Network Working Group A. Robert

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

Robert Informational [Page 1]

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.

Robert Informational [Page 2]

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:

Robert Informational [Page 3]

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)

Robert Informational [Page 4]

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)

Robert Informational [Page 5]

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)

Robert Informational [Page 6]

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.

Robert Informational [Page 7]

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.
- Open Confirm (OC) to confirm the SO command.
- Session close (SC) to close the current session.

A MATIP session can be up only if the associated TCP connection is
up. However it is not mandatory to close the TCP connection when
closing the associated MATIP session.

Typical exchange is:

TCP session establishment

Session Open --------->
<----------- Open confirm
data exchange
---------------------->

Robert Informational [Page 8]

RFC 2351 MATIP May 1998

<-------------------------
.
.
.
Session Close ----------------->
.
.
.
<------------------------- Session Open
Open confirm ------------------->
data exchange
<-------------------------
---------------------->

The Session Open command may contain configuration elements. An
Session Open command received on a session already opened (i.e., same
IP address and port number) will automatically clear the associated
configuration and a new configuration will be set up according to the
information contained in the new open session command.

As illustrated above, the open and close commands are symmetrical.

For type A conversational traffic, the SO and OC commands contain
information for the identification of the ASCUs and the session.
ASCUs are identified within a session by two or 4 bytes. A flag is
set to indicate if the ASCU is identified by 4 bytes (H1H2A1A2) or by
2 bytes (A1A2). In the latter case, H1H2 is reserved for session
identification.

The SO command is sent to open the MATIP session. In Type A
conversational it may contains the list of ASCUs configured in this
session.

The OC command confirms the SO command. It can refuse or accept it,
totally or conditionally. In Type A, it contains the list of the
ASCUs either rejected or configured in the session.

7. OVERALL PACKET FORMAT FOR TYPE A & TYPE B

The first 4 bytes of the MATIP header follow the following rules.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |C| Cmd | length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Robert Informational [Page 9]

RFC 2351 MATIP May 1998

Ver
The `Ver' (Version) field represents the version of the MATIP. It
must contain the value 001 otherwise the packet is considered as
invalid.

C
Identifies a CONTROL packet.
When set to 1, the packet is a Control packet
When set to 0, the packet is a Data packet

Cmd
This field identifies the control command if the flag C is set to 1.

Length
This field indicates the number of bytes of the whole packet, header
included.

Notes : Fields identified as optional (Opt) are not transmitted if
not used.

8. MATIP FORMAT FOR TYPE A CONVERSATIONAL TRAFFIC

8. 1 Control Packet Format

There are 3 control packets to open or close the session at the MATIP
level.

8.1.1 Session Open format (SO)

To be able to identify the session and before sending any data
packets, a Session Open command is sent. It can be initiated by
either side. In case of collision, the open session from the side
having the lower IP address is ignored.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 1 0| length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0|0 1|0| CD | STYP |0 0 0 0| RFU |MPX|HDR| PRES. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| H1 | H2 | RFU |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | RFU | Nbr of ASCUs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nbr of ASCUs | ASCU list (opt) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Robert Informational [Page 10]

RFC 2351 MATIP May 1998

RFU
Reserved for future use. Must be set to zero.

CD
This field specifies the Coding
000 : 5 bits (padded baudot)
010 : 6 bits (IPARS)
100 : 7 bits (ASCII)
110 : 8 bits (EBCDIC)
xx1 : R.F.U

STYP
This is the traffic subtype (type being TYPE A).
0001 : TYPE A Conversational

MPX
This flag specifies the multiplexing used within the TCP session.
Possible values are:
00 : Group of ASCU with 4 bytes identification per ASCU (H1H2A1A2)
01 : Group of ASCUs with 2 bytes identification per ASCU (A1A2)
10 : single ASCU inside the TCP session.

HDR
This field specifies which part of the airline's specific address is
placed ahead of the message texts transmitted over the session.
Possible values are:
00 : ASCU header = H1+H2+A1+A2
01 : ASCU Header = A1+A2
10 : No Header
11 : Not used

The MPX and HDR must be coherent. When ASCUs are multiplexed, the data
must contain the ASCU identification. The table below summarizes the
allowed combinations:

+--------------------------+
| MPX | 00 | 01 | 10 |
+--------------------------+
| HDR | |
| 00 | Y | Y | Y |
| 01 | N | Y | Y |
| 10 | N | N | Y |
+--------------------------+

Robert Informational [Page 11]

RFC 2351 MATIP May 1998

PRES
This field indicates the presentation format
0001 : P1024B presentation
0010 : P1024C presentation
0011 : 3270 presentation

H1 H2
These fields can logically identify the session if MPX is not equal to
00. When this field is not used, it must be set to 0. If used in
session (MPX <> 0) with HDR=00, H1H2 in data packet must have the same
value as set in SO command.

Nbr of ASCUs
Nbr_of_ASCUs field is mandatory and gives the number of ASCUs per
session. A 0 (zero) value means unknown. In this case the ASCU list is
not present in the `Open Session' command and must be sent by the
other end in the `Open Confirm' command.

ASCU LIST
Contains the list of identifier for each ASCU. If MPX=00 it has a
length of four bytes (H1H2A1A2) for each ASCU, otherwise it is two
bytes (A1A2).

8.1.2 Open Confirm format (OC)

The OC (Open Confirm) command is a response to an SO (Session Open)
command and is used to either refuse the session or accept it
conditionally upon checking hte configuration of each ASCU.

In case of acceptance, the OC indicates the number and the address of
the rejected ASCUs, if any. Alternatively, it indicates the list of
ASCUs configured for that MATIP session if the list provided by the
SO command was correct or the number of ASCUs configured in the
session was unknown (n. of ASCU equals 0).

8.1.2.1 Refuse the connection

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 1|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| cause |
+-+-+-+-+-+-+-+-+

Cause
This field indicates the reason for the MATIP session refusal:

Robert Informational [Page 12]

RFC 2351 MATIP May 1998

0 0 0 0 0 0 0 1 : No Traffic Type matching between Sender &
Recipient
0 0 0 0 0 0 1 0 : Information in SO header incoherent

1 0 0 0 0 1 0 0
up to : Application dependent
1 1 1 1 1 1 1 1

Other values reserved.

8.1.2.2 Accept the connection

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 1| length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 R 0 0 0 0 0| Nbr of ASCUs |Nbr of ASCU(opt| ASCU LIST |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

R
Flag indicating an error in the ASCU configuration provided in the SO
command.

NBR of ASCUs
If the MPX value is equal to 00 in the SO command, this field is two
bytes long. Otherwise, it is one byte.
If the R flag is set, the Nbr_of_ASCUs field represents the number of
ASCUs in error. Otherwise, it indicates the number of ASCUs configured
for that MATIP session.

Notes: The length of this field is either one or two bytes. In the SO
command, the length is always two bytes. This discrepancy comes from
backward compatibility with AX25 (see chapter 4). In the SO command,
it is possible to use a free byte defined in the AX25 call user data.
Unfortunately, there is no such free byte in the AX25 clear user
data.

ASCU LIST
Depending on the R flag, this field indicates the list of ASCUs (A1A2
or H1H2A1A2) either in error or within the session.

Robert Informational [Page 13]

RFC 2351 MATIP May 1998

8.1.3 Session Close (SC)

The SC (Session Close) command is used to close an existing MATIP
session.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 0|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Close Cause |
+-+-+-+-+-+-+-+-+

Close Cause
Indicates the reason for the session closure:

0 0 0 0 0 0 0 0 : Normal Close

1 0 0 0 0 1 0 0
up to : Application dependent
1 1 1 1 1 1 1 1

Other values reserved.

8.2 Data Packet Format

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |0|0 0 0 0 0 0 0| length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ID (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Payload |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ID
This field is optional and has a different length and format
according to the value of HDR, PRES indicated during the session
establishment.

Robert Informational [Page 14]

RFC 2351 MATIP May 1998

+------------------------------+-------------------------------+
|HDR | PRES = P1024B and 3270 | PRES = P1024C |
+------------------------------+-------------------------------+
|00 |ID = 4 bytes H1-H2-A1-A2 | ID = 5 bytes H1-H2-A1-0x01-A2 |
+------------------------------+-------------------------------+
|01 |ID = 2 bytes A1-A2 | ID = 3 bytes A1-0x01-A2 |
+------------------------------+-------------------------------+
|10 |ID = 0 bytes | ID = 0 bytes |
+------------------------------+-------------------------------+

H1, H2 value must match the value given in the SO command if MPX is
different from 0.

Payload
payload begins with the terminal identification:
- One byte Terminal identifier (TA) in P1024B
- Two bytes SID/DID Terminal identifier in P1024C.

9. MATIP FORMAT FOR TYPE A HOST-TO-HOST TRAFFIC

9. 1 Control Packet Format

There are 3 control packets to open or close the session at the MATIP
level.

9.1.1 Session Open format (SO)

To be able to identify the session and before sending any data
packet, a Session Open command is sent. It can be initiated by either
side. In case of collision, the open session from the side having the
lower IP address is ignored.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 1 0| length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0|0 1|0| CD | STYP |0 0 0 0| RFU |MPX|HDR|0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| H1 | H2 | RFU |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow ID(opt)|
+-+-+-+-+-+-+-+-+

RFU
Reserved for future use. Must be set to zero.

Robert Informational [Page 15]

RFC 2351 MATIP May 1998

CD
This field specifies the Coding, as defined in section 8.1.1.1.

STYP
This is the traffic subtype (type being Type A).
0010 : TYPE A IATA Host to Host
1000 : SITA Host to Host

MPX
This flag specifies the multiplexing used within the MATIP session in
TYPE A SITA host to host. Possible values are:

00 : irrelevant
01 : multiple flow inside the TCP connection
10 : single flow inside the TCP connection

HDR
This field specifies which part of the airline's specific address is
placed ahead of the message text transmitted over the session.
Possible values are:

00 : used in TYPE A SITA Host to Host Header = H1+H2+Flow ID
01 : used in TYPE A SITA Host to Host Header = Flow ID
10 : No Header (default for IATA host to Host)
11 : Not used

The MPX and HDR must be coherent. When flow are multiplexed, the data
must contain the flow identification. The table below summarizes the
possible combinations:

+---------------------+
| MPX | 01 | 10 |
+---------------------+
| HDR | | |
| 00 | Y | Y |
| 01 | Y | Y |
| 10 | N | Y |
+---------------------+

H1 H2
These fields can be used to identify the session. When this field is
not used, it must be set to 0. If HDR=00, H1H2 in data packet must
have the same value as set in SO command.

Flow ID
This field is optional and indicates the Flow ID (range 3F - 4F Hex).

Robert Informational [Page 16]

RFC 2351 MATIP May 1998

9.1.2 Open Confirm format (OC)

The OC (Open Confirm) command is a response to an SO (Session Open)
command and is used to either refuse the session or accept it.

9.1.2.1 Refuse the connection

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 1|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| cause |
+-+-+-+-+-+-+-+-+

Cause
This field indicates the reason for the MATIP session refusal

0 0 0 0 0 0 0 1 : No Traffic Type matching between Sender &
Recipient
0 0 0 0 0 0 1 0 : Information in SO header incoherent

1 0 0 0 0 1 0 0
up to : Application dependent
1 1 1 1 1 1 1 1

Other values reserved.

9.1.2.2 Accept the connection

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 1|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+

9.1.3 Session Close (SC)

The SC (Session Close) command is used to close an existing MATIP
session.

Robert Informational [Page 17]

RFC 2351 MATIP May 1998

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 0|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Close Cause |
+-+-+-+-+-+-+-+-+

Close Cause
Indicates the reason for the session closure:

0 0 0 0 0 0 0 0 : Normal Close

1 0 0 0 0 1 0 0
up to : Application dependent
1 1 1 1 1 1 1 1

Other values reserved

9.2 Data Packet Format

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |0|0 0 0 0 0 0 0| length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ID (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Payload |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ID
This field is optional and has a different length and format
according to the value of HDR indicated during the session
establishment.

+-------------------------------+
|HDR | I.D. |
+-------------------------------+
|00 |ID = 3 bytes H1-H2 FLOW ID|
+-------------------------------+
|01 |ID = FLOW ID |
+-------------------------------+
|10 |ID nor present |
+-------------------------------+

Robert Informational [Page 18]

RFC 2351 MATIP May 1998

Payload packet
The payload format is relevant to the MATIP layer. It is formatted
according to the IATA host to host specifications and agreed
bilaterally by the sender and the receiver.

10. MATIP FORMAT FOR TYPE B TRAFFIC

10.1 Control packet format

There are 3 control packets used to open or close the session at the
MATIP level for exchanging Type B data

10.1.1 Session Open format (SO)

Before sending any data packets, it is recommended to let the systems
establishing a session check that they are indeed able to communicate
(i.e., Both systems agree on the characteristics of the traffic that
will cross the connection). For this purpose, a two way handshake,
using the Session commands defined hereafter, is performed
immediately after the establishment of the TCP level connection.
Either side can initiate this procedure. In case of collision, the
open session from the side having the lower IP address is ignored.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 1 0| length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0| C D | PROTEC| BFLAG | Sender HLD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Recipient HLD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Length
This field indicates the number of bytes of the whole command, header
included. The only possible values are equal to 6 bytes or 10 bytes.

CD
This field specifies the Coding, as defined in section 8.1.1.1.

PROTEC
Identifies the end to end Messaging Responsibility Transfer protocol
used.
0010: BATAP
All other values available.

BFLAG (X means `do not care'

Robert Informational [Page 19]

RFC 2351 MATIP May 1998

X X 0 0 means that the fields `Sender HLD, Recipient HLD' do not exist
in this packet. In this case, the exact length of the packet is 6
Bytes.

X X 1 0 means that the `Sender HLD, Recipient HLD' are carried
respectively in bytes 9,10 and 11,12 of this packet. In this
case, the exact length of the packet is 10 Bytes.

0 0 X X means that the connection request has been transmitted from a
host (Mainframe system)

0 1 X X means that the connection request has been transmitted from a
gateway)

Sender HLD
HLD of the Type B System sending the Session Open.

Recipient HLD
HLD of the Type B system to which session opening is destined.

10.1.2 Open confirm format (OC)

The OC (Open Confirm) command is a response to an SO (Session Open)
command and is used to either refuse the session or accept it.

10.1.2.1 Refuse the connection

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 1|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|1| Cause |
+-+-+-+-+-+-+-+-+

Length of this packet is 5 Bytes.

Cause
Indicates the cause of the rejection

0 0 0 0 0 1 : No Traffic Type matching between Sender & Recipient
0 0 0 0 1 0 : Information in SO header incoherent
0 0 0 0 1 1 : Type of Protection mechanism are different
0 0 0 1 0 0 up to 1 1 1 1 1 1 : R.F.U

Robert Informational [Page 20]

RFC 2351 MATIP May 1998

10.1.2.2 Accept the connection

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 1|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+

Length of this packet is 5 Bytes.

10.1.3 Session Close (SC)

The SC (Session Close) command is used to close an existing MATIP
session.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |1|1 1 1 1 1 0 0|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Close Cause |
+-+-+-+-+-+-+-+-+

Close Cause
Indicates the reason for the session closure:
0 0 0 0 0 0 0 0 : Normal Close
1 0 0 0 0 1 0 0 up to 1 1 1 1 1 1 1 1 : Application dependent

Other values reserved

10.2 Data packet format

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0| Ver |0|0 0 0 0 0 0 0| length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Payload |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Length
This field indicates the number of bytes of the whole packet, header
included.

Robert Informational [Page 21]

RFC 2351 MATIP May 1998

Payload
Type B message formatted according to the IATA standard and
conforming to the rules of the accessed TYPE B service

11. Security Considerations

The security is a very sensitive point for airline industry. Security
for the MATIP users can take place at different levels:

The ASCU must be defined to enable the session with the host
application. The control can be achieved in two ways: either the ASCU
address (H1 H2 A1 A2) is defined at the application level by the
means of a static configuration, or the ASCU is identified by a User
ID / password. In most cases, the User ID and Password are verified
by a dedicated software running in the central host. But they can
also be checked by the application itself.

The MATIP sessions being transported over TCP/IP, It can go through a
firewall. Depending on the firewall level, the control can be
performed at network (IP addresses) or TCP application layer.

For higher level of security all compliant implementations MAY
implement IPSEC ESP for securing control packets. Replay protection,
the compulsory cipher suite for IPSEC ESP, and NULL encryption MAY be
implemented. Optionally, IPSEC AH MAY also be supported. All
compliant implementations MAY also implement IPSEC ESP for protection
of data packets. Replay prevention and integrity protection using
IPSEC ESP mandated cipher suit MAY be implemented. NULL encryption
also MAY be supported. Other IPSEC ESP required ciphers MAY also be
supported.

12. Author's Address

Alain Robert
S.I.T.A.
18, rue Paul Lafargue
92904 PARIS LA DEFENSE 10
FRANCE

Phone: 33 1 46411491
Fax: 33 1 46411277
EMail: [email protected]

Robert Informational [Page 22]

RFC 2351 MATIP May 1998

13. Full Copyright Statement

Copyright (C) The Internet Society (1998). All Rights Reserved.

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Robert Informational [Page 23]