LAN Emulation (LANE) provides an emulated IEEE 802.3 Ethernet or IEEE 802.5 Token Ring network over an ATM network. LANE can be used to transport traditional LANs over an ATM backbone or an ATM WAN cloud.
LANE uses the concept of Emulated LANs (ELANs) to segment traffic into logical networks within the ATM domain.
LANE consists of several logical components , each configured on a router, switch, or ATM switch:
LAN Emulation Configuration Server (LECS) This is the central administrative control point for all ELANs in a domain. The LECS keeps a database of ELANs and the ATM addresses of the LANE servers that control each ELAN. (There is only one LECS per administrative domain.)
LAN Emulation Server (LES) This is the central control point for all LANE clients in an ELAN. The LES provides MAC-to-NSAP address translation for each LANE client. (There is only one LES per ELAN.)
Broadcast and Unknown Server (BUS) The BUS handles all broadcasts sent from a LANE host. The LANE client must forward any broadcast or multicast from an end user to the BUS. The BUS can then replicate the broadcast to all other LANE clients in the domain.
LAN Emulation Client (LEC) The LEC provides the basic ELAN function at the edge of the ATM network. The LEC emulates an interface to a traditional LAN and provides data forwarding, address resolution, and MAC address registration with the other LANE components. A LEC is needed at any location where network layer addresses are used.
Multiple LANE components can be configured in the network for redundancy. Simple Server Redundancy Protocol (SSRP) handles the communication between the active and standby components so that no single point of failure can exist within the components.
NOTE
ATM addresses use the Network Service Access Point (NSAP) format, a 20-byte value. Typically, NSAP addresses are written as groups of four hex digits separated by dots. The leftmost and rightmost two hex digits are usually grouped by themselves . The address is composed of the following parts :
Prefix A 13-byte field that uniquely identifies every ATM switch in the network. Cisco ATM switches use a predefined 7-byte value of 47.0091.8100.0000, followed by the switch's 6-byte MAC address.
End-System Identifier (ESI) A 6-byte field that uniquely identifies every device attached to an ATM switch. Typically, this is the device's 6-byte MAC address (an ATM router interface, for example).
Selector A 1-byte field that identifies a process running on an ATM device. Cisco devices usually use the ATM subinterface number as the selector value.
The prefix value always comes from the ATM switch. The ESI value is determined from the ATM interface MAC address as follows : LEC (MAC address), LES (MAC address + 1), BUS (MAC address + 2), and LECS (MAC address + 3). The selector is the ATM subinterface number, except for the LECS, which must always be configured on a major ATM interface (selector 00).
Define the control PVCs.
Select the major ATM interface:
(global) interface atm slot /0
Define the ATM signaling PVC:
(interface) atm pvc vcd 5 qsaal
The signaling PVC uses QSAAL and usually operates over VPI/VCI 0 5. The vcd is the Virtual Circuit Descriptor, an arbitrary number (1 to 2047) used to uniquely identify the PVC.
Define the ILMI PVC:
(interface) atm pvc vcd 16 ilmi
ILMI communication between the router and the ATM switch is usually configured over VPI/VCI 0 16. The vcd field can be arbitrarily set to identify the PVC.
Display the default LANE addresses on the ATM interface:
(exec) show lane default-atm-addresses
The default NSAP addresses for the LANE components are shown. If the router has received the prefix portion of the address from an ATM switch, the entire NSAP address is shown. Otherwise, only the ESI or MAC address portion is displayed. These NSAP addresses will be used in further LANE configuration steps. Here is an example of the output from a router with two ATM interfaces:
(router) show lane default-atm-addresses interface ATM5/0: LANE Client: 47.00918100000000E01E35A301.00E0FE1400A0.** LANE Server: 47.00918100000000E01E35A301.00E0FE1400A1.** LANE Bus: 47.00918100000000E01E35A301.00E0FE1400A2.** LANE Config Server: 47.00918100000000E01E35A301.00E0FE1400A3.00 interface ATM6/0: LANE Client: 47.00918100000000E01E35A901.00E0FE1400C0.** LANE Server: 47.00918100000000E01E35A901.00E0FE1400C1.** LANE Bus: 47.00918100000000E01E35A901.00E0FE1400C2.** LANE Config Server: 47.00918100000000E01E35A901.00E0FE1400C3.00
Note: ** is the subinterface number byte in hex.
Define the LECS.
Configure the LECS database.
Name the database:
(global) lane database database-name
The LECS database is named database-name (a 1- to 32-character string).
Define an ELAN and its LES:
(lane-database) name elan-name server-atm-address atm-address [ restricted ] [ index index ]
The ELAN named elan-name (a 1- to 32-character string) is bound to the LES at atm-address (a 20-byte NSAP address). The NSAP address can be obtained from the show lane default-atm-addresses command on the router that will have the LES component. The restricted keyword can be used to restrict ELAN membership to only those clients explicitly listed in the database in Step 4.
NOTE
To use SSRP for redundancy, multiple LES components can be defined for a given ELAN. The index keyword must be used to assign a priority to each LES (0 is the highest priority).
(Unrestricted ELAN membership) Define a default ELAN name:
(lane-database) default-name elan-name
For an unrestricted membership ELAN, any client attempting to register itself with the LECS is joined to the ELAN named elan-name (a 1- to 32-character string).
(Restricted ELAN membership) Define specific LECs and their ELAN:
(lane-database) client-atm-address atm-address name elan-name
For a restricted membership ELAN, any client attempting to register itself with the LECS must be specifically identified by its atm-address (a 20-byte value, 40 hex digits; * can match any digit and can match any number of digits). The matching client is joined to the ELAN named elan-name (a 1- to 32-character string).
Enable the LECS.
Select an ATM major interface:
(global) interface atm slot/
Use a specific LECS database:
(interface) lane config database database-name
Determine the LECS ATM address.
NOTE
To use redundant LECS components, each LECS ATM address must be configured in the ATM switch. As each LANE client initializes, it contacts the ATM switch through ILMI and is provided a list of all the LECS addresses. If multiple ATM switches are used within the ELAN domain, all ATM switches must have an identical list of LECS addresses in the same order. Also, each redundant LECS must have an identical database.
You can use three different ATM addresses for the LECS.
To use the automatic or predetermined address, use the following command:
(interface) lane config auto-config-atm-address
The LECS address is created from the value shown by the show lane default-atm-addresses command.
To use the well-known LECS address, use the following command:
(interface) lane config fixed-config-atm-address
The LECS address will be the well-known NSAP 47.007900000000000000000000.00A03E000001.00.
To use a specific ATM address, use the following command:
(interface) lane config config-atm-address nsap-address
The LECS receives the nsap-address (a 20-byte value, or 40 hex digits). The address can be given as a template, using * to match any single hex digit or to match any number of leading, middle, or trailing hex digits.
Define a LES/BUS pair.
Select an ATM subinterface:
(global) interface atm slot / 0. subinterface
An arbitrary subinterface number can be used for the LES/BUS components. However, only one LES/BUS can be configured on a subinterface, serving only a single ELAN.
Enable the LES/BUS:
(interface) lane server-bus { ethernet tokenring } elan-name
A LES and BUS are created for the ELAN named elan-name (a 1- to 32-character string). The emulated LAN can act as an ethernet or tokenring network.
Define a LEC.
Select an ATM subinterface:
(global) interface atm slot / 0. subinterface
An arbitrary subinterface number can be used for the LEC component. A LEC can be configured on the same subinterface as the LES/BUS pair. However, only one LEC can be created on a single subinterface, serving a single ELAN.
Enable the LEC:
(interface) lane client { ethernet tokenring } [ elan-name ]
The LEC is configured to emulate either an Ethernet or Token Ring network. When the LEC joins the ELAN, the LECS already has the ELAN name for the client in its database. The ELAN name, elan-name, can be given so that the LEC will present the ELAN name to the LECS for additional matching.
Define any network layer addresses.
The LEC's subinterface can be configured with any network layer addresses, network numbers , bridging information, and so forth, so that the router can transport traffic between the ELAN and other physical interfaces.
The following commands can be used to display the status of the LANE components:
vLECS (exec) show lane client
LECS database (exec) show lane database
LES (exec) show lane server
BUS (exec) show lane bus
LEC (exec) show lane client
If you are having trouble passing traffic over a LEC, use the show lane client command to see if the LEC has been able to join the ELAN. The output for a successfully joined LEC is as follows:
LE Client ATM5/0.1 ELAN name: Engineering Admin: up State: operational Client ID: 12 LEC up for 4 days 13 hours 32 minutes 17 seconds ELAN ID: 0 Join Attempt: 3 Known LE Servers: 1 HW Address: 00e0.fe14.00a0 Type: ethernet Max Frame Size: 1516 ATM Address: 47.00918100000000E01E35A301.00E0FE1400A0.01 VCD rxFrames txFrames Type ATM Address 0 0 0 configure 47.00918100000000E01E35A801.00E01E35A805.00 4 1 21674 direct 47.00918100000000E01E35A801.00E01E35A803.00 5 392627 0 distribute 47.00918100000000E01E35A801.00E01E35A803.00 6 0 68849 send 47.00918100000000E01E35A801.00E01E35A804.00 7 833455 0 forward 47.00918100000000E01E35A801.00E01E35A804.00 9 35774 1079075 data 47.00918100000000E01E35A801.00E01E2206A0.01 1486 2 1 data 47.00918100000000E01E35A301.00E01E35A302.00 1483 0 1 data 47.00918100000000E01E35AC01.00E01E35AC02.00 1481 0 4 data 47.00918100000000E01E35AC01.006070D78820.01 11 87227 5010878 data 47.00918100000000E01E35A301.00E0FE13F0A0.01 1468 5 0 data 47.00918100000000E01E35A801.00503ED30C10.01 1482 0 3 data 47.00918100000000E01E35A301.00E0FE1408A0.01 8 26655 1465697 data 47.00918100000000E01E35A801.00E0FE1468A0.01
A router is configured for LANE in a hospital environment. As soon as the signaling and ILMI PVCs are configured, the router can complete all the parts of the default ATM addresses. The default addresses on the local router are shown in the example, and the default addresses of other routers are also collected. A LECS database for the hospital is configured as hospital-db. An ELAN named radiology is configured with restricted membership. Two LES addresses are listed for redundancy: the local router's LES as priority 0, and another router's LES as priority 1. For simplicity, only one LEC is listed and can join the radiology ELANthe LEC on the local router.
A second ELAN named surgery is also configured with unrestricted membership. By default, a LEC is joined to the surgery ELAN.
The LECS is configured on interface atm 8/0, a LES/BUS for radiology on interface atm 8/0.1, and a LES/BUS for surgery on interface atm 8/0.2. Finally, a LEC in the radiology ELAN is configured on interface atm 8/0.3. Notice that the ATM addresses listed in the database have the correct LANE component value in the last ESI digit (0 = LEC, 1 = LES, 2 = BUS, 3 = LECS). The selector value also has the appropriate subinterface number used in the interface configuration. Figure 2-7 shows a network diagram.
interface atm 8/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi no shutdown exit show lane default-atm-addresses LANE Client: 47.00918100000000E01E35A901.00E0FE1400C0.** LANE Server: 47.00918100000000E01E35A901.00E0FE1400C1.** LANE Bus: 47.00918100000000E01E35A901.00E0FE1400C2.** LANE Config Server: 47.00918100000000E01E35A901.00E0FE1400C3.00 (This command is also run on other LES and LEC routers so that the LANE component addresses can be added to the configuration.) config terminal lane database hospital-db name radiology server-atm-address 47.00918100000000E01E35A901.00E0FE1400C2.01 restricted index 0 name radiology server-atm-address 47.00918100000000E01E35A901.00E0FE121042.01 restricted index 1 client-atm-address 47.00918100000000E01E35A901.00E0FE1400C0.03 name radiology name surgery server-atm-address 47.00918100000000E01E35A901.00E0FE1400C2.02 index 0 name surgery server-atm-address 47.00918100000000E01E35A901.00E0FE121042.02 index 0 default-name surgery interface atm 8/0 description LECS for hospital ATM network lane config database hospital-db lane config auto-config-atm-address interface atm 8/0.1 description LES/BUS for radiology ELAN lane server-bus ethernet radiology interface atm 8/0.2 description LES/BUS for surgery ELAN lane server-bus ethernet surgery interface atm 8/0.3 description LEC for radiology ELAN lane client ethernet radiology ip address 192.168.34.1 255.255. 255.0