Table of Contents

ALPS Overview
ALPS Configuration Task List
Configuring the Remote Routers

Specifying the ALPS Local Peer IP Address
Specifying the ALPS Remote Peer IP Address
Specifying the ALPS Circuit
Specifying Each ASCU

Configuring the Data Center Router

Specifying the ALPS Host Local Peer Address
Specifying AX.25
Specifying EMTOX

Customizing the Service Messages
Customizing the Alarm Notifications
Updating a Circuit
Verifying ALPS
Monitoring and Maintaining ALPS
ALPS Configuration Examples

ALPS with MATIP Configuration for ALC and UTS Example
ALPS Configuration for ALC and AX.25 Example
ALPS Configuration for UTS and EMTOX Example

Configuring the Airline Product Set

This chapter describes how to configure the Airline Product Set (ALPS). For a complete description of the ALPS commands in this chapter, refer to the "Airline Product Set Configuration Commands" chapter in the Cisco IOS Bridging and IBM Networking Command Reference, Volume I. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.

• ALPS Overview

• ALPS Configuration Task List

• Monitoring and Maintaining ALPS

• ALPS Configuration Examples

ALPS Overview

ALPS is a tunneling mechanism that transports airline protocol data across a Cisco router-based TCP/IP network to a mainframe. This feature provides connectivity between agent set control units (ASCUs) and a mainframe host that runs the airline reservation system.

The ALPS feature was released in three phases. The first two phases of ALPS enabled the network migration to TCP/IP without requiring any changes in the hardware or software of the endstations (ASCUs and mainframes). ALPS phase I and II utilized a new protocol, ALPS Tunneling Protocol (ATP), to tunnel airline protocol traffic (P1024B Airline Control (ALC) or P1024C Universal Terminal Support (UTS) data) through the TCP/IP network between peer Cisco routers. ALPS phase I provided support for the ALC protocol and the transport of the data from the ASCUs to a reservations system on an IBM mainframe. ALPS phase II provided support for the UTS protocol and the transport of the data from the ASCUs to a reservations system on a Unisys host system.

Figure 214 shows a basic ALPS topology with ALC, UTS, AX.25 and Exchange of Mixed Traffic over X.25 SVCs (EMTOX) protocols. Three major components provide the end-to-end transportation of airline protocol traffic across the network: the P1024B Airline Control (ALC) or P1024C (UTS) protocol, the TCP-based transport protocol, and the AX.25/EMTOX access to the mainframe.

ALPS phase III provides support for Mapping of Airline Traffic over Internet Protocol (MATIP). MATIP is an industry standard protocol for transporting airline protocol traffic across a TCP/IP network. This enhancement enables the end-to-end delivery of ALC and UTS data streams between a Cisco router and the mainframe using TCP/IP. ALPS with MATIP removes the X.25 (AX.25 or EMTOX) requirements for communication with the host reservation system by enabling TCP/IP communication between the router and the airline host reservation system.

Figure 215 shows the basic ALPS topology and the MATIP architecture implemented in Phase III. Three major components provide the end-to-end transportation of airline protocol traffic across the network: the P1024B Airline Control (ALC) or P1024C (UTS) protocol, the TCP/IP-based MATIP protocol conversion, and the TCP/IP access to the mainframe.

Remote routers must have the Cirrus Logic CD2430 chipset on a synchronous serial interface module to connect to the ALC or UTS ASCUs. The CD2430 chipset is supported on the following router platforms:

• Cisco 2520, 2521, 2522, and 2523

• Cisco 2600 series

• Cisco 3600 series

• Cisco 4500

• Cisco 4700

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Note The Cisco 4500 and Cisco 4700 platforms must have a high-density, low-speed serial card installed. Sixteen low-speed ports are available for performing the remote router functions.

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The ALPS feature supports the following RFC and standards:

• RFC 2351, Mapping of Airline Reservation, Ticketing, and Messaging Traffic over IP, May 1998

• P1024B Communication Control Protocol Specification, Societe Internationale de Telecommunications Aeronautiques

• P1024C Communication Control Protocol Specification, Societe Internationale de Telecommunications Aeronautiques

• MATIP Implementation Guide, Societe Internationale de Telecommunications Aeronautiques

ALPS Configuration Task List

The following sections provide configuration tasks for the ALPS feature. Each task in the list indicates if the task is optional or required. The tasks in the "Configuring the Remote Routers" section are the only required tasks for ALPS with MATIP.

• Configuring the Remote Routers (Required)

• Configuring the Data Center Router (Required for EMTOX and AX.25, only)

• Customizing the Service Messages (Optional)

• Customizing the Alarm Notifications (Optional)

• Updating a Circuit (Optional)

• Verifying ALPS (Required)

See the "ALPS Configuration Examples" section for more information.

Configuring the Remote Routers

Note To configure ALPS with MATIP, you must perform the following tasks, only. The tasks apply to EMTOX and AX.25 also.

Perform the tasks in the following sections to configure the ALPS feature on the remote routers:

• Specifying the ALPS Local Peer IP Address

• Specifying the ALPS Remote Peer IP Address

• Specifying the ALPS Circuit

• Specifying Each ASCU

Specifying the ALPS Local Peer IP Address

You must identify an IP address as an ALPS local peer on the remote router. Only one ALPS local peer is permitted on a router.

To specify the ALPS local peer IP address, use the following commands in global configuration mode:

	Command	Purpose
Step 1	alps local-peer ipaddress [promiscuous]	Specifies an IP address to use as the ALPS local peer on the remote router.
Step2	alps keepalive [interval time] [retry count]	Enables TCP keepalives for ALPS TCP peer connections.

Specifying the ALPS Remote Peer IP Address

You must specify a partner IP address (remote peer) on the remote router. The peer connection may be permanent or dynamic (established on demand).

To specify the partner IP address for one or more TCP peer connections to the configured IP address, use the following command in global configuration mode:

Command	Purpose
alps remote-peer ip-addr [protocol {atp | matip-a}] [status-interval interval] [status-retry retries] [dynamic [inact-timer] [no-circuit no-circ-timer]] [tcp-qlen [num]]	Specifies the partner IP address. If you select the ATP protocol, you must configure the data center routers.

Specifying the ALPS Circuit

An ALPS circuit is a communication path across a TCP connection for one or more ASCUs. The ALPS circuit must have a configured association with an ALPS remote peer to establish a connection to the host. Additionally, an ALPS circuit configuration may specify a different remote peer as a backup peer to the host. Each MATIP circuit maps to a single TCP connection. For ATP, ALPS circuits can be multiplexed across to a single TCP connection.

To specify an ALPS circuit, use the following commands, beginning in global configuration mode:

	Command	Purpose
Step1	alps circuit name	Specifies an ALPS circuit at the remote router and enters ALPS circuit submode.
Step2	alps primary-peer ip-addr [backup-peer ip-addr]	Specifies the primary TCP peer and an optional backup peer for this ALPS circuit.
Step3	alps local-hld loc-hld remote-hld rem-hld	Specifies the local high-level designator (HLD) for this ALPS circuit. The remote-hld keyword is not applicable for ALPS with MATIP. The loc-hld is the hld of the device that is being replaced. The rem-hld is the hld of the host mainframe.
Step4	alps hostlink number {ax25 lcn | emtox x121-addr} [winout val1] [winin val2] [ops val3] [ips val4]	Specifies information required to establish an X.25 virtual circuit at the central CPE.
Step5	alps connection-type permanent [retry-timer]	(Optional) Specifies that this circuit should be established when the circuit is enabled.
Step6	alps lifetime-timer timer	(Optional) Specifies how long messages can be queued in the ALPS circuit queue.
Step7	alps service-msg-interval seconds	(Optional) Specifies the interval between the transmission of a service message to an ASCU and the transmission of a PLEASE RETRY message. The PLEASE RETRY message is transmitted only to ASCUs that use circuits with a dynamic connection type.
Step8	alps service-msg-list list	(Optional) Defines the service message list to be used for this circuit.
Step9	alps matip-close-delay time	(Optional) Specifies the interval between the closing and reopening of the MATIP circuit connection.
Step10	alps idle-timer timer	(Optional) Specifies (for dynamic circuits) the length of time that can elapse before an idle circuit is disabled.
Step11	alps mpx {group | single} hdr {a1a2 | none}	(Optional) Specifies the multiplexing and the ASCU identification header for this circuit.
Step12	alps enable-circuit	Enables the circuit.

Specifying Each ASCU

You must configure each ASCU within the context of the serial interface configuration. You must configure ASCU addressing information and association with an ASCU. You can configure the timers, maximum frame sizes, and retry values optional configuration parameters for each ASCU. Appropriate default parameters are used for unspecified parameters. Once you configure the first ASCU, you can configure additional ASCUs using only Steps 8 through 14.

To specify an ASCU, use the following commands, beginning in global configuration mode:

	Command	Purpose
Step1	interface type number	Configures an interface and enters interface configuration mode.
Step2	encapsulation [alc | uts]	Specifies the protocol to be used on the serial interface.
Step3	alps t1 delay	(Optional) Specifies the timeout delay between the transmission of an ALC poll message and the receipt of the first character of the poll message response.
Step4	alps t2 delay	(Optional) Specifies the timeout delay between receipt of the first character of the response to a poll message and the receipt of a Go Ahead message. Applies to ALC, only.
Step5	alps n1 errors	(Optional) Specifies the threshold of consecutive errors logged before an ASCU is declared down.
Step6	alps n2 polls	(Optional) Specifies the number of polls that must be correctly replied to before an ASCU is declared up.
Step7	alps n3 value	(Optional) Specifies the maximum number of retransmissions of an unacknowledged output data message to an ASCU. Applies to UTS, only.
Step8	alps servlim polls	(Optional) Specifies the number of cycles of the active poll list to execute before polling the next ASCU on the inactive poll list.
Step9	alps poll-pause msec	(Optional) Specifies the minimum interval, in milliseconds, between initiations of the polling cycle.
Step10	alps ascu id	Specifies a physical ASCU identity (the ASCU interchange address value for ALC) and enters ALPS ASCU submode.
Step11	alps default-circuit name	Specifies the ALPS circuit that this ASCU uses.
Step12	alps a1-map a1-value a2-map a2-value	Specifies the A1 and A2 logical ASCU identification information.
Step13	alps retry-option [resend | reenter]	(Optional) Specifies the retry option when an ALC message with a bad cyclic check character (CCC) is received.
Step14	alps max-msg-length value	(Optional) Specifies maximum input message length.
Step15	alps error-display number1 number2	(Optional) Specifies where error messages are displayed. For ALC (P1024B), the number1 argument specifies the terminal address where these service messages are sent and the number2 argument specifies the screen line number where service messages are displayed. For UTS (P1024C), the number1 argument specifies the screen line number where service messages are displayed and number2 argument specifies the column number where service messages are displayed.
Step16	alps enable-ascu	Begins polling the ASCU.

Configuring the Data Center Router

NoteThese tasks apply to EMTOX and AX.25, only.

Perform the tasks in the following sections to configure the ALPS feature on the data center router:

• Specifying the ALPS Host Local Peer Address

• Specifying AX.25

• Specifying EMTOX

Specifying the ALPS Host Local Peer Address

You must identify an IP address to use as the ALPS local peer IP address. Only one ALPS host local peer is permitted on a router. The promiscuous option, which allows any remote router to connect, is recommended at the central CPE.

To specify the ALPS host local peer address, use the following command in global configuration mode:

Command	Purpose
alps local-peer ip-address [promiscuous]	Specifies the IP address of the local peer.

Specifying AX.25

To enable AX.25 on an X.25 interface, the ALPS host HLD and hostlink number must be configured and AX.25 must be specified on an X.25 serial interface. At circuit-establishment time, the remote router forwards the host HLD, the logical channel number (LCN), and the hostlink number for the permanent virtual circuit (PVC), to be used for the ASCU group.

To configure AX.25 on an X.25 interface, use the following commands beginning in global configuration mode:

	Command	Purpose
Step1	interface type number	Configures an interface and enters interface configuration mode.
Step2	encapsulation x25 ax25	Specifies a serial interface as an X.25 device.
Step3	alps host-hld hld host-link num {{ax25 [damp-tmr value]} | {emtox x.121 [pseudo-conv]}} [life-tmrvalue]	Enables ALPS on the X.25 interface.

Specifying EMTOX

To enable EMTOX on an X.25 interface, the host HLD and the hostlink number must be configured and EMTOX must be specified on an X.25 serial interface. At circuit-establishment time, the remote router forwards the X.121 address to be used as the calling address in the X.25 call and the host HLD and the hostlink number. If the host performs a call out, a correlation between the X.121 called address and a remote router peer IP address must be configured.

To configure EMTOX on an X.25 interface, use the following commands beginning in global configuration mode:

	Command	Purpose
Step1	interface type number	Configures an interface and enters interface configuration mode.
Step2	encapsulation x25	Specifies a serial interface as an X.25 device.
Step3	alps host-hld hld host-link num {{ax25 [damp-tmr value]} | {emtox x.121 [pseudo-conv]}} [life-tmrvalue]	Enables ALPS on the X.25 interface.
Step4	alps translate x.121-addr ip-addr	Maps an X.121 address to an IP address on a remote peer.

Customizing the Service Messages

You can customize the contents of the service message list. To specify the service message number and the content of the message, use the following command in global configuration mode:

Command	Purpose
alps service-msg-list list number number msg	Specifies service message numbers and content.

Customizing the Alarm Notifications

You can enable and customize alarms (error messages) and SNMP traps. To enable and customize alarms for the ALPS ASCUs, circuits, or peers, use the following commands in global configuration mode:

Command	Purpose
alps enable-alarms ascu [interface id]	Enables alarms for the ALPS ASCUs.
alps enable-alarms circuit [name]	Enables alarms for the ALPS circuits.
alps enable-alarms peer [ip-address]	Enables alarms for the ALPS peers.

Updating a Circuit

You can clear or update the circuits on the ALPS network. If a specific name is entered, the update action will be executed only on a configured circuit with that name; otherwise, the action will be performed on all configured circuits. If the circuit uses the ATP protocol, an update consists of a closing and re-opening of the ALPS circuit (the same action performed when clearing the circuit). If the circuit is a MATIP circuit, the update results in the sending of a configuration update (in the form of a MATIP Session Open command). You can update the circuit only on enabled or active (opened or opening state) ALPS circuits.

To update one or more ALPS circuits, use the following command in EXEC mode:

Command	Purpose
alps update-circuit [name]	Specifies name of circuit to update.

Verifying ALPS

Perform the tasks in the following steps to verify the ALPS feature:

router#show alps ascu
interface    dlc   id   a1   a2   circuit    pkt_tx  pkt_rx  state
---------------------------------------------------------------------------------------
Serial6      ALC   42   60   70   CKT_ALC_1  416     416     UP
Serial6      ALC   45   60   72   CKT_ALC_1  600     600     UP
Serial6      ALC   48   62   78   CKT_ALC_2  0       0       DOWN
Serial7      UTS   21   22   13   CKT_UTS    4830    4830    UP
 

Step 2 Verify that the peer between the router and the host is connected. Enter the show alps peer command and check the state field. OPENED indicates that the circuit is connected. DISCONN indicates that the circuit is disconnected.

router#show alps peers
local_peer : ip_address = 192.168.25.2
 
ip_address     conn_id             state    pkt_t  pkt_rx
---------------------------------------------------------------------------------------
192.168.20.3   MATIP_A_CKT_UTS     OPENED   1023   1023
192.168.70.2   MATIP_A_CKT_ALC_1   OPENED   4852   4757
192.168.70.2   MATIP_A_CKT_ALC_2   OPENED   1      1
192.168.70.3   MATIP_A_CKT_ALC_1   DISCONN  0      0
192.168.70.3   MATIP_A_CKT_ALC_2   DISCONN  0      0
 

Step 3 Verify that the ALPS circuit to the peer host is open and connected. Enter the show alps circuits command and check the state field. OPEN indicates that the circuit is connected. DISCONN indicates that the circuit is disconnected.

router#show alps circuits
 
name        pri_peer       curr_peer      dlc   state  pkt_tx  pkt_rx
---------------------------------------------------------------------------------------
ALC_EMTOX   192.168.45.2   192.168.45.2   ALC   OPEN   944     944
UTS_AX25    192.168.45.2   192.168.45.2   UTS   OPEN   425     425
 

Monitoring and Maintaining ALPS

To monitor the status of the ALPS feature, use the following commands in EXEC mode:

Command	Purpose
show alps ascu [interface] [id] [detail]	Displays the status of the ALPS ASCU.
show alps circuits [peer ip address] [name name] [detail]	Displays the status of the ALPS circuits.
show alps peers [ipaddress addr] [detail]	Displays the status of the ALPS remote peers.

ALPS Configuration Examples

This section provides the following configuration examples:

• ALPS with MATIP Configuration for ALC and UTS Example

• ALPS Configuration for ALC and AX.25 Example

• ALPS Configuration for UTS and EMTOX Example

ALPS with MATIP Configuration for ALC and UTS Example

Figure 216 shows a simple example of a router topology for the ALPS with MATIP feature. The configuration corresponding to this topology follows.

ALC/UTS Router Configuration

(config)# hostname alps-rcpe
(config)# alps local-peer 192.168.25.2
(config)# alps keepalive interval 45 retry 2
(config)# alps remote-peer 192.168.20.3 protocol matip-a dynamic status-interval 60
(config)# alps remote-peer 192.168.70.2 protocol matip-a dynamic 0 no-circuit 10
(config)# alps remote-peer 192.168.70.3 protocol matip-a dynamic 45
(config)# alps enable-alarms peer 192.168.70.2
(config)# alps enable-alarms ascu
! 
(config)# alps circuit CKT_ALC_1
(config-alps-circ)# alps primary-peer 192.168.70.2 backup-peer 192.168.70.3
(config-alps-circ)# alps connection-type permanent
(config-alps-circ)# alps local-hld 2525
(config-alps-circ)# alps enable-circuit
!
(config)# alps circuit CKT_UTS
(config-alps-circ)# alps primary-peer 192.168.20.3
(config-alps-circ)# alps mpx single
(config-alps-circ)# alps idle-timer 90
(config-alps-circ)# alps local-hld 2527
(config-alps-circ)# alps enable-circuit
(config-alps-circ)# alps service-msg-interval 2
!
(config)# interface Loopback0
(config-if)# ip address 192.168.25.2 255.255.255.0
 
(config)# interface Serial0
(config-if)# ip address 210.100.50.2 255.255.255.0
(config-if)# encapsulation frame-relay IETF
(config-if)# frame-relay map ip 210.100.60.2 40
(config-if)# frame-relay map ip 210.100.70.2 50
 
!
 
(config)# interface Serial6
(config-if)# encapsulation alc
(config-if)# alps t1 6
(config-if)# alps t2 8
(config-if)# alps poll-pause 100
(config-if)# clockrate 9600
!
(config-if)# alps ascu 42
(config-alps-ascu)# alps default-circuit CKT_ALC_1
(config-alps-ascu)# alps a1-map 60 a2-map 70
(config-alps-ascu)# alps enable-ascu
!
(config-if)# alps ascu 45
(config-alps-ascu)# alps default-circuit CKT_ALC_1
(config-alps-ascu)# alps a1-map 60 a2-map 72
(config-alps-ascu)# alps enable-ascu
!
(config)# interface Serial7
(config-if)# encapsulation uts
(config-if)# alps n3 4
(config-if)# alps poll-pause 125
(config-if)# clockrate 4800
!
(config-if)# alps ascu 21
(config-alps-ascu)# alps default-circuit CKT_UTS
(config-alps-ascu)# alps a1-map 22 a2-map 13
(config-alps-ascu)# alps enable-ascu
!

ALPS Configuration for ALC and AX.25 Example

Figure 217 shows a simple router topology for the ALPS feature with ALC encapsulation. The configuration for this topology follows.

ALPS Configuration for UTS and EMTOX Example

The following configuration is an example of routing UTS (P1024C) data frames across the network between central and remote equipment.

Remote Router Configuration

(config)# hostname alps-rcpe
(config)# alps local-peer 200.100.25.2
(config)# alps keepalive interval 45 retry 5
(config)# alps remote-peer 200.100.40.2
(config)# alps enable-alarms peer 200.100.40.2
(config)# alps enable-alarms ascu
 
(config)# alps circuit UTS_EMTOX
(config-alps-circ)# alps primary-peer 200.100.40.2
(config-alps-circ)# alps idle-timer 90
(config-alps-circ)# alps local-hld 2525 remote-hld 5050
(config-alps-circ)# alps mpx single
(config-alps-circ)# alps hostlink 6 emtox 1100 ops 512 ips 512
(config-alps-circ)# alps service-msg-interval 2
(config-alps-circ)# alps enable-circuit
 
(config)# interface Loopback0
(config-if)# ip address 200.100.25.2 255.255.255.0
 
(config)# interface Serial0
(config-if)# ip address 200.100.50.2 255.255.255.0
(config-if)# encapsulation frame-relay IETF
(config-if)# frame-relay map ip 200.100.50.3 20
 
(config)# interface Serial1
(config-if)# encapsulation uts
(config-if)# alps n1 5
(config-if)# alps n3 4
(config-if)# alps poll-pause 200
(config-if)# clockrate 4800
!
(config-if)# alps ascu 21
(config-alps-ascu)# alps default-circuit UTS_EMTOX
(config-alps-ascu)# alps a1-map 22 a2-map 13
(config-alps-ascu)# alps enable-ascu
!

Central CPE Configuration

(config)# hostname alps-ccpe
(config)# alps local-peer 200.100.40.2 promiscuous
(config)# alps enable-alarms circuit
!
(config)# interface Loopback0
(config-if)# ip address 200.100.40.2 255.255.255.0
!
(config)# interface Serial0
(config-if)# ip address 200.100.50.3 255.255.255.0
(config-if)# encapsulation frame-relay IETF
(config-if)# clockrate 56000
(config-if)# frame-relay map ip 200.100.50.2 20
!
(config)# interface Serial2
(config-if)# encapsulation x25 dce
(config-if)# alps host-hld 5050 host-link 6 emtox 2222
(config-if)# alps translate 110* 200.100.25.2
(config-if)# clockrate 64000

Posted: Thu Jul 20 10:19:12 PDT 2000
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