This chapter provides an overview of LAN Emulation (LANE), describes the key LANE components in an emulated LAN (ATM-VLAN), and shows you how to use the AtmDirector ATM-VLAN topology view to display topology information for a fabric or ATM-VLAN. This chapter includes instructions for showing the roles of devices in a fabric and for displaying summary information for an ATM-VLAN.
LANE enables existing applications to access an ATM network as if they were operating over traditional LANs, such as Ethernet or Token Ring. LANE allows LAN users to benefit from ATM without modifying end-system hardware or software. End systems on LANs can connect to other end systems on LANs, as well as to ATM-attached servers, routers, and switches.
LANE reconciles the differences between ATM and LAN protocols by masking the connection setup and handshaking functions required by the ATM switch. In addition, it maps the MAC address-based networking protocols into ATM virtual channels. Thus, LANE essentially bridges LAN traffic across ATM.
LANE has specific hardware requirements. For details, refer to your switch or router documentation.
Each ATM-VLAN in an ATM cloud comprises a set of the following LANE components:
- A LANE client, sometimes called LEC, is typically an ATM adapter, router, or LAN switch with ATM interface, that provides a standard LAN service to any higher-layer entity, such as IP and IPX protocols. The client performs data forwarding, address resolution, and other control functions for a single endpoint in a single ATM-VLAN.
- Each ATM adapter, router, or LAN switch can support multiple instances of a client, with a separate client for each connected ATM-VLAN. The client registers its MAC and ATM address with the LE server.
- The LAN Emulation (LE) server, sometimes called LES, provides joining, address resolution, and address registration facilities for the clients in its ATM-VLAN. It handles LAN Emulation Address Resolution Protocol (LE_ARP) requests and responses by resolving Ethernet or Token Ring MAC addresses to ATM addresses.
- The LE server is identified by a unique ATM address. Clients can communicate directly with one another only when they are connected to the same LE server. However, multiple LE servers can exist on the same physical ATM network where each server supports a different ATM-VLAN.
- The broadcast server, sometimes called broadcast and unknown server (BUS), is a multicast server that receives all broadcast, multicast, and unknown unicast packets and transmits them to every client within an ATM-VLAN. A client is associated with a single broadcast server for each ATM-VLAN.
- Each broadcast server is identified by a unique ATM address, which the server associates with a broadcast MAC address. One combined LE server and broadcast server is required per ATM-VLAN.
- The LANE configuration server, sometimes called LECS, assigns individual clients to particular ATM-VLANs by directing them to the LE server that corresponds to the ATM-VLAN. The configuration server maintains configuration information about the ATM-VLANs in a network and supplies the address of the LE server to a client when it is initialized.
- In an ATM fabric there must be just one configuration server that serves all ATM-VLANs in the fabric. Network administrators also use the configuration server to control which physical LANs are combined to form VLANs.
Note Because the LE server, broadcast server, and configuration server are potential points of failure, we have developed a fault tolerance mechanism. This proprietary mechanism, known as Simple Server Redundancy Protocol, eliminates these single points of failure by providing for both a primary and backup instance of the LE server, broadcast server, and configuration server.
The LANE components communicate with each other using virtual channel connections (VCCs). These connections are of the following types:
- Configure direct
- Control direct
- Control distribute
- Multicast send
- Multicast forward
- Data direct
These VCCs are utilized for connection setup and data transfer in three stages:
- Initialization and configuration
- Joining and registration
- Data transfer
For detailed descriptions of VCCs and LANE call setup, refer to your CiscoView and hardware documentation.
AtmDirector, in conjunction with VlanDirector, provides discovery of all the ATM-VLANs in a network, their association with the VLANs, and the client server topology of each of the discovered ATM-VLANs.
Discovery specifically provides the following:
- Discovery of all ATM-VLANs in the network, including identification of the clients, LE servers, and broadcast servers in each ATM-VLAN
- Association of ATM-VLANs with VLANs
- Identification of configuration servers (master and backup)
From the fabric topology map you can display a list of ATM-VLANs that pass through a device, together with the function of the device in each ATM-VLAN. You might use this information when, for example, you want to take a device off line and need to know what will be affected.
To display a catalog of information about all the devices in a fabric, follow these steps:
Step 1 Double-click on a fabric name in the AtmDirector main window to display the fabric topology.
Step 2 Select ATM-VLAN>ATM-VLAN Catalog.
The ATM-VLAN Catalog window opens (Figure 4-1).
Figure 4-1: ATM-VLAN Catalog Window
Step 3 Click the arrow button to the right of the Host Name field and select a host device from the popup list.
The information in the ATM-VLAN Catalog window is described in Table 4-1.
Step 4 Click OK when you have read the device catalog.
Table 4-1: ATM-VLAN Catalog Field Descriptions
| Field
| Description
|
|---|
| Fabric Name
| Fabric for which this window shows information.
|
| Host Name
| Name of the currently selected device. You can display the catalog for another device by selecting from this popup field. This list contains only the hosts on which LANE components are running.
|
| ATM-VLANs passing through the device
|
|
| ATM-VLAN Name
| Names of the ATM-VLANs in which the selected device participates.
|
| LE Server
| Whether this device functions as the LE server (master or backup) for this ATM-VLAN.
|
| Bcast Server
| Whether this device functions as the broadcast server (master or backup) for this ATM-VLAN.
|
| Config Server
| Whether this device functions as the configuration server (master or backup) for this ATM-VLAN.
|
| Clients
| Whether this device has clients running on it.
|
From the AtmDirector main window, you can launch a topology map for any ATM-VLAN in a fabric. The topology display includes the devices and ATM-VLAN components, together with their status, that participate in the ATM-VLAN.
To display the topology map for an ATM-VLAN:
- Double-click on an ATM-VLAN name from the AtmDirector main window.
The topology service is launched for the selected ATM-VLAN, and the topology window is displayed (Figure 2-4).
The ATM-VLAN topology map displays the following elements:
- Devices that participate in this ATM-VLAN--Catalyst 5000 series switches that have LANE components running on them, LightStream 1010 series switches that participate in traffic switching, Catalyst 7000 series routers, and all edge devices connected to the LightStream 1010 switches.
- LANE components running on each device--Devices are annotated with icons for client, LE server, broadcast server, and configuration server to show which components reside on the device. A key to the component icons is found across the bottom of the window.
- Operational status of components, devices, and links--For a description of status color coding, see "Monitoring ATM-VLANs and LANE Components" in Chapter 6, "Monitoring the Status of Your ATM Network."
The ATM-VLAN Summary window provides summary information about the currently displayed ATM-VLAN and its LANE components.
To display summary information for an ATM-VLAN, follow these steps:
Step 1 From the AtmDirector main window, double-click on the name of an ATM-VLAN to display the ATM-VLAN topology window (Figure 2-4).
Step 2 Select ATM-VLAN>Summary.
The ATM-VLAN Summary window opens (Figure 4-2). The information in this window is described in Table 4-2.
Step 3 Click OK when you have read the summary information.
Figure 4-2: ATM-VLAN Summary Window
Table 4-2: ATM-VLAN Summary Field Descriptions
| Field
| Description
|
|---|
| ATM-VLAN Name
| Administrative name assigned to the ATM-VLAN
|
| Fabric Name
| Name of fabric to which this ATM-VLAN belongs
|
| Type
| Ethernet/IEEE 802.3, IEEE 802.5, or Unspecified
|
| MTU
| Maximum transfer unit, or the maximum negotiable packet size for this ATM-VLAN
|
| Number of Active Clients
| Currently active clients in this ATM-VLAN
|
| Short Description
| Short description of entered in the VlanDirector application when this ATM-VLAN was created
|
| Long Description
| Long description of entered in the VlanDirector application when this ATM-VLAN was created
|
| LE Server
|
|
| Host name
| Name of the master LE server for this ATM-VLAN
|
| ATM Address
| ATM address of the master LE server
|
| Broadcast Server
|
|
| Host name
| Name of the master broadcast server for this ATM-VLAN
|
| ATM Address
| ATM address of the master broadcast server
|
