.

• When a LECS switchover occurs, no previously joined clients are affected.

• In a 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 takes priority.

• Using FSSRP, you can configure redundant LESs or BUSs and LECSs to reduce the possibility of a
server failure resulting in loss of communication on the LANE network. With redundant LES/BUSs

4

LANE Token Ring Components

Prerequisites

and LECSs, LANE components can switch automatically to the backup LES/BUS or LECS if the
primary server fails. For specific information on how to configure FSSRP, refer to the Configuring

Fast SSRP for Redundant LANE Services, page 24 section.

Note

Note

FSSRP works only with LECS and LES/BUS combinations on Cisco devices. Third-party LANE
components interoperate with the LECS and LES/BUS functions of Cisco devices but cannot take
advantage of the redundancy features. Additionally, FSSRP-unaware LECs on Cisco equipment cannot
take advantage of FSSRP LES/BUS redundancy.

• When a higher-priority LES comes online, it bumps the current LES off the same ELAN. For a short

time after power on, some clients might change from one LES to another, depending upon the order of
the LESs coming up.

• If no LES/BUS pair is up or connected to the master LECS, and more than one LES/BUS 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 LECS database regarding LES addresses take effect almost
immediately.

• If no LECS is operational or reachable, the "well-known" LECS address defined by the ATM Forum is

used.

• The LECS to be used can be overridden on any subinterface by entering the following command:

lane config-atm address

atm-address template

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

• In an underlying ATM network failure, there can be multiple master LECS and multiple active LESs

Prerequisites

Token Ring LANE requires that the Catalyst 5000 series switch contain one of the following ATM
modules running ATM software Release 4.9b or later:

• ATM Dual PHY OC-12 (WS-X5161 and WS-X5162)

• ATM Dual PHY OC-3 (WS-X5167 and WS-X5168)

These ATM modules provide an ATM network interface for the Catalyst 5000 series switch. Network
interfaces reside on modular interface processors, which provide a direct connection between the high­speed synergy backplane and the external networks. The maximum number of ATM modules that the
switch supports depends on the bandwidth configured.

The Catalyst 5000 series Token Ring LANE software also requires the Catalyst 5000 series supervisor
engine software Release 4.3(1a) or later and one of the following switches:

• Cisco LightStream 1010 with Cisco IOS Release 12.0(1)W5 or later (recommended)

or BUSs for the same ELAN, resulting in a partitioned network. Clients continue to operate normally,
but transmission between partitions of the network is not possible. The system recovers when the
network break is repaired.

5

Token Ring LANE Configuration Task List

• Any ATM switch with UNI 3.0/3.1 and Interim Local Management Interface (ILMI) support for
communicating the LECS address

Opening a Session from the Switch to the ATM Module

Note

If you plan to run both Ethernet and Token Ring LANE, the Ethernet LANE software and the Token Ring
LANE software must be run on separate ATM modules.

Token Ring LANE Configuration Task List

Note

Note

There can be multiple LECSs in an ATM cloud.

Before configuring Token Ring LANE, you must first open a session with the ATM module in the Catalyst
5000 series switch by entering the session line configuration command from the supervisor Console>
prompt. After opening the session, you see the ATM> prompt. You only have direct access 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. After configuring the ATM module, you are ready to
implement LANE.

• Opening a Session from the Switch to the ATM Module, page 6

• Creating a LANE Plan and Worksheet, page 7

• Configuring the ATM Module from the Terminal, page 8

• Configuring the ATM Module from NVRAM, page 9

• Configuring the Prefix on the LightStream 1010 Switch, page 9

• Setting Up the Signalling PVC, page 10

• Displaying LANE Default Addresses, page 11

• Entering the LECS ATM Address on the LightStream 1010 Switch, page 11

• Configuring the LECS Database, page 12

• Binding the LECS to the ATM Interface, page 17

• Setting Up a LES BUS and a LEC, page 18

• Configuring Redundant LANE Services, page 22

• Verifying the LANE Setup, page 27

• Monitoring and Maintaining LANE Components, page 27

Opening a Session from the Switch to the ATM Module

Use the session mod_num line configuration command to open a session to the ATM module from the
Catalyst 5000 family switch in which the module is installed.

This example shows how to create a session to an ATM module installed in slot 5 of the Catalyst 5000
switch:

Console> (enable) session 5
Trying ATM-5...

6

Creating a LANE Plan and Worksheet

Connected to ATM-5.
Escape character is '^]'.

ATM>

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.

Token Ring LANE Configuration Task List

Note

Note

The ATM module uses a subset of Cisco IOS software. Generally, Cisco IOS software works the same on
the ATM module as it does on routers.

To configure the ATM module, you must use the ATM configuration mode in the Cisco IOS software. To
enter global configuration mode, enter the configure EXEC command 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]?

If you specify terminal, the run-time configuration is used. You can then save the run-time configuration
into the NVRAM. If you specify memory, the run-time configuration is updated from the NVRAM. If you
specify network, the run-time configuration is updated from a file in a server on the network.

You cannot configure from the network.

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 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.

Creating a LANE Plan and Worksheet

Before you begin to configure Token Ring LANE, you must decide whether you want to set up one or
multiple ELANs. If you set up multiple ELANs, you must also decide where the servers and LECs will be
located, and whether to restrict the clients that can belong to each ELAN. Bridged ELANs are configured
just like any other LAN, in terms of commands and outputs. Once you have made those decisions, you can
configure Token Ring LANE.

Before implementing Token Ring LANE, it might help you to begin by drawing up a plan and a worksheet
for your own LANE scenario, showing the following information and leaving space to note the ATM
address of each LANE component on each subinterface for each participating switch:

• Catalyst 5000 series switch interface where the LECS will be located.

• Catalyst 5000 series switch interface and subinterface where the LES/BUS for each ELAN will be

located. For fault-tolerant operation, multiple servers can be on each ELAN.

• Catalyst 5000 series switch ATM modules, subinterfaces, and VLANs where the LECs for each ELAN

will be located.

• Name of the default ELAN (optional). The default Token Ring ELAN is the same as the default

TrCRF (1003). You can use the default Token Ring ELAN (trcrf-default) or configure a new one.

7

Default LANE Configuration

• Names of the ELANs that will have unrestricted membership.

• Names of the ELANs that will have restricted membership.

• Local segment ID for the ELAN. The local segment ID must be identical to the ring number of the
TrCRF.

Configuring the ATM Module from the Terminal

Note

The last three items in the list above are important because they determine how you set up each ELAN in
the LECS database.

• Default LANE Configuration, page 8

Default LANE Configuration

The table below shows the default LANE configuration.

Table 1 Default LANE Configuration

Feature Default Value

LANE components No LECS database is configured.

PVCs ILMI and signalling PVCs are set up.
Preferred PHY (Dual PHY modules only) PHY A
Output throttling Disabled
ILMI keepalives Disabled

No LES/BUS is configured.
No LECs are configured.

UNI version Autonegotiate (reverts to UNI 3.0 if autonegotiation

fails)

VTP Disabled

Configuring the ATM Module from the Terminal

To configure the ATM module from the terminal, use the following commands beginning in privileged
EXEC mode:

SUMMARY STEPS

1.

ATM# configure terminal

2.

ATM(config)# interface atm>elanname

3.

ATM(config-if)# lane client tokenring>elanname

4.

ATM(config-if)# Ctrl-Z

5.

ATM(config)# write memory

8

Configuring the ATM Module from NVRAM

DETAILED STEPS

Command or Action Purpose

Default LANE Configuration

Step 1

Step 2

Step 3

Step 4

Step 5

ATM# configure terminal
ATM(config)# interface atm>elanname
ATM(config-if)# lane client tokenring>elanname

ATM(config-if)# Ctrl-Z
ATM(config)# write memory

In the following example, the ATM module is configured from the terminal. The interface atm 0 interface
configuration command designates that ATM interface 0 is to be configured. The lane client tokenring
command links TrCRF 10 to the ELAN named trcrf-10. 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-subif)# lane client tokenring 10 trcrf-10
ATM (config-subif)# 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.

Selects the terminal option and enters global configuration mode.
Selects an ATM ELAN subinterface.
Identifies the ELAN attached to this subinterface as a Token Ring

ELAN.
Exits global configuration mode.
Saves the configuration file modifications to NVRAM.

Configuring the ATM Module from NVRAM

To configure the ATM module from NVRAM, reexecute the configuration commands in privileged EXEC
mode:

Command

Purpose

Configures the ATM module from NVRAM.

ATM(config)# configure memory

Configuring the Prefix on the LightStream 1010 Switch

Before you configure LANE components on a Catalyst 5000 series switch ATM module, you must
configure the Cisco LightStream 1010 switch with the ATM address prefix to be used by all LANE
components in the switch cloud.

9

Default LANE Configuration

Setting Up the Signalling PVC

Note

Note

DETAILED STEPS

Command or Action Purpose

Step 1

Switch(config)# atm address {atm_address | prefix... }

On the Cisco LightStream 1010 switch, the ATM address prefix is called the node ID. Prefixes must be 26
digits long. If you provide fewer than 26 digits, zeros are added to the right of the specified value to fill it to
26 digits. LANE prefixes must start with 39 or 47.

If you do not save the configured value permanently, it will be lost when the switch is reset or powered off.

To display the current prefix on the Cisco LightStream 1010 switch, use the show network EXEC
command.

To set the ATM address prefix, use the following commands on the Cisco LightStream 1010 switch
beginning in global configuration mode:

SUMMARY STEPS

1.

Switch(config)# atm address {atm_address | prefix... }

2.

Switch(config)# exit

3.

Switch# copy running-config startup-config

Sets the local node ID (prefix of the ATM address).

Step 2

Step 3

Switch(config)# exit
Switch# copy running-config startup-config

Setting Up the Signalling PVC

You must set up the signalling PVC and the PVC that will communicate with the ILMI on the major ATM
interface of any Catalyst 5000 series switch that participates in LANE. Complete this task only once for a
major interface. You need not repeat this task on the same interface even though you might configure LESs
and clients on several of its subinterfaces.

To set up these PVCs, use the following commands beginning in global configuration mode:

SUMMARY STEPS

1.

ATM(config)# interface atmslot/port

2.

ATM(config)# atm pvcvcd vpi vci qsaal

3.

ATM(config)# atm pvcvcd vpi vciilmi

DETAILED STEPS

Step 1

Command or Action

ATM(config)# interface atmslot/
port

Purpose

Specifies the major ATM interface and enters interface configuration mode.

Exits global configuration mode.
Saves the configuration values permanently.

10