ISO 8327:1987
(Main)Information processing systems — Open Systems Interconnection — Basic connection oriented session protocol specification
Information processing systems — Open Systems Interconnection — Basic connection oriented session protocol specification
Systèmes de traitement de l'information — Interconnexion de systèmes ouverts — Protocole de session en mode connexion
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Standards Content (Sample)
IS0
INTERNATIONAL STANDARD
8327
First edition
1987-08-15
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXAYHAPOAHAR OPrAHM3AL(Mfl il0 CTAHAAPTM3AL(MM
Information processing systems - Open Systems
Interconnection - Basic connection oriented session
protocol specification
Systèmes de traitement de l'information - Interconnexion de systèmes ouverts - Protocole
de session en mode connexion
Leference number
SO 8327 : 1987 (E)
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Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of
national standards bodies (IS0 member bodies). The work of preparing International
StandardKis normally carried out through IS0 technical committees. Each member
body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the IS0 Council. They are approved in accordance with IS0 procedures requiring at
least 75 % approval by the member bodies voting.
International Standard IS0 8327 was prepared by Technical Committee ISO/TC 97,
Information processing systems.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
@ International Organization for Standardization, 1987 O
Printed in Switzerland
ii
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IS0 8327 : 1987 (E)
Contents
Page
O Introduction . 1
1 Scope and field of application . 2
2 References . 2
Section one : General
3 Definitions . 3
4 Symbols and abbreviations . 4
4.1 Dataunits . 4
4.2 SFDU fields . 4
4.3 Timer variables . 4
4.4 Miscellaneous . 4
4
4.5 Local variables .
5 Overview of the session protocol . 4
5.1 Model of the Session Layer . 4
4
5.2 Services provided by the Session Layer .
5.3 Services assumed from the Transport Layer . 4
5.4 Functions of the session layer . 8
5.4.1 Overview of functions . 8
8
5.4.2 Connection establishment phase .
5.4.3 Data transfer phase . 8
5.4.4 Connection release phase . 8
5.5 Functional units . 9
5.5.1 Kernel functional unit . . 9
5.5.2 Negociated release functional unit . 9
5.5.3 Half-duplex functional unit . 9
5.5.4 Duplex functional unit . 9
5.5.5 Expedited data functional unit . 9
5.5.6 Typed data functional unit . 9
5.5.7 Capability data exchange functional unit . 9
5.5.8 Minor synchronize functional unit .
9
5.5.9 Major synchronize functional unit . 9
5.5.10 Resynchronize functional unit . 9
5.5.11 Exceptions functional unit . 9
5.5.12 Activity management functional unit . 9
5.6 Tokens . 9
...
111
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IS0 8327 : 1987 (E)
5.7 Negotiation .
12
5.7.1 Negotiation of functional units . 12
5.7.2 Negotiation of initial token settings .
12
5.7.3 Negotiation of initial serial number . 12
5.7.4 Negotiation of version number .
12
5.7.5 Negotiation of maximum TSDU size . 12
5.8 Localvariables .
12
5.8.1 Vact .
12
5.8.2 Vnextact . 12
5.8.3 V(A) .
12
5.8.4 V(M) .
12
5.8.5 V(R) . 12
5.8.6 Vsc . 12
Section two : Session protocol specification
6 Use of the transport service .
14
6.1 Assignment of a session connection to the transport connection . 14
6.1.1 Purpose .
14
6.1.2 Transport service primitives .
14
6.1.3 SPDUsused . 14
6.1.4 Description .
14
6.2 Reuse of the transport connection . 14
6.2.1 Purpose . 14
6.2.2 Transport service primitives . 14
6.2.3 SPDUsused .
14
6.2.4 Description . 14
6.3 Use of transport normal data .
14
6.3.1 Purpose .
14
6.3.2 Transport service primitives . . 15
6.3.3 SPDUsused . .
15
6.3.4 Transfer of SPDUs . . 15
6.3.5 Segmenting . .
15
6.3.6 Maximum TSDU size . .
15
6.3.7 Concatenation . . 15
6.4 Use of transport expedited data . 19
6.4.1 Purpose .
19
6.4.2 Transport service primitives . 19
6.4.3 SPDUsused .
19
6.4.4 Description .
19
6.5 Flowcontrol . 19
Transportdiçconnection .
6.6 19
6.6.1 Purpose .
19
6.6.2 Transport service primitives . 19
6.6.3 SPDUsused .
19
6.6.4 Description .
19
7 Elements of procedure related to SPDUs . 19
7.1 CONNECT SPDU .
19
iv
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IS0 8327 : 1987 (E)
7.2 ACCEPTSPDU . 20
7.3 REFUSESPDU . 21
7.4 FINISHSPDU . 22
7.5 DISCONNECTSPDU . 22
7.6 NOT FINISHED SPDU . 22
7.7 ABORTSPDU . 22
7.8 ABORT ACCEPT SPDU . 23
7.9 DATA TRANSFER SPDU . 23
7.10 EXPEDITED SPDU . 24
7.11 TYPED DATA SPDU . 24
7.12 CAPABILITY DATA SPDU . 25
7.13 CAPABILITY DATA ACK SPDU . 25
7.14 GIVE TOKENS SPDU . 25
7.15 PLEASE TOKENS SPDU . 25
7.16 GIVE TOKENS CONFIRM SPDU . 26
7.17 GIVE TOKENS ACK SPDU . 26
7.18 MINOR SYNC POINT SPDU . 26
7.19 MINOR SYNC ACK SPDU . 26
7.20 MAJOR SYNC POINT SPDU . 27
7.21 MAJOR SYNC ACK SPDU . 27
7.22 RESYNCHRONIZE SPDU . 27
7.23 RESYNCHRONIZE ACK SPDU . 28
7.24 PREPARESPDU . 29
7.25 EXCEPTION REPORT SPDU . 30
7.26 EXCEPTION DATA SPDU . 30
7.27 ACTIVITY START SPDU . 31
7.28 ACTIVITY RESUME SPDU . 31
7.29 ACTIVITY INTERRUPTSPDU . 31
7.30 ACTIVITY INTERRUPTACK SPDU . 32
7.31 ACTIVITY DISCARD SPDU . 32
7.32 ACTIVITY DISCARD ACK SPDU . 32
7.33 ACTIVITYENDSPDU . 33
7.34 ACTIVITY END ACK SPDU . 33
8 Structureand encoding of SPDUs . 33
8.1 TSDUstructure . 33
8.2 SPDUstructure . 34
8.2.1 SPDUs . 34
8.2.2 PGIunits . 34
8.2.3 Plunits . 36
8.2.4 Identifier fields . 36
8.2.5 Length indicator field . 36
8.2.6 Parameter fields . 36
8.2.7 Parameter values . 36
8.2.8 User information fields . 36
V
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IS0 8327 : 1987 (E)
37
8.3 SPDU identifiers and associated parameter fields .
8.3.1 CONNECT (CN) SPDU . 37
39
8.3.2 ACCEPT (AC) SPDU .
40
8.3.3 REFUSE (RF) SPDU .
8.3.4 FINISH (FN) SPDU . 41
42
8.3.5 DISCONNECT (DN) SPDU .
42
8.3.6 NOT FINISHED (NF) SPDU .
8.3.7 ABORT (AB) SPDU . 42
43
8.3.8 ABORT ACCEPT (AA) SPDU .
8.3.9 DATATRANSFER (DT) SPDU . 43
43
8.3.10 EXPEDITED (EX) SPDU .
44
8.3.11 TYPED DATA (TD) SPDU .
44
8.3.12 CAPABILITY DATA (CD) SPDU .
44
8.3.13 CAPABILITY DATA ACK (CDA) SPDU .
45
8.3.14 GIVETOKENS (GT) SPDU .
45
8.3.15 PLEASETOKENS (PT) SPDU .
46
8.3.16 GIVE TOKENS CONFIRM (GTC) SPDU .
46
8.3.17 GIVE TOKENS ACK (GTA) SPDU .
46
8.3.18 MINOR SYNC POINT(MIP) SPDU .
46
8.3.19 MINOR SYNCACK (MIA) SPDU .
47
8.3.20 MAJOR SYNC POINTACK (MAP) SPDU .
47
8.3.21 MAJOR SYNC ACK (MAA) SPDU .
48
8.3.22 RESYNCHRONIZE (RS) SPDU .
48
8.3.23 RESYNCHRONIZE ACK (RA) SPDU .
49
8.3.24 PREPARE (PR) SPDU .
49
8.3.25 EXCEPTION REPORT (ER) SPDU .
50
8.3.26 EXCEPTION DATA (ED) SPDU .
50
8.3.27 ACTIVITY START (AS) SPDU .
50
8.3.28 ACTIVITY RESUME (AR) SPDU .
51
8.3.29 ACTIVITY INTERRUPT (Al) SPDU .
52
8.3.30 ACTIVITY INTERRUPTACK (AIA) SPDU .
52
8.3.31 ACTIVITY DISCARD (AD) SPDU .
52
8.3.32 ACTIVITY DISCARD ACK (ADA) SPDU .
52
8.3.33 ACTIVITY END (AE) SPDU .
52
8.3.34 ACTIVITY END ACK (AEA) SPDU .
Section three : Conformance
9 Conformance to this International Standard . 53
Annexes
A Statetables . 54
B Relationship to CCllT Recommendation T.62 encoding . 87
PGI and PIS reserved for use by CCllT Recommendation T.62 . 90
C
D Corrections incorporated in IS0 8327 : 1987 . 91
vi
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IS0 8327 : 1987 (E)
INTERNATIONAL STANDARD
Information processing systems - Open Systems
Interconnection - Basic connection oriented session
protocol specification
O Introduction c) as part of an agreement for the admittance of systems
into the open systems environment;
This International Standard is one of a set of International Stan-
dards produced to facilitate the interconnection of computer d) as a refinement to tbe understanding of OSI.
systems. The set of International Standards covers the services
e and protocols required to achieve such interconnection. As it is expected that the initial users of this International Stan-
dard will be designers and implementors of equipment this
This International Standard is related to other International
International Standard contains, in notes or in annexes,
Standards in the set as defined by the Reference Model for
guidance on the implementation of the procedures defined
Open Systems Interconnection (IS0 7498). The Reference
herein.
Model subdivides the area of standardization for interconnec-
tion into a series of layers of specification, each of manageable
It should be noted that, as the number of valid protocol se-
size. It is most closely related to and lies within the field of ap-
quences is very large, it is not possible with current technology
plication of the Session Service Definition (IS0 8326). It also
to verify that an implementation will operate the protocol de-
uses and references the Transport Service Definition
fined in this International Standard correctly under all
(IS0 8û72). whose provisions it assumes in order to accomplish
circumstances. It is possible by means of testing to establish
the aims of the session protocol. The interrelationship of these
confidence that an implementation correctly operates the pro-
International Standards is illustrated in figure 1.
tocol in a representative sample of circumstances. It is,
however, intended that this International Standard can be used
This International Standard specifies a single protocol with a
in circumstances where two implementations fail to com-
common encoding.
municate in order to determine whether one or both have failed
to operate the protocol correctly.
It is intended that the session protocol should be general
enough to cater for the total range of session service users
The variations and options available within this International
without restricting future extensions.
Standard are essential as they enable a session service to be
provided for a wide variety of applications. Thus, a minimally
The protocol is structured so that subsets of protocol can be
conforming implementation will not be suitable for use in all
defined.
possible circumstances. It is important, therefore, to qualify all
references to this International Standard with statements of the
The primary aim of this International Standard is to provide a
options provided or required or with statements of the intended
set of rules. for communication expressed in terms of the pro-
purpose of provision or use.
cedures to be carried out by peer session entities at the time of
communication. These rules for communication are intended
This International Standard contains the following annexes :
to provide a sound basis for development in order to serve a
variety of purposes :
ai annex A - State tables;
a) as a guide for implementors and designers;
b) annex 6 - Relationship to CCllT Recommendation
T.62 encoding;
b) for use in the testing and procurement of equipment;
Session Service Definition
Session Reference to aims
Protocol
Specification Reference to assumptions
Transport Service Definition -
Figure 1 - Relationship between the session protocol and adjacent services
1
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IS0 8327 : 1987 (E)
These procedures are applicable to instances of communication
c) annex C - PGIs and PIS reserved for use by Recom-
between systems which support the Session Layer of the OS1
mendation T.62.
Reference Model and which wish to interconnect in an open
systems environment.
1 Scope and field of application
This International Standard also specifies conformance require-
ments for systems implementing these procedures. It does not
This International Standard specifies
contain tests which can be used to demonstrate this confor-
mance.
a) procedures for a single protocol for the transfer of data
and control information from one session entity to a peer
session entity;
2 References
b) the means of selecting the functional units to be used IS0 7498, Information processing systems - Open Systems
Interconnection - Basic Reference Model.
by the session entities;
IS0 7498fAdd. 3, lnformation processing systems - Open
ci the structure and encoding of the session protocol data
Systems Interconnection - Basic Reference Model - Adden-
units used for the transfer of data and control information.
dum 3: Naming including addressing. 7 1
IS0 8072, Information processing systems - Open Systems
The procedures are defined in terms of
Interconnection - Transport Service Definition.
a) the interactions between peer session entities through IS0 8326, Information processing systems - Open Systems
the exchange of session protocol data units;
Interconnection - Basic connection oriented session service
definition.
b) the interactions between a session entity and the ses-
CClTT Recommendation T.62, Control Procedures for the Tele-
sion service user in the same system through the exchange
tex and Group 4 Facsimile Services.
of session service primitives;
NOTE - CCITT Recommendation T.62 is not essential for the appli-
c) the interactions between a session entity and the trans-
cation of this International Standard, but is included in the list of refe-
port service provider through the exchange of transport ser- rences as it has been referred to, for information, in relation to inter-
CClTT Telematic services (see annex B and Cl.
vice primitives. working with the
1) At present at the stage of draft; publication anticipated in due course.
2
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IS0 8327 : 1987 (El
Section one : General
3.3.2 session-service user (SS-user) : An abstract
3 Definitions
representation of the totality of those entities within a single
NOTE - The definitions contained in this clause make use of abbrevia-
system that make use of the session service.
tions defined in clause 4.
3.1 This International Standard is based on the concepts 3.3.3 transport-service provider (TS-provider) : An
developed in IS0 7498, and makes use of the following terms abstract machine which models the totality of the entities pro-
defined in it :
viding the transport service, as viewed by a session entity.
a) expedited-session-service-data-unit;
3.3.4 local matter : A decision made by a system concerning
b) session-connection;
its behaviour in the Session Layer that is not subject to the re-
c) Session Layer;
quirements of this protocol.
d) session-protocol-data-unit;
0 e) session-service;
3.3.5 initiator : An SPM that initiates a CONNECT SPU.
f) session-service-access-point;
3.3.6 responder : An SPM with whom an initiator wishes to
g) session-service-data-unit;
establish a session connection.
h) Transport Layer;
i) transport-connection;
NOTE - Initiator and responder are defined with respect to a single
session connection.
j) transport-service;
k) transport-service-access-point;
3.3.7 sending SPM : An SPM that sends a given SPDU.
I) concatenation;
m) segmenting;
3.3.8 receiving SPM : An SPM that receives a given SPDU.
n) session selector (defined in IS0 74!38/Add. 3).
3.3.9 owner (of a token) : The SPM to whom a token is
3.2 This International Standard is also based on concepts
assigned.
developed in IS0 8326 and makes use of the following terms
defined in it :
3.3.10 proposed parameter : The value for a parameter pro-
ai token;
posed by an SPM in a CONNECT SPDU or an ACCEPT SPDU
b) calling SS-user;
that it wishes to use on the session connection.
c) called SS-user;
9 d) sending SS-user;
3.3.11 negotiation : The process by which two SPMs agree
a common set of functional units and protocol values and on
on
e) receiving SS-user;
the initial setting of available tokens.
f) requesting SS-user;
g) accepting SS-user;
3.3.12 selected parameter : The value for a parameter that
h) requestor;
has been chosen for use on the session connection.
i) acceptor.
3.3.13 valid SPDU : An SPDU which complies with the
NOTE - The following terms used in this International Standard are
requirements of this International Standard with respect to
used in relation to tokens and are explained in IS0 8326 :
structure and encoding.
a) assigned;
b) not assigned;
3.3.14 invalid SPDU : An SPDU which does not comply
c) available; with the requirements of this International Standard with
respect to structure and encoding.
d) not available.
For the purposes of this International Standard, the
3.3
3.3.15 protocol error: Use of an SPDU that does not
following definitions also apply.
comply with the procedures agreed for the session connection.
3.3.1 Session Protocol Machine (SPM) : An abstract
3.3.16 transparent (data) : SS-user data which is transfer-
machine thatcarriesouttheproceduresspecified in this protocol.
red intact between SPMs and which is unavailable for use by
NOTE - A session entity comprises one or more SPMs.
the SPMs.
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IS0 8327 : 1987 (E)
4.4 Miscellaneous
3.3.17 SPDU identifier (SI) : Heading information that
identifies the SPDU concerned.
Session Protocol Machine (see 3.3.1)
SPM
SS session-service
3.3.18 length indicator (LI) : An indicator that represents
SSAP session-service-access-point
the length of an associated parameter field.
TSAP transport-service-access-point
3.3.19 parameter field : A group of one or more octets used
4.5 Local variables
to represent a particular set of information.
Vact See 5.8.1
3.3.20 parameter identifier (PI) : An identifier, defined in
Vnextact See 5.8.2
this International Standard, that indicates the type of
ViA) See 5.8.3
information contained in its associated parameter field.
V(M) See 5.8.4
V(R) See 5.8.5
vsc See 5.8.6
3.3.21 PI unit : An element of an SPDU that contains a PI
field together with its associated LI field and parameter field.
5 Overview of the session protocol
3.3.22 parameter group identifier (PGI) : An identifier,
defined in this International Standard, that indicates the type of
5.1 Model of the Session Layer
information contained in its associated parameter field. The
associated parameter field may consist of a set of PI units.
The SPM (see the note) within the Session Layer
communicates with the SS-user through an SSAP by means of
3.3.23 PGI unit : An element of an SPDU that contains a PGI
the service primitives as defined by the session service
LI field and parameter field.
field together with its associated
definition (IS0 8326). Service primitives will cause or be the
result of session protocol data unit exchanges between the
peer SPMs using a transport connection. These protocol
3.3.24 parameter value (PV) : Information that represents
exchanges are effected using the services of the Transport
the value of the parameter identified by either a PI or PGI.
Layer as defined by the transport service definition (IS0 8072)
through two TSAPs.
3.3.25 local variable : A local variable within the SPM which
is used as a means of clarifying the effects of certain actions
Session connection endpoints are identified in end systems by
and clarifying the conditions under which certain actions are
so that the
an internal, implementation dependent, mechanism
permitted.
SS-user and the SPM can refer to each session connection.
The model of the Session Layer is illustrated in figure 2.
4 Symbols and abbreviations
NOTE - A session entity comprises one or more SPMs.
4.1 Data units
5.2 Services provided by the Session Layer
SPDU session-protocol-data-unit
SSDU session-service-data-unit
The protocol specified in this lnternhonal Standard supports
TSDU transport-service-data-unit
the session service defined in IS0 8326. Information is
transferred to and from the SS-user using the session service
primitives listed in table 1. Table 1 also defines the SPDUs
4.2 SPDU fields
associated with each of the service primitives.
SI SPDU identifier (see 3.3.17)
LI length indicator (see 3.3.18)
5.3 Services assumed from the Transport Layer
PI parameter identifier (see 3.3.20)
parameter group identifier (see 3.3.22)
PGI
The protocol specified in this International Standard assumes
PV parameter value (see 3.3.24)
the use of the connection-oriented transport service defined in
IS0 8072.
4.3 Timer variables
Information is transferred to and from the TS-provider in the
transport service primitives listed in table 2.
TIM Disconnection and abort timer
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IS0 8327 : 1987 (E)
( SSAP )
( SSAP )
Session Protocol Sessior7 ,Protocol
Machine
Machine
I
I l
TSAP
( TSAP ) ( 1 )
Figure 2 - Model of the Session Layer
5
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IS0 8327 : 1987 (E)
Table 1 - Session service primitives
Associated SPDUs
Service Primitives
Session CONNECT SPDU
S-CONNECT request
connection
CONNECT SPDU
S-CONNECT indication
S-CONNECT (accept) response ACCEPT SPDU
ACCEPT SPDU
S-CONNECT (accept) confirm
REFUSE SPDU
S-CONNECT (reject) response
REFUSE SPDU
S-CONNECT (reject) confirm
DATA TRANSFER SPDU
Normal S-DATA request
S-DATA indication DATA TRANSFER SPDU
transfer
Expedited S-EXPEDITED-DATA request EXPEDITED DATA SPDU
S-EXPEDITED-DATA indication EXPEDITED DATA SPDU
transfer
S-TYPED-DATA request TYPED DATA SPDU
S-TYPED-DATA indication TYPED DATA SPDU
CAPABILITY DATA SPDU
Capability S-CAPABILITY-DATA request
CAPABILITY DATA SPDU
S-CAPABILITY-DATA indication
exchange
CAPABILITY DATA ACK SPDU
S-CAPABILITY-DATA response
CAPABILITY DATA ACK SPDU
S-CAPABILITY-DATA confirm
GIVE TOKENS SPDU
S-TOKEN-GIVE request
tokens
GIVE TOKENS SPDU
S-TOKEN-GIVE indication
PLEASE TOKENS SPDU
Please S-TOKEN-PLEASE request
tokens
PLEASE TOKENS SPDU
S-TOKEN-PLEASE indication
GIVE TOKENS CONFIRM SPDU
Give S-CONTROL-GIVE request
t control
GIVE TOKENS CONFIRM SPDU
S-CONTROL-GIVE indication
MINOR SYNC POINT SPDU
Minor
S-SYNC-MINOR request
synchron-
MINOR SYNC POINT SPDU
S-SYNC-MINOR indication
ization
point MINOR SYNC ACK SPDU
S-SYNC-MINOR response
MINOR SYNC ACK SPDU
S-SYNC-MINOR confirm
MAJOR SYNC SPDU
S-SYNC-MAJOR request
synchron-
MAJOR SYNC POINT SPDU
S-SYNC-MAJOR indication
nization
point MAJOR SYNC ACK SPDU
S-SYNC-MAJOR response
MAJOR SYNC ACK SPDU
S-SYNC-MAJOR confirm
RESYNCHRONIZE SPDU
S-RESYNCHRONIZE request
ization
RESYNCHRONIZE SPDU
S-RESYNCHRONIZE indication
RESYNCHRONIZE ACK SPDU
S-RESYNCHRONIZE response
RESYNCHRONIZE ACK SPDU
S-RESYNCHRONIZE confirm
EXCEPTION REPORT SPDU
P;Exception
S-P-EXCEPTION-REPORT indication
report
EXCEPTION DATA SPDU
U-Exception S-U-EXCEPTION-REPORT request
reporting
EXCEPTION DATA SPDU
S-U-EXCEPTION-REPORT indication
ACTIVITY START SPDU
Activity S-ACTIVITY-START request
ACTIVITY START SPDU
S-ACTIVITY-START indication
6
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IS0 8327 : 1987 (E)
Table 'I (concluded
Primitives Associated SPDUs
Service
Activity S-ACTIVITY-RESUME request ACTIVITY RESUME SPDU
resume
S-ACTIVITY-RESUME indication ACTIVITY RESUME SPDU
Activity S-ACTIVITY-INTERRUPT request ACTIVITY INTERRUPT SPDU
interrupt
S-ACTIVITY-INTERRUPT indication ACTIVITY INTERRUPT SPDU
ACTIVITY INTERRUPT ACK SPDU
S-ACTIVITY-INTERRUPT response
S-ACTIVITY-INTERRUPT confirm ACTIVITY INTERRUPT ACK SPDU
Activity ACTIVITY DISCARD SPDU
S-ACTIVITY-DISCARD request
discard
S-ACTIVITY-DISCARD indication ACTIVITY DISCARD SPDU
S-ACTIVITY-DISCARD response ACTIVITY DISCARD ACK SPDU
S-ACTIVITY-DISCARD confirm ACTIVITY DISCARD ACK SPDU
Activity S-ACTIVITY-END request ACTIVITY END SPDU
end
S-ACTIVITY-END indi
...
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