📄 rfc2351.txt
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Network Working Group A. Robert
Request for Comments: 2351 SITA
Category: Informational May 1998
Mapping of Airline Reservation, Ticketing,
and Messaging Traffic over IP
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1998). All Rights Reserved.
Security Disclaimer:
This document fails to adequately address security concerns. The
protocol itself does not include any security mechanisms. The
document notes that traffic can be authenticated based on external
mechanisms that use static identifiers or what are apparently clear-
text passwords, neither of which provide sound security. The
document notes in general terms that traffic can be secured using
IPSEC, but leaves this form of sound security strictly optional.
Abstract
This memo specifies a protocol for the encapsulation of the airline
specific protocol over IP.
Table of Conents
1. INTRODUCTION 2
2. TERMINOLOGY & ACRONYMS 4
3. LAYERING 7
4. TRAFFIC IDENTIFICATION 7
5. TCP PORT ALLOCATION 8
6. MATIP SESSION ESTABLISHMENT 8
7. OVERALL PACKET FORMAT FOR TYPE A & TYPE B 9
8. MATIP FORMAT FOR TYPE A CONVERSATIONAL TRAFFIC 10
8.1 Control Packet Format 10
8.1.1 Session Open format (SO) 10
8.1.2 Open Confirm format (OC) 12
8.1.3 Session Close (SC) 14
8.2 Data Packet Format 14
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RFC 2351 MATIP May 1998
9. MATIP FORMAT FOR TYPE A HOST-TO-HOST TRAFFIC 15
9. 1 Control Packet Format 15
9.1.1 Session Open format (SO) 15
9.1.2 Open Confirm format (OC) 17
9.1.3 Session Close (SC) 17
9.2 Data Packet Format 18
10. MATIP FORMAT FOR TYPE B TRAFFIC 19
10.1 Control packet format 19
10.1.1 Session Open format (SO) 19
10.1.2 Open confirm format (OC) 20
10.1.3 Session Close (SC) 21
10.2 Data packet format 21
11. SECURITY CONSIDERATIONS 22
12. AUTHOR'S ADDRESS 22
13. FULL COPYRIGHT STATEMENT 23
1. Introduction
The airline community has been using a worldwide data network for
over 40 years, with two main types of traffic:
Transactional traffic
This is used typically for communication between an airline office
or travel agency and a central computer system for seat
reservations and ticket issuing. A dumb terminal or a PC accesses
the central system (IBM or UNISYS) through a data network.
This traffic is also called TYPE A and is based on real-time
query/response with limited protection, high priority and can be
discarded. The user can access only one predetermined central
computer system. In case of no response (data loss), the user can
duplicate the request.
Messaging
This is an e-mail application where real-time is not needed.
However a high level of protection is required. The addressing
scheme uses an international format defined by IATA and contains
the city and airline codes.
This traffic is also called TYPE B and is transmitted with a high
level of protection, multi-addressing and 4 levels of priority.
The detailed formats for TYPE A and TYPE B messages are defined in
the IATA standards.
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RFC 2351 MATIP May 1998
At the bottom level, synchronous protocols have been built since
1960's and well before the OSI and SNA standards.
At present, there is a big number of legacy equipment installed in
thousands of airline offices around the world. Many airlines do not
have immediate plans to replace their terminals with more modern
equipment using open standards. They are in search of more economical
ways for connecting these terminals to the present reservation
system.
Most airlines are willing to migrate from airline specific protocols
to standardized protocols in order to benefit from the lower cost of
new technologies, but the migration has been slow done to the
following factors:
- Applications have not been migrated.
- Dumb terminals using airline protocols P1024B (IBM ALC) or P1024C
(UNISYS UTS) are still numerous.
There are currently many different proprietary solutions based on
gateways available to take advantage of low cast networking, but they
are not scalable and cannot interact.
In the future, TCP/IP will be more commonly used as a common
transport means for traffic types because:
- TCP/IP is the standard protocol of UNIX based applications
- TCP/IP stacks are inexpensive
- TCP/IP is used on intranets.
The purpose of this RFC is to define the mapping of the airline
traffic types over TCP/IP. The airlines implementing it in their
systems should have a TCP/IP stack to enable the traffic exchange
below:
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RFC 2351 MATIP May 1998
!----! ( )
! !----------( )
!----! ( )
Type B HOST ( NETWORK )
( )
( ) !---o
!----! ( )--------! D !---o Type A stations
!----!----------( ) !---o
!----! ( )
TYPE A HOST !
!
!
!
--------
! !
--------
Network Messaging System
(D) : Gateway TYPE A router
The different airline traffic flows concerned by this RFC are:
- TYPE A Host / Terminal
- TYPE A Host / TYPE A host
- TYPE B Host / Network messaging System
In the case of dumb terminals, a conversion is required on the
terminal side in order to have an IP connection between the host and
the router. However, the IP connection is directly between the
central airline host and the intelligent workstation if the latter
has a direct connection to the network, a TCP/IP stack and a terminal
emulation
2. Terminology & Acronyms
ALC
Airline Line Control: IBM airline specific protocol (see P1024B)
ASCII
American Standard Code for Information Interchange
ASCU
Agent Set Control Unit: Cluster at the user side.
AX.25
Airline X.25: Airline application of the X.25 OSI model (published by
IATA)
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RFC 2351 MATIP May 1998
BAUDOT
Alphabet defined in ITU-T Number 5. BAUDOT uses 5 bits. Padded BAUDOT
uses 7 bits with the Most significant bit (bit 7) for the parity and
the bit 6 equal to 1.
BATAP
Type B Application to Application Protocol. Protocol to secure the
TYPE B traffic. It was specified by SITA and is now published by IATA
(SCR Vol. 3)
EBCDIC
Extended Binary Coded Decimal Interchange Code
Flow ID Traffic
Flow identifier used in host to host traffic to differentiate
traffic flow types.
HLD
High Level Designator: Indicates the entry or exit point of a block
in the network.
IA
Interchange Address: ASCU identifier in P1024B protocol.
IATA
International Air Transport Association
IP
Internet Protocol
IPARS
International Program Airline Reservation System: IPARS code is used
in ALC
HTH
Host to Host (traffic).
LSB
Least Significant Bit
MATIP
Mapping of Airline Traffic over Internet Protocol
MSB
Most Significant Bit
OC
Open Confirm (MATIP command)
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RFC 2351 MATIP May 1998
OSI
Open Standard Interface
P1024B
SITA implementation of the ALC, the IBM airlines specific protocol.
It uses 6-bit padded characters (IPARS) and IA/ TA for physical
addressing.
P1024C
SITA implementation of the UTS, the UNISYS terminal protocol. It uses
7-bit (ASCII) characters and RID/ SID for physical addressing.
RFU
Reserved for Future Use
RID
Remote Identifier: ASCU identifier in P1024C protocol.
SC
Session Close (MATIP command)
SCR
System and Communication Reference. (IATA document)
SID
Station Identifier: Terminal identifier in P1024C protocol.
SITA
Societe International de Telecommunications Aeronautiques
SO
Session Open (MATIP command)
TA
Terminal Address: Terminal identifier in P1024B protocol.
TCP
Transport Control Protocol
TYPE A Traffic
Interactive traffic or host to host
TYPE B Traffic
Messaging traffic in IATA compliant format with high level of
reliability
UTS
Universal Terminal System by Unisys: (see P1024C)
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RFC 2351 MATIP May 1998
3. LAYERING
MATIP is an end to end protocol. Its purpose is to have a mapping
standard between the TCP layer and the airline application without
any routing element.
+-------------------------------+
|Airline TYPE A | Airline TYPE B|
| | Application |
| |---------------|
| Application | BATAP |
+-------------------------------+
| MATIP A | MATIP B |
+-------------------------------+
| T.C.P |
+-------------------------------+
| I.P |
+-------------------------------+
| MEDIA |
+-------------------------------+
4. TRAFFIC IDENTIFICATION
In TYPE A conversational traffic, the airline host application
recognizes the ASCU due to 4 bytes (H1, H2, A1, A2). These bytes are
assigned by the host and are unique per ASCU. Thus, a host can
dynamically recognize the ASCU independent of IP address.
H1 H2 A1 A2 bytes follow one of the three cases below:
- A1,A2 only are used and H1H2 is set to 0000.
- H1,H2 identify the session and A1A2 the ASCU inside the session.
- H1,H2,A1,A2 identify the ASCU.
The first two cases are fully compatible with the AX.25 mapping where
H1H2 may be equivalent to the HLD of the concentrator, i.e., 2 bytes
hexadecimal. The third rule allows more flexibility but is not
compatible with AX.25.
In TYPE A host to host traffic the identification field is also
present and is equal to 3 bytes H1 H2 Flow ID (optional). H1H2 are
reserved for remote host identification (independently of the IP
address) and must be allocated bilaterally.
In Type B traffic, identification of End Systems may be carried out
by the use of HLDs, or directly by the pair of IP addresses.
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RFC 2351 MATIP May 1998
5. TCP PORT ALLOCATION
IANA (Internet Assigned Numbers Authority) has allocated the
following ports for MATIP TYPE A and TYPE B traffic:
MATIP Type A TCP port = 350
MATIP Type B TCP port = 351
Therefore the traffic type A or B is selected according to the TCP
port.
6. MATIP SESSION ESTABLISHMENT
Prior to any exchange between two applications, a single MATIP
session is established above the TCP connection in order to identify
the traffic characteristic such as:
- Subtype of traffic for TYPE A (Type A host to host or Type A
conversational )
- Multiplexing used (for Type A)
- Data header
- Character set
A separate session and TCP connection must be established for each
set of parameters (e.g., P1024B, P1024C traffic between two points
needs two separate sessions).
The establishment of a MATIP session can be initiated by either side.
No keep-alive mechanism is defined at MATIP level. Session time out
relies on the TCP time-out parameters.
There are three commands defined to manage the MATIP session:
- Session Open (SO) to open a session.
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