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.\" Troff code generated by TPS Convert from ITU Original Files
.\" Not Copyright (~c) 1991
.\"
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.EN
.nr LL 40.5P
.nr ll 40.5P
.nr HM 3P
.nr FM 6P
.nr PO 4P
.nr PD 9p
.po 4P
.rs
\v'|.5i'
.sp 1P
.ce 1000
\v'12P'
\s12FASCICLE\ VIII.6
\v'4P'
.RT
.ce 0
.sp 1P
.ce 1000
\fBRecommendations X.300 to X.370\fR \v'2P'
.EF '% \ \ \ ^''
.OF ''' \ \ \ ^ %'
.ce 0
.sp 1P
.ce 1000
\fBDATA\ COMMUNICATION\ NETWORKS:\fR
.ce 0
.ce 1000
\fR \fBINTERWORKING\ BETWEEN\ NETWORKS,\fR
.ce 0
.ce 1000
\fBMOBILE\ DATA\ TRANSMISSION SYSTEMS,\fR
.ce 0
.sp 1P
.ce 1000
\fBINTERNETWORK MANAGEMENT\fR \v'2P'
.ce 0
.sp 1P
.LP
.rs
.sp 27P
.LP
Blanc
.bp
.LP
.EF '% \ \ \ ^''
.OF ''' \ \ \ ^ %'
.LP
.bp
.LP
\fBMONTAGE:\fR PAGE 2 = PAGE BLANCHE
.sp 1P
.RT
.LP
.bp
.sp 1P
.ce 1000
\v'3P'
SECTION\ 1
.ce 0
.sp 1P
.ce 1000
\fBINTERWORKING\ BETWEEN\ NETWORKS\fR
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation\ X.300\fR
.RT
.sp 2P
.ce 1000
\fBGENERAL\ PRINCIPLES\ FOR\ INTERWORKING\ BETWEEN\ PUBLIC\ NETWORKS,\fR \|
\fBAND\ BETWEEN\ PUBLIC\fR
.EF '% Fascicle\ VIII.6\ \(em\ Rec.\ X.300''
.OF '''Fascicle\ VIII.6\ \(em\ Rec.\ X.300 %'
.ce 0
.ce 1000
\fBNETWORKS\ AND\ OTHER\ NETWORKS\ FOR\ THE\ PROVISION\fR
.ce 0
.sp 1P
.ce 1000
\fBOF\ DATA\ TRANSMISION\ SERVICES\fR
.ce 0
.sp 1P
.ce 1000
\fI(Former Recommendation X.87, Geneva, 1980;\fR
.sp 9p
.RT
.ce 0
.sp 1P
.ce 1000
\fIamended at Malaga\(hyTorremolinos, 1984 and Melbourne, 1988)\fR
.ce 0
.sp 1P
.LP
The\ CCITT,
.sp 1P
.RT
.sp 1P
.LP
\fIconsidering\fR
.sp 9p
.RT
.PP
(a)
that Recommendation X.1 defines the international user classes of service
in public data networks (PDNs) and integrated services
digital network (ISDN);
.PP
(b)
that Recommendation X.2 defines the international user services and facilities
in PDN and ISND;
.PP
(c)
that Recommendation X.10 defines the different
categories of access of data terminal equipments (DTEs) to the different
data transmission services provided by PDNs and ISDN;
.PP
(d)
that Recommendation X.96 defines call progress signals including those
used in conjunction with international user facilities;
.PP
(e)
that Recommendations X.20, X.20\|\fIbis\fR ,
X.21, X.21\|\fIbis\fR , X.25, X.28, X.29, X.30, X.31 and\ X.32 already
specify the
detailed procedures applicable to different types of DTE/DCE interfaces
on PDNs and ISDNs;
.PP
(
f
)
that Recommendations X.61, X.70, X.71 and
X.75 already specify the detailed procedures applicable to call control
between two PDNs on the same type;
.PP
(g)
that PDNs and ISDNs are used to support
telecommunication services and CCITT defined services (e.g.\ Telematic
services);
.PP
(h)
that Recommendation X.200 specifies the reference model of open system
interconnection (OSI) for CCITT Applications;
.PP
(i)
that Recommandation X.213 defines the connection\(hymode
network service definition of OSI for CCITT applications;
.PP
(j)
that Recommendation X.301 gives the description of the general arrangements
for call control within a subnetwork and between
subnetworks for the provision of data transmission services;
.PP
(k)
that Recommendation X.302 describes the general
arrangements for call control within a subnetwork and between subnetworks
for the provision of data transmission services;
.PP
(l)
that Recommendation X.305 describes the functionalities of subnetworks
relating to the support of the OSI connection\(hymode network
service;
.bp
.PP
(m)
that interworking with common chanel signalling network (CCSN) needs to
be considered, in view of the requirements for transferring
operational information between Administrations;
.PP
(n)
the need that DTEs can communicate through different
networks, and through different interworking conditions between networks;
.PP
(o)
the need for general principles and arrangements for
interworking between public networks and between public networks and other
public networks for the provision of data transmission services;
.PP
(p)
the need for the provision of data transmission
services, in particular:
.LP
\(em
for certain user facilities and network utilities for
communication through the national networks between the internationally
defined data terminal equipment interface protocols and international inter\(hyexchange
control and signalling procedures;
.LP
\(em
for certain internationally defined network utilities for
international operation of public networks;
.LP
\(em
for compatibility and uniformity in the principles for
realization of international user facilities and network utilities in the
public networks;
.sp 1P
.LP
\fIunanimously recommends\fR
.sp 9p
.RT
.PP
that general principles for interworking between public networks and between
public networks and other networks, and that the necessary
elements:
.LP
\(em
for realization of interworking between different networks
providing data transmission services, and
.LP
\(em
for realization of international user facilities and network utilities
for data transmission services,
.LP
be in accordance with the principles and procedures specified in this
Recommendation.
.sp 1P
.ce 1000
CONTENTS
.ce 0
.sp 1P
.LP
0
\fIIntroduction\fR
.sp 1P
.RT
.sp 1P
.LP
1
\fIScope and field of application\fR
.sp 9p
.RT
.sp 1P
.LP
2
\fIReferences\fR
.sp 9p
.RT
.sp 1P
.LP
3
\fIDefinitions\fR
.sp 9p
.RT
.sp 1P
.LP
3.1
Terminology defined in other Recommendations
.sp 9p
.RT
.LP
3.2
Terminology defined in this Recommendation
.LP
3.3
Graphical conventions
.sp 1P
.LP
4
\fIAbreviations\fR
.sp 9p
.RT
.sp 2P
.LP
5
\fIReal networks to be interconnected and, data transmission services\fR
\fIto be offered\fR
.sp 1P
.RT
.sp 1P
.LP
5.1
Packet switched public data network (PSPDN)
.sp 9p
.RT
.LP
5.2
Circuit switched public data network (CSPDN)
.LP
5.3
Integrated services digital network (ISDN)
.LP
5.4
Public switched telephone network (PSTN)
.bp
.LP
5.5
Common channel signalling network (CCSN)
.LP
5.6
Public mobile systems
.LP
5.7
Private networks
.sp 2P
.LP
6
\fIPrinciples for interworking involving transmission capability only\fR
.sp 1P
.RT
.sp 1P
.LP
6.1
Composition and decomposition of subnetworks
.sp 9p
.RT
.LP
6.2
Categories of interworking
.LP
6.3
Categorization of subnetworks with respect to the support of the
OSI NS
.LP
6.4
Relationships with respect to management
.LP
6.5
Basic principles in relation with service indication parameters
.sp 2P
.LP
7
\fIPrinciples for interworking involving both transmission capability\fR
\fIand communication capability\fR
.sp 1P
.RT
.sp 1P
.LP
7.1
Composition and decomposition of application relay systems
.sp 9p
.RT
.LP
7.2
Categories of interworking
.LP
7.3
Identification of application relay system types
.LP
7.4
Relation between application IWF, real networks and application
relay system types
.LP
7.5
Interconnection of application relay system types
.LP
7.6
Use of application relay system types
.LP
7.7
Relationships with respect to management
.LP
7.8
Relationships with Reference Model of OSI for CCITT applications
.LP
7.9
Basic principles in relation with service indication parameters
.sp 2P
.LP
8
\fIDescription of the different interworking conditions\fR
.sp 1P
.RT
.sp 1P
.LP
8.1
General
.sp 9p
.RT
.LP
8.3
Interworking via a non\(hyOSI Adapter between PSTN and PSPDN
.LP
8.3
Interworking involving ISDN for the provision of data transmission services
.sp 1P
.LP
\fIAnnex\ A\fR \(em
\fIBasic Categories of Subnetworks\fR
.sp 9p
.RT
.sp 1P
.LP
\fIAnnex\ B\fR \(em
\fIExamples of subnetwork types\fR
.sp 9p
.RT
.sp 2P
.LP
\fB0\fR \fBIntroduction\fR
.sp 1P
.RT
.PP
0.1
The rapid evolution of data transmission services has resulted in a large
number of international standards in this field. The increasing
complexity of the totality of these standards creates a need to rationalize
common aspects in order to achieve a coherent relationship between these
standards.
.sp 9p
.RT
.PP
0.2
Data transmission services and user facilities may be provided
by different types of public networks such as, PDNs and integrated services
digital networks (ISDN) (see also\ I.500 and\ I.510). As a result, there
may be a demand to interconnect these networks in order for a DTE on one
network to
communicate in a uniform way with a DTE on the same network, or with a
DTE on another network of the same type, or with a DTE on a network of
another type.
.PP
0.3
The internetwork signalling between the various types of networks can be
of the type defined by Recommendations such as,\ X.70, X.71, X.75, or of
the common channel signalling type such as, X.61.
.PP
In particular, at an internetwork signalling interface, network
utilities may be exchanged between the networks involved. These network
utilities may be handled by different types of networks.
.bp
.PP
0.4
In addition, as a part of the scope of Recommendation\ X.200
(Reference Model of Open Systems Interconnection for CCITT Applications)
is to enable different users to communicate with each other by encouraging
the
implementation of compatible communication features, the use of this Reference
Model is expected to be encouraged in future user terminal designs.
.PP
0.5
As defined by this Reference Model, one of the major functions of the network
layer is to establish a network\(hyconnection between network\(hyservice
users (within end\(hysystems). This may involve the concatenation of dissimilar
networks.
.PP
Therefore, the arrangemenets and procedures for internetwork
signalling between PDNs and other public networks should provide the user
with the capability to operate data transmission services, telematic services
and
the OSI connection\(hymode Network Service over the connections derived over
either one network, or over concatenated networks.
.PP
\fINote\fR \ \(em\ This does not imply that any individual public network
is required to implement all the mechanisms related to the OSI connection\(hymode
Network Service.
.RT
.PP
0.6
This Recommendation is one of a family of interworking
Recommendations. Figure\ 0\(hy1/X.300 gives a summary of the relevant interworking
Recommendations, which are grouped under three main categories:
.LP
a)
General aspects of interworking,
.LP
b)
Description of each interworking case,
.LP
c)
Description of internetwork signalling interfaces.
.LP
.rs
.sp 30P
.ad r
\fBFigure 0\(hy1/X.300, p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
\fB1\fR \fBScope and field of application\fR
.sp 1P
.RT
.PP
1.1
Interworking between more than two networks is included in the scope of
this Recommendation.
.sp 9p
.RT
.PP
1.2
The scope of this Recommendation is:
.LP
\(em
to define principles and detailed arrangements for the
interworking of different networks in order to provide a data transmission
service;
.LP
\(em
to specify, in a general network context, the necessary
interaction between elements of user interfaces, interexchange signalling
systems and other network functions; for the support of data transmission
services, telematic services and the OSI connection\(hymode network service
where appropriate;
.LP
\fINote\fR \ \(em\ The support for OSI connectionless\(hymode network
service as defined in ISO\ 8348/Ad\ 1 is for further study.
.LP
\(em
to define the principles for realization of international
user facilities and network utilities for data transmission services.
.sp 2P
.LP
\fB2\fR \fBReferences\fR
.sp 1P
.RT
.sp 1P
.LP
I.112
Vocabulary of terms for ISDNs,
.sp 9p
.RT
.LP
I.210
Principles of Telecommunication services supported by an ISDN,
.LP
I.230\ Series
Bearer Services supported by an ISDN,
.LP
I.240\ Series
Teleservices supported by an ISDN,
.LP
I.250\ Series
Definitions and description of Supplementary Services,
.LP
I.340
ISDN connection types,
.LP
I.411
ISDN user\(hynetwork interfaces \(em Reference Configurations,
.LP
I.420
Basic user\(hynetwork interface,
.LP
I.421
Primatry rate user\(hynetwork interface,
.LP
I.500
General structure of the ISDN interworking Recommendations
.LP
I.510
Definitions and general principles for ISDN interworking,
.LP
Q.700\ Series
Specifications of Signalling System No.\ 7,
.LP
X.1
International user classes of service in public data networks (PDNs)
and ISDNs,
.LP
X.2
International data transmission services and optional user facilities in PDNs,
.LP
X.10
Categories of access for data terminal equipment to public data
transmission services,
.LP
X.20
Interface between data terminal equipment (DTE) and data
circuit\(hyterminating equipment (DCE) for start\(hystop transmission services
on
PDNs,
.LP
X.20\|\fIbis\fR Use on PDNs of DTE which is designed for interfacing to
asynchronous duplex V\(hySeries modems,
.LP
X.21
Interface between DTE and DCE for synchronous operation on PDNs,
.LP
X.21\|\fIbis\fR Use on PDNs of DTE which is designed for interfacing to
synchronous V\(hySeries modems,
.LP
X.22
Multiplex DTE/DCE interface for user classes 3\(hy6,
.LP
X.25
Interface between DTE and DCE for terminals operating in the
packet\(hymode on PDNs and connected to PDNs by dedicated circuit,
.LP
X.28
DTE/DCE Interface for a start\(hystop mode DTE accessing the packet
assembly/disassembly (PAD) facility in a PDN situated in the same country,
.bp
.LP
X.29
Procedures for the exchange of control information and user data
between PAD facility and a packet\(hymode DTE or another PAD,
.LP
X.30/I.461
Support of X.21, X.21\|\fIbis\fR and X.20\|\fIbis\fR based DTEs by an
ISDN,
.LP
X.31/I.462
Support of packet\(hymode terminal equipment by an ISDN,
.LP
X.32
Interface between DTE and DCE for terminals operating in the
packet\(hymode and accessing a PSPDN through a PSTN or an ISDN or a CSPDN.
.LP
X.60
Common channel signalling for circuit switched data applications,
.LP
X.61
Signalling System No.\ 7 \(em Data user part,
.LP
X.70
Terminal and transit control signalling system for start\(hystop services
on international circuits between anisochronous data networks,
.LP
X.71
Decentralized terminal and transit control signalling system on
international circuit between synchronous data networks,
.LP
X.75
Packet switched signalling system between public networks providing
data transmission services,
.LP
X.80
Interworking of interexchange signalling systems for a circuit switched
data services,
.LP
X.81
Interworking between an ISDN and a CSPDN,
.LP
X.82
Detailed arrangements for interworking between CSPDNs and PSPDNs
based on Recommendation\ T.70.
.LP
X.96
Call progress signals in PDNs,
.LP
X.180
Administrative arrangements for international closed user groups
(CUGs),
.LP
X.181
Administrative arrangements for the provision of international
permanent virtual circuit service,
.LP
X.200
Reference model for Open Systems Interconnection (OSI) for CCITT
applications,
.LP
X.210
Open systems interconnection (OSI) \(em layer service conventions,
.LP
X.213
Network service definition for OSI for CCITT applications,
.LP
X.301
Description of the general arrangements for call control within a
subnetwork and between subnetworks for the provision of data transmission
services,
.LP
X.302
Description of the general arrangements for internal network utilities
within a subnetwork and between subnetworks for the provision of data
transmission services,
.LP
X.305
Functionalities of subnetworks relating to the support of the OSI
connection\(hymode network service,
.LP
X.320
General arrangements for interworking between ISDNs for the provision
of data transmission services,
.LP
X.321(I.540)
General arrangements for interworking between CSPDNs and ISDNs for the
provision of data transmission services,
.LP
X.322
General arrangements for interworking between PSPDNs and CSPDNs for
the provision of data transmission services,
.LP
X.323
General arrangements for interworking between PSPDNs,
.LP
X.324
General arrangements for interworking between PSPDNs and public mobile
systems for the provision of data transmission services,
.LP
X.325(I.550)
General arrangements for interworking between PSPDNs and ISDNs for the
provision of data transmission services,
.bp
.LP
X.326
General arrangements for interworking between PSPDNs and CCSN for the
provision of data transmission services,
.LP
X.327
General arrangements for interworking between PSPDNs and private
networks for the provision of data transmission services,
.LP
X.350
General requirements for data transmission in the international public
mobile satellite systems,
.LP
X.351
Special requirements to be met for packet assembly/dissassembly (PAD)
facilities located at or in association with coast earth stations in the
public mobile satellite service,
.LP
X.352
Interworking between PSPDNs and the public mobile satellite data
transmission system,
.LP
X.370
Arrangements for the transfer of internetwork management information.
.sp 2P
.LP
\fB3\fR \fBDefinitions\fR
.sp 1P
.RT
.sp 1P
.LP
3.1
\fITerminology defined in other Recommendations\fR
.sp 9p
.RT
.PP
This Recommendation makes use of the following concepts and terms defined
in other Recommendations.
.RT
.LP
\fIConcept or term\fR \fIRecommendation\fR
.LP
a)
Bearer service (see also \(sc\ 3.2.8 data transmission service)
I.112 &\ I.210
.LP
b)
Exchange
I.112
.LP
c)
Integrated services digital network
I.112
.LP
d)
Maritime satellite data transmission system
X.350
.LP
e)
OSI network layer
X.200
.LP
f
)
OSI network service
X.200
.LP
g)
Packet assembly/disassembly (Note)
.LP
h)
Public data network (Note)
.LP
i)
Public land mobile network
Q.70
.LP
j)
Service provider
X.210
.LP
k)
Service user
X.210
.LP
l)
Telecommunication service (see also \(sc\ 3.2.5 CCITT Service)
I.112
.LP
m)
Teleservice
I.112
.LP
n)
Terminal adaptator
I.411
.PP
\fINote\fR \ \(em\ this term is contained in the Blue Book (Volume\ I.3).
.sp 1P
.LP
3.2
\fITerminology defined in this Recommendation\fR
.sp 9p
.RT
.PP
This section provides concepts and definitions additional to those defined
in other Recommendations. Some concepts and terms provided in this
section are defined by using Figures\ 3\(hy1/X/300 and\ 3\(hy2/X.300, which
form part of their definition (For graphical conventions see \(sc\ 3.3).
.RT
.sp 1P
.LP
3.2.1
\fBapplication\(hyrelay system\fR
.sp 9p
.RT
.PP
The functional abstraction of an application interworking function (IWF).
.RT
.sp 1P
.LP
3.2.2
\fBapplication interworking function\fR
.sp 9p
.RT
.PP
A collection of processes that intervenes in an information flow also associated
with applications, relating protocol(s) that access this
collection to protocol(s) that exit this collection.
.PP
An IWF, that also acts upon information related to that
application.
.RT
.sp 1P
.LP
3.2.3
\fIApplication\(hyrelay service\fR
.sp 9p
.RT
.PP
(For further study.)
.bp
.RT
.LP
.rs
.sp 47P
.ad r
\fBFigure 3\(hy1/X.300, p. 2\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 47P
.ad r
\fBFigure 3\(hy2/X.300, p. 3\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
3.2.4
\fIApplication\(hyrelay functionality\fR
.sp 9p
.RT
.PP
(For further study.)
.RT
.sp 1P
.LP
3.2.5
\fBCCITT service\fR
.sp 9p
.RT
.LP
(\fINote\fR \ \(em\ This concept is assumed to be equivalent to
telecommunication service).
.PP
Services defined in CCITT Recommendations, to be marketed to the
users by Administrations. Different types of CCITT services may be marketed
as follows:
.RT
.LP
a)
Data transmission services, as defined in Recommendation\ X.1 and X.2
(i.e.\ circuit switched and packet switched data transmission services
and leased circuit services);
.LP
b)
Services involving additional functions, on top of those
functions providing transmission capability (e.g.\ PAD, Telex, Teletex).
.LP
On top of data transmission service, users may establish a privately defined
application.
.LP
.rs
.sp 17P
.ad r
\fBFigure 3\(hy3/X.300 p.\fR
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
3.2.6
\fBcommunication capability\fR
.sp 9p
.RT
.PP
A communication capability consists of the means of communication between
systems, related to functions above transmission capability. A
communication capability may be defined by CCITT, it may also be privately
defined by users themselves.
.RT
.sp 1P
.LP
3.2.7
\fBconvergence protocol\fR
.sp 9p
.RT
.PP
A protocol that is used on top of a subnetwork service
(transparent for the related subnetwork), in order to construct another
subnetwork service. This protocol may be active during all, or only some
of the call related to the constructed subnetwork service.
.RT
.sp 1P
.LP
3.2.8
\fBdata transmission service\fR
.sp 9p
.RT
.PP
Data transmission service is that service offered by an
Administration, RPOA or any private network operator to satify a
telecommunication requirement and is composed of technical attributes as
seen by the customer and other attributes associated with the service provision,
e.g.\ operational. Use of the technical attributes requires mechanisms
to access subnetworks as defined in Recommendation\ X.1 (circuit switched
service, packet switched service and leased circuit service) and I.230\(hySeries
Recommendations and Recommendation\ X.10, as far as the prupose of transparent
transmission is concerned.
.PP
\fINote\fR \ \(em\ this concept is assumed to be equivalent to the bearer
service.
.bp
.RT
.sp 1P
.LP
3.2.9
\fBend system\fR
.sp 9p
.RT
.PP
The functional abstraction of a real end system.
.RT
.sp 1P
.LP
3.2.10
\fBinterworking by call control mapping\fR
.sp 9p
.RT
.PP
Technique of interworking where all call control (including
addresing) information carried by the protocol(s) used for switching by
the one subnetwork is mapped into the call control (including address)
information
carried by the protocol(s) used for switching by the other subnetwork.
.RT
.sp 1P
.LP
3.2.11
\fBinterworking by port access\fR
.sp 9p
.RT
.PP
Technique of interworking where all call control (including
addressing) information carried by the protocol(s) used for switching by the
one subnetwork is used to select/address the interworking point. Subsequently,
a convergence protocol is used over this subnetwork carrying all call control
(including addressing) information that will be mapped into the addressing
information carried by the protocols used for switching by the other
subnetwork.
.RT
.sp 2P
.LP
3.2.12
\fBinterworking function\fR
.sp 1P
.RT
.sp 1P
.LP
3.2.12.1\ \ The interworking functions (IWFs) considered in this
Recommendation are functional entities involved for the establishment of
a call between two end systems, whenever two networks are involved between
those two end systems.
.sp 9p
.RT
.PP
\fINote\ 1\fR \ \(em\ The description of IWFs in examples given in
furthersections of this Recommendation does not make any assumption on the
implementation of such functions: either within one network involved, or
as a separate piece of equipment. Also several IWFs between two networks
may be
combined into one single piece of equipment.
.PP
\fINote\ 2\fR \ \(em\ An IWF may be involved in cases where two dissimilar
networks are involved, or in cases where two networks of the same type are
involved.
.PP
\fINote\ 3\fR \ \(em\ An IWF only acts for the transparent transfer of
information (independent of any application).
.PP
\fINote\ 4\fR \ \(em\ An access unit (AU), packet handler (PH) or ISDN
terminal adapter may also be considered an IWF.
.RT
.LP
3.2.12.2\ \ In some cases of interconnection between two networks, several
IWFs may be involved. However, for a given communication between two end
systems,
only one of those IWFs is involved.
.LP
3.2.12.3\ \ Figure 3\(hy4/X.300 illustrates an example of interworking
between two networks by means of IWFs. There may be other cases, where
more than two
networks would be involved, possibly with more\ IWFs.
.LP
.rs
.sp 11P
.ad r
\fBFigure 3\(hy4/X.300 p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
3.2.13
\fBnetwork\fR (Expansion of definition in Recommendation\ I.112)
.sp 9p
.RT
.PP
A set of nodes and links that provide connections between two or
more defined port to facilitate telecommunication between them. In particular,
a network can for one particular instance of communication:
.RT
.LP
a)
act for transparent transfer of information only (independent of any
application), or
.LP
b)
also act upon the information related to the application
itself.
.sp 1P
.LP
3.2.14
\fBnetwork\fR *
.sp 9p
.RT
.PP
Any combination ofswitch(es) or exchange(s), and/or networks,
and/or IWFs.
.RT
.sp 1P
.LP
3.2.15
\fBreal application relay system\fR
.sp 9p
.RT
.PP
Any combination of networks*, networks, and application IWFs where at least
one network and/or application IWF also acts upon the information
related to that application.
.RT
.sp 1P
.LP
3.2.16
\fBreal end system\fR
.sp 9p
.RT
.PP
A DTE or TE having the capability to communicate, and serving as origination
or destination of an instance of communication related to its
application(s), and which is not an intermediate system or subnetwork.
.RT
.sp 1P
.LP
3.2.17
\fBsubnetwork\fR
.sp 9p
.RT
.PP
A functional abstraction of a set of one or more intermediate
systems which provide relaying and through which end systems may establish
network connection, only related to the lower three layers of the OSI model
(see Recommendation\ X.200).
.RT
.sp 1P
.LP
3.2.18
\fBsubnetwork functionality\fR
.sp 9p
.RT
.PP
Functionalities residing within a subnetwork are related to the
ways the subnetwork supports connections through it. These functionalities
may differ in each type of subnetwork depending on the call control and
data
transfer phases.
.RT
.sp 1P
.LP
3.2.19
\fBsubnetwork service\fR
.sp 9p
.RT
.PP
A service supported by the protocols used in a subnetwork for an instance
of communication. This service is the same at the service access
points.
.RT
.sp 1P
.LP
3.2.20
\fBsubnetwork type\fR
.sp 9p
.RT
.PP
A subnetwork with a functionality defined on the capability to
support the OSI connection\(hymode network service. The term is only valid
in this specific context.
.RT
.sp 1P
.LP
3.2.21
\fBtransmission capability\fR
.sp 9p
.RT
.PP
Transmission capability consists of all the necessary mechanisms
required through a subnetwork (or subnetworks interworking) for the transparent
transfer of data between users' equipment or application intermediate system,
including the related mechanism within the end systems. This includes all
mechanism required to access subnetworks, as defined in the I.230\(hySeries
Recommendations and Recommendation\ X.10 as far as the purpose of transparent
transmission of information is concerned. It may also include special
management functions; such functions are for further study.
.PP
\fINote\fR \ \(em\ It is understood that some optional user
facilities/supplementary services as defined in Recommendation\ X.2 and the
I.230\(hySeries related to transmission capability only, while others also
relate to communication capability. The exact lists in each category is
not subject of this Recommendation.
.RT
.sp 1P
.LP
3.2.22
\fBtelecommunication capability\fR
.sp 9p
.RT
.PP
The combined functionality of the communication capability and the transmission
capability.
.RT
.PP
3.2.23
Table 3\(hy1/X.300 provides a relationship to some of the terms
defined above.
.bp
.ce
\fBH.T. [T1.300]\fR
.ce
TABLE 3\(hy1/X.300
.ce
\fBRelative relationship of real and abstract objects used in this
.ce
Recommendation\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(84p) | cw(84p) .
T{
Objects related to transmission
Capability only for one instance
of communication
T} T{
Objects related to communication
Capability only for one instance
of communication
T}
.T&
lw(60p) | lw(84p) | lw(84p) .
Real world objects T{
\(bu
\ \|Network
\(bu
\ \|Interworking Function
(IWF)
T} T{
\(bu
\ \|Network
\(bu
\ \|Application IWF
\(bu
\ \|Real application relay system
T}
_
.T&
lw(60p) | lw(84p) | lw(84p) .
Abstract elements \(bu \ \|Subnetwork T{
\(bu
\ \|Application relay system
T}
_
.TE
.nr PS 9
.RT
.ad r
\fBTABLE 3\(hy1/X.300 [T1.300] p.\fR
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
3.3
\fIGraphical conventions\fR
.sp 9p
.RT
.PP
This section defines the relationship between some terms used in
this Recommendation and their graphical representation as used in this
Recommendation. In addition, it defines the relationship between some terms
related to real world objects and the terms related to their abstraction
for a particular instance of communication. Tables\ 3\(hy2/X.300 and 3\(hy3/X.300
summarize the symbols and objects covered in this Recommendation.
.RT
.PP
The graphical indication of a subnetwork functionality corresponds to the
particular subnetwork types as allocated in this Recommendation. The
graphical indication will be expressed in Roman numbers as follows (using
Backus\(hyNaur Form):
.LP
<indication> ::= <subnetwork type I>|<subnetwork type II>|<subnetwork
type III>
.LP
<subnetwork type I>\ \ \ ::= <I>
.LP
<subnetwork type II>\ \ ::= <II>
.LP
<subnetwork type III>\ ::= <III>
.sp 2P
.LP
\fB4\fR \fBAbbreviations\fR \v'3p'
.sp 1P
.RT
.LP
AU
access unit
.LP
CCSN
Common channel signalling network (SS No.\ 7)
.LP
SS\ No.\ 7
Signalling system No.\ 7
.LP
CS
Circuit switched
.LP
CSPDN
Circuit switched public data network
.LP
DCE
Data circuit\(hyterminating equipment
.LP
DSE
Digital switching exchange
.LP
DTE
Data terminal equipment
.LP
IDSE
International data switching exchange
.LP
ISDN
Integrated services digital network
.LP
IWF
Interworking function
.LP
NDSE
National data switching exchange
.LP
NS
Network service
.LP
OSI
Open systems interconnection
.LP
PAD
Packet assembler/dissembler
.LP
PDN
Public data network
.LP
PLMN
Public land mobile network
.LP
PS
Packet Switched
.LP
PSPDN
Packet switched public data network
.LP
PSTN
Public switched telephone network
.LP
PM
Packet handler
.LP
TA
Terminal adaptor
.LP
TE
Terminal equipment
.bp
.LP
.rs
.sp 47P
.ad r
\fBTableau 3\(hy2/X.300, p. 7\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 47P
.ad r
\fBTableau 3\(hy3/X.300, p. 8\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
\fB5\fR \fBNetworks to be interconnected, and data transmission services\fR
\fBto be offered\fR
.sp 1P
.RT
.PP
This section lists the networks considered in this Recommendation for provision
of Data Transmission Services, and indicates where appropriate, the extent
to which those networks provide support for the full capability of the
OSI connection\(hymode network service at the DTE/DCE interface.
.PP
International data transmission services may be provided through the interworking
of different types of networks, as follows:
.RT
.LP
\(em
Public data networks (PDNs)
.LP
\(em
Integrated services digital network (ISDN)
.LP
\(em
Public switched telephone network (PSTN)
.LP
\(em
Mobile networks or systems
.LP
\(em
Private networks.
.PP
\fINote\ 1\fR \ \(em\ Other services, not related to data transmission
services, may also be provided by interworking involving PDNs. In particular,
the requirements for a PDN when interworking with the public telex network
in respect of CCITT telex service are defined in Recommendation\ X.340.
.PP
\fINote\ 2\fR \ \(em\ Common channel signalling network (CCSN) is also
considered in this Recommendation, for interworking with PDNs, and to provide
a means of data transmission of operational information (see also \(sc\
5.5, in particular the \*Qnote\*U in \(sc\ 5.5.2).
.RT
.sp 2P
.LP
5.1
\fIPacket switched public data network (PSPDN)\fR
.sp 1P
.RT
.PP
5.1.1
The packet switched public data networks (PSPDNs) are
considered in this Recommendation.
.sp 9p
.RT
.PP
5.1.2
The data transmission services and user facilities offered through the
PSPDNs are described in Recommendations\ X.1 and\ X.2, and are the packet
switched data transmission services.
.PP
5.1.3
The categories of access for DTEs to the data transmission
services offered through PSPDNs are specified in Recommendation\ X.10.
.PP
5.1.4
In addition to data transmission services and telematic services, PSPDNs
can be used to support OSI applications.
.sp 2P
.LP
5.2
\fICircuit switched public data network (CSPDN)\fR
.sp 1P
.RT
.PP
5.2.1
The circuit switched public data networks (CSPDNs) are
considered in this Recommendation.
.sp 9p
.RT
.PP
5.2.2
The data transmission services and user facilities offered through the
CSPDNs are described in Recommendations\ X.1 and\ X.2, and are:
.LP
\(em
either synchronous data transmission services;
.LP
\(em
or asynchronous data transmission services.
.PP
5.2.3
The categories of access for DTEs to the data transmission
services offered through CSPDNs are specified in Recommendation\ X.10.
.PP
5.2.4
In addition to data transmission services and telematic services, a CSPDN
can be used to support OSI applications.
.PP
\fINote\fR \ \(em\ The extent to which CSPDNs provide support for the full
capability of the OSI connection\(hymode network service, is for further
study. It is intended to reflect the result of this study in the present
Recommendation, when appropriate.
.sp 2P
.LP
5.3
\fIIntegrated services digital network (ISDN)\fR
.sp 1P
.RT
.PP
5.3.1
The integrated services digital network (ISDN) is considered in this Recommendation
for the interworking for the provision of data transmission services.
.sp 9p
.RT
.PP
\fINote\fR \ \(em\ one objective of the ISDN is to provide data transmission
services currently provided through PDNs (see I.230\(hyseries Recommendations).
.bp
.PP
5.3.2
The data transmission services related to ISDN considered in this Recommendation
are described in Recommendation\ X.1, and are:
.LP
a)
circuit switched data transmission services;
.LP
b)
packet switched data transmission services.
.PP
\fINote\fR \ \(em\ In addition, other types of data transmission services
may have to be considered for interworking with the ISDN for new applications
(e.g.\ telemetry).
.PP
5.3.3
The categories of access for DTEs to the data transmission
services on ISDN are described in Recommendation\ X.10.
.sp 2P
.LP
5.4
\fIPublic switched telephone network (PSTN)\fR
.sp 1P
.RT
.PP
5.4.1
The public switched telephone network (PSTN) is considered in this Recommendation
for the interworking for the provision of data transmission services.
.sp 9p
.RT
.PP
\fINote\fR \ \(em\ PSTN with or without enhanced signalling capability
(e.g.\ calling line identification capability) should be considered for
interworking.
.PP
5.4.2
The data transmission services which should be considered through the PSTN
for interworking with PDNs depend on the exact interworking situation (see
also \(sc\ 8). Depending on the interworking situation, such data transmission
services are either based on synchronous or asynchronous data transmission
services, or based on packet switched data transmission services which are
expected to be equivalent to the OSI connection\(hymode network service.
.sp 2P
.LP
5.5
\fICommon channel signalling network (CCSN)\fR
.sp 1P
.RT
.PP
5.5.1
The purpose of a common channel signalling network (CCSN) is to control
signalling for another network (e.g.\ ISDN, CSPDN).
.sp 9p
.RT
.PP
The controlled network may interwork with another PDN, as
illustrated in Figure\ 5\(hy1/X.300. Such an interworking is not considered as
interworking between CCSN and PDN in this Recommendation.
.LP
.rs
.sp 14P
.ad r
\fBFigure 5\(hy1/X.300 p.\fR
.sp 1P
.RT
.ad b
.RT
.PP
5.5.2
For the transmission of operational information between
Administrations, CCSN and PDN may also need to interwork at the same level,
to provide a means of data transmission between operational centres and/or
terminals for those Administrations, as illustrated in Figure\ 5\(hy2/X.300.
Such an interworking is to be considered as interworking between CCSN and
PDN (see Note).
.PP
\fINote\fR \ \(em\ This does not preclude consideration of the interworking
between PDNs and common channel signalling networks for the transfer of
user
data. The provision of this capability is for further study.
.bp
.LP
.rs
.sp 16P
.ad r
\fBFigure 5\(hy2/X.300 p.\fR
.sp 1P
.RT
.ad b
.RT
.PP
5.5.3
A CCSN, for the interworking with a PDN and for the transmission of operational
information, should be considered, in association with any
appropriate interworking function, for the provisin of the OSI
connection\(hy
mode network service.
.sp 2P
.LP
5.6
\fIPublic Mobile systems\fR
.sp 1P
.RT
.sp 1P
.LP
5.6.1
\fIPublic Mobile satellite data transmission systems\fR
.sp 9p
.RT
.PP
5.6.1.1
The general interworking requirements for data transmission in public mobile
satellite systems are defined in Recommendation\ X.350.
.sp 9p
.RT
.PP
5.6.1.2
The requirements for interworking between PSPDNs and the public
mobile satellite service using a PAD are given in Recommendation\ X.351.
.PP
5.6.1.3
The requirements for interworking by call control mapping between packet
switched public data networks (PSPDNs) and public mobile satellite data
transmission systems are defined in Recommendation\ X.352.
.sp 2P
.LP
5.6.2
\fIPublic land mobile networks (PLMNs)\fR
.sp 1P
.RT
.PP
5.6.2.1
Interworking between PSPDNs and PLMNs employing analogue radio transmission
techniques may be obtained through IWFs designed in accordance
with Recommendation\ X.32. In this case, the telephone channels of the public
mobile system are used as access circuits to the IWF. The PLMN may also be
interconnected with the PSPDN via switched circuit of the PSTN.
.sp 9p
.RT
.PP
5.6.2.2
Interworking between PSPDNs and ISDNs and PLMNs with access
capabilities equivalent to that of the ISDN is for further study.
.PP
5.6.2.3
CSPDNs may be used to access PLMNs in the same way as defined in \(sc\
5.6.2.1 using protocols providing error correction and flow control. This
point is for further study.
.sp 1P
.LP
5.6.3
\fIOther mobile systems\fR
.sp 9p
.RT
.PP
Interworking with public mobile systems in cases other than those given
above, is for further study.
.RT
.sp 1P
.LP
5.7
\fIPrivate Networks\fR
.sp 9p
.RT
.PP
Private networks are considered for interworking with PSPDNs and
ISDNs for the provision of data transmission services (see
Recommendation\ X.327).
.PP
\fINote\fR \ \(em\ Interworking with CSPDNs is for further study.
.RT
.LP
.bp