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.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'
.IP
\fB7.7\fR 	\fBOperations, administration and maintenance features of
transmission equipment\fR 
.sp 1P
.RT
.sp 2P
.LP
\fBRecommendation G.771\fR 
.RT
.sp 2P
.ce 1000
\fBQ\(hyINTERFACES\ AND\ ASSOCIATED\ PROTOCOLS\ FOR\ TRANSMISSION\ EQUIPMENT\fR 
.EF '%	Fascicle\ III.4\ \(em\ Rec.\ G.771''
.OF '''Fascicle\ III.4\ \(em\ Rec.\ G.771	%'
.ce 0
.sp 1P
.ce 1000
\fBIN\ THE\ TELECOMMUNICATIONS\ MANAGEMENT\ NETWORK\ (TMN)\fR 
.ce 0
.sp 1P
.ce 1000
\fI(Melbourne, 1988)\fR 
.sp 9p
.RT
.ce 0
.sp 1P
.LP
\fB1\fR 	\fBIntroduction\fR 
.sp 1P
.RT
.sp 1P
.LP
1.1
	\fIScope\fR 
.sp 9p
.RT
.PP
This Recommendation defines the Q\d1\uand Q\d2\uinterfaces and
associated protocols required to connect transmission equipment to a TMN as
defined in Recommendation\ M.30. Although primarily intended for use on
transmission equipment, these interfaces may be used in other applications 
when appropriate. 
.PP
A limited set of protocol suites is defined, from which an
Administration may select those appropriate to their needs. Guidance is 
given on a suitable selection process. The set of protocol suites does 
not yet 
include a protocol suite capable of interworking with ISDN.
.RT
.sp 1P
.LP
1.2
	\fITelecommunication management network\fR 
.sp 9p
.RT
.PP
A telecommunications management network (TMN) provides the means to transport 
and process information related to network operations, 
administration and maintenance. General principles of the TMN are described 
in Recommendation\ M.30. Figure\ 1/G.771 shows an example of the physical 
architecture for a TMN.
.RT
.sp 2P
.LP
\fB2\fR 	\fBReferences\fR \v'3p'
.sp 1P
.RT
.LP
	Recommendation M.30
	\(em
	General principles of a TMN
.LP
	Recommendation X.200
	\(em
	Reference model of OSI for CCITT
applications
.LP
	Recommendation Q.513
	\(em
	Interfaces for operations,
administration and maintenance
.sp 2P
.LP
\fB3\fR 	\fBDefinitions\fR 
.sp 1P
.RT
.sp 1P
.LP
3.1
	\fIDefinitions associated with the TMN architecture\fR 
.sp 9p
.RT
.PP
Definitions of terms relative to the TMN architecture are defined in Recommendation\ 
M.30. 
.RT
.sp 2P
.LP
3.2
	\fIAdditional definitions\fR 
.sp 1P
.RT
.sp 1P
.LP
3.2.1
	\fBapplication messages\fR 
.sp 9p
.RT
.PP
Application messages are the messages flowing on the local
communication network (LCN) and the data communication network (DCN) to meet
the needs of TMN application functions.
.RT
.sp 1P
.LP
3.2.2
	\fBapplication message characteristics\fR 
.sp 9p
.RT
.PP
Application message characteristics are the application message
attributes and information contents of the application messages.
.RT
.sp 1P
.LP
3.2.3
	\fBapplication message attributes\fR 
.sp 9p
.RT
.PP
Application message attributes are the attributes that
characterize the requirements of communication functions for application
messages in the LCN and DCN.
.bp
.RT
.LP
.rs
.sp 39P
.ad r
\fBFigure 1/G.771, p. 1\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
3.2.4
	\fBapplication message information contents\fR 
.sp 9p
.RT
.PP
Application message information contents provide the structure and the 
meaning of application messages in the LCN and in the DCN. 
.RT
.sp 1P
.LP
3.2.5
	\fBphysical configuration attributes\fR 
.sp 9p
.RT
.PP
Physical configuration attributes are those characteristics
related to the physical configuration of the LCN and the DCN.
.RT
.sp 1P
.LP
3.2.6
	\fBprotocol selection attributes\fR 
.sp 9p
.RT
.PP
Protocol selection attributes are those characteristics of
protocol suites related to their ability to meet the communication needs of
application messages in the LCN and the DCN.
.bp
.RT
.sp 2P
.LP
\fB4\fR 	\fBQ\(hyinterfaces\fR 
.sp 1P
.RT
.sp 1P
.LP
4.1
	\fIPurpose\fR 
.sp 9p
.RT
.PP
The Q\(hyinterfaces provide for the interconnection of network
elements (NEs), operations systems (OSs) and mediation devices (MDs)
through the DCN and/or LCN. The purpose of an interface specification is to
assure compatibility of devices interconnected, to accomplish a given TMN
application function independent of the type of device or of the supplier.
.PP
The main purpose of the messages flowing over the Q\(hyinterfaces is to 
facilitate information exchange between network element functions and operation 
system functions. It is the task of the mediation function to extract or 
map 
the information from the one to the other. A list of mediation functions is
given in Recommendation\ M.30. The definition of mediation devices requires
further study.
.PP
The message transfer via the Q\(hyinterface requires the use of
protocols. This Recommendation specifies a limited set of protocols, based 
on the\ 7 layer OSI model, which take into consideration the division of 
functions, interface attributes and economics. 
.RT
.sp 1P
.LP
4.2
	\fIGeneral physical characteristics of Q\(hyinterfaces\fR 
.sp 9p
.RT
.PP
The Q\(hyinterfaces are used for all communications within the TMN.
(Annex\ A provides some examples.) A physical Q\(hyinterface appears at, or as
close as possible to, a device. A device is a physical implementation of a
function.
.PP
The DCN is used for communications between central operations systems and 
distributed telecommunications centres. It interfaces at the Q\d3\ustandard 
interface (see Recommendation\ Q.513). 
.PP
The highest level of MDs and OSs are implemented using the Q\d3\uinterface. 
For practical reasons, an NE incorporating mediation functions may be provided 
with a Q\d3\uinterface to communicate directly with OSs using the DCN. 
.PP
The LCN connects at Q\d1\uand Q\d2\ustandard interfaces as defined in this 
Recommendation. When operational or economic factors dictate, the LCN may 
also connect remote NEs to local MDs or to local NEs which incorporate 
mediation functions.
.PP
NEs containing no mediation functions are connected to MDs using the Q\d1\uinterface. 
NEs containing some mediation functions are connected to MDs using the 
Q\d2\uinterface. The Q\d2\uinterface is also used for the connection between 
different MDs. 
.PP
The Q\(hyinterfaces may also be used with Q\(hyinterface adapters for
connecting the equipment with non\(hystandardized M\(hyinterfaces, as specified 
in 
Recommendation\ M.30. Examples of using Q\(hyinterface adapters are provided in
Annex\ A.
.RT
.sp 1P
.LP
4.3
	\fIGeneral protocol characteristics\fR 
.sp 9p
.RT
.PP
The characteristics of the protocols associated with the
Q\(hyinterfaces depend upon the functions to be performed. The need for two
families of protocols, based on the\ 7 layer OSI model have been identified. 
The PQ(dcn) family, associated with Q\d3\uinterface, is more complex than 
the 
PQ(lcn) family, associated with Q\d1\uand Q\d2\uinterfaces which are capable 
of a more limited set of functions. Within the PQ(lcn) family, the protocol 
suites associated with the Q\d1\uinterface will generally be simpler than 
those 
associated with Q\d2\u.
.PP
Physical configuration attributes characterize the physical
configuration of a set of MDs and NEs in a given implementation, and are
important factors in the selection of protocol suites of the PQ(lcn) family 
of protocols. 
.PP
Some LCN physical configuration attributes are provided in
Annex\ B.
.RT
.sp 2P
.LP
\fB5\fR 	\fBPQ(lcn) family of protocol suites\fR 
.sp 1P
.RT
.sp 1P
.LP
5.1
	\fIPurpose\fR 
.sp 9p
.RT
.PP
The purpose of the PQ(lcn) family of protocol suites is to enable efficient 
communications to take place between mediation devices and network 
elements, and/or between mediation devices across the Q\d1\uand Q\d2\uinterfaces 
within the telecommunication management network. 
.bp
.RT
.sp 1P
.LP
5.2
	\fIDescription of the family\fR 
.sp 9p
.RT
.PP
The family of PQ(lcn) protocol suites consists of a limited number of members. 
Each family member is a particular protocol suite and is 
distinguishable from other family members by protocol attributes defined
in\ \(sc\ 5.3.4.
.PP
A protocol suite consists of OSI layers\ 1\(hy7. Not all layers of the 
OSI model have to be provided for the PQ(lcn) family of protocol suites. 
.RT
.sp 2P
.LP
5.3
	\fIGuide to\fR 
\fIprotocol suite selection\fR 
.sp 1P
.RT
.sp 1P
.LP
5.3.1
	\fIPurpose\fR 
.sp 9p
.RT
.PP
The purpose of this section is to define the process and to provide the 
information that is necessary to allow the selection of protocol suites 
from the sets of the PQ(lcn) family of protocols provided in\ \(sc\ 5.4.
.RT
.sp 1P
.LP
5.3.2
	\fIPQ(lcn) protocol suite selection process\fR 
.sp 9p
.RT
.PP
The following steps are involved in an iterative manner to select the protocol 
suites that will satisfy user needs: 
.RT
.LP
	i)
	 identify TMN application functions that will be carried by the LCN, as 
per Recommendation\ M.30; 
.LP
	ii)
	identify the distribution of mediation functions;
.LP
	iii)
	identify the physical configuration attributes of the
LCN;
.LP
	iv)
	define the TMN application messages to be carried on the
LCN;
.LP
	v)
	 prepare individual TMN application message characteristics which meet 
the needs of the TMN application functions. These are the 
characteristics of application messages that are to be carried on the LCN, 
on the basis of a set of application message characteristics provided in\ 
\(sc\ 5.3.3; 
.LP
	vi)
	 analyze both the physical configuration attributes and the individual 
application message characteristics in order to associate these with protocol 
selection attributes provided in \(sc\ 5.3.4; 
.LP
	vii)
	 select appropriate protocol suites which meet the needs of TMN application 
functions by associating the protocol selection attributes with members 
of the PQ(lcn) family of protocol suites. 
.PP
\fINote\fR \ \(em\ Figure 2/G.771 pictures the steps vi) and vii) of the
selection process above. It should be noted that the application message
characteristics pose requirements on the services provided at the application 
layer, which is the collective view of the services provided at all layers, 
whereas the protocol selection attributes are given for each OSI layer
individually.
.LP
.rs
.sp 21P
.ad r
\fBFigure 2/G.771, p.  \fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
5.3.3
	\fITMN application message characteristics\fR 
.sp 9p
.RT
.PP
There are two types of characteristics that must be considered in the evaluation 
of application messages: 
.RT
.LP
	\(em
	application message attributes;
.LP
	\(em
	application message information contents.
.PP
Annex C provides a list of possible LCN application message
characteristics that can be applied to application messages.
.PP
Annex D provides an example of application messages profile
characterization.
.PP
The values and names associated with application message
characteristics in the LCN must be consistent with the values and names
associated with overall TMN application message characteristics.
.RT
.sp 1P
.LP
5.3.4
	\fILCN protocol selection attributes\fR 
.sp 9p
.RT
.PP
Annex E provides some LCN protocol selection attributes.
.RT
.sp 1P
.LP
5.4
	\fIProtocol suites\fR 
.sp 9p
.RT
.PP
This section defines the protocol suites to be used to support
Q\d1\uand Q\d2\uinterfaces and lists the protocol selection attribute values
for each protocol suite.
.RT
.sp 1P
.LP
5.4.1
	\fIProtocol selection attribute values\fR 
.sp 9p
.RT
.PP
A table identifying the protocol selection attributes for each of the protocol 
suites defined in this Recommendation will be provided when 
protocol suites are included in the PQ(lcn) family.
.PP
Table F\(hy5/G.771 provides an example of such a table for candidate
protocol suites.
.RT
.sp 1P
.LP
5.4.2
	\fIProtocol suite definitions\fR 
.sp 9p
.RT
.PP
Several proposed candidate protocol suites can be found in
Annex\ F. The choice of candidates for this section is under study.
\v'6p'
.RT
.ce 1000
ANNEX A
.ce 0
.ce 1000
(to Recommendation G.771)
.sp 9p
.RT
.ce 0
.ce 1000
\fBExamples of\fR 
\fBphysical implementations using TMN architecture\fR 
.sp 1P
.RT
.ce 0
.PP
The following are some of the equipments covered by
Recommendation\ G.771:
.sp 1P
.RT
.LP
	\(em
	 transmission terminals (multiplexers, digital cross\(hyconnects, channel 
translation equipments, etc.); 
.LP
	\(em
	 digital and analogue transmission systems (via metallic and fibre cables, 
via radio and satellite, etc.); 
.LP
	\(em
	associated support systems (test modules, power supply
systems, building alarm systems, fault location systems, etc.).
.PP
Examples of physical implementations using TMN architecture are
shown in the following figures, A\(hy1/G.771 and A\(hy2/G.771.
.bp
.LP
.rs
.sp 47P
.ad r
\fBFigure A\(hy1/G.771, p. 3\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 47P
.ad r
\fBFigure A\(hy2/G.771, p. 4\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce 1000
ANNEX B
.ce 0
.ce 1000
(to Recommendation G.771)
.sp 9p
.RT
.ce 0
.ce 1000
\fBLCN physical configuration attributes\fR 
.sp 1P
.RT
.ce 0
.PP
The LCN physical configuration attributes represent the
requirements an Administration imposes on the configuration of the whole 
of the particular LCN to be designed. In the PQ(lcn) protocol suite selection 
process (\(sc\ 5.3.2), the LCN physical configuration attributes will not 
only influence 
the choice of PQ(lcn) protocol suite, but also determine the type and quantity 
of mediation devices needed. 
.sp 1P
.RT
.PP
During the design of the LCN the Administration may also consider the number 
of ports per configuration and the number of such configurations 
that can be served by a particular mediation device that implements the
selected protocol suite. Together with the distribution of network elements
over space and the extent of cascading the mediation devices, this leads 
to the layout of the LCN. However, such mediation device design characteristics 
are beyond the scope of this Recommendation. 
.PP
Some LCN physical configuration attributes are:
.RT
.sp 1P
.LP
B.1
	\fINumber of NE ports\fR 
.sp 9p
.RT
.PP
Specifies how many network element local communication ports are to be 
served by an LCN (including mediation devices). 
.RT
.LP
	Descriptor: (ports)
	small
	\(= 32
.LP
	medium
	> 32, \(= 256
.LP
	large
	> 256, \(= 2048
.LP
	very large
	> 2048
.sp 1P
.LP
B.2
	\fIConfiguration\fR 
.sp 9p
.RT
.PP
Specifies the configuration to be used for the LCN.
.RT
.LP
	Descriptor:
	star;
.LP
	bus;
.LP
	ring.
.sp 1P
.LP
B.3
	\fINumber of ports per configuration\fR 
.sp 9p
.RT
.PP
Specifies how many ports are to be interconnected within a single configuration 
(star, bus or ring) of the LCN. 
.PP
For a star configuration, count the number of branches since one port per 
branch is implicitly assumed. For master\(hyslave protocol suites for the 
bus or ring configuration, the master is excluded from the count of ports 
per 
configuration.
.RT
.LP
	Descriptor: (ports)
	small
	\(= 8
.LP
	medium
	> 8, \(= 32
.LP
	large
	> 32, \(= 128
.LP
	very large
	> 128
.sp 1P
.LP
B.4
	\fICommunication distance\fR 
.sp 9p
.RT
.PP
Specifies the distance to be bridged within the LCN.
.RT
.LP
	Descriptor: (metres)
	very short
	\(= 10
.LP
	short
	> 10, \(= 100
.LP
	medium
	> 100, \(= 1000
.LP
	long
	> 1000
.sp 1P
.LP
B.5
	\fICommunication environment\fR \v'3p'
.sp 9p
.RT
.LP
	Descriptor:
	within\(hyrack;
.LP
	on the same floor;
.LP
	in\(hybuilding;
.LP
	out of building.
.PP
B.6
The need to provide further attributes is for further study.
.bp
.sp 9p
.RT
.ce 1000
ANNEX C
.ce 0
.ce 1000
(to Recommendation G.771)
.sp 9p
.RT
.ce 0
.ce 1000
\fBLCN application message characteristics\fR 
.sp 1P
.RT
.ce 0
.LP
C.1
	\fIApplication message attributes\fR 
.sp 1P
.RT
.sp 1P
.LP
C.1.1
	\fICommunication pattern\fR \v'3p'
.sp 9p
.RT
.LP
	Response\ \(em\ subordinate node only answers questions and executes
explicit commands.
.LP
	Autonomous\ \(em\ subordinate node can also provide the master with
other information (e.g. when polled).
.LP
	Peer\ \(em\ subordinate node can also communicate with other
subordinate nodes.
.sp 1P
.LP
C.1.2
	\fIData quantity\fR 
.sp 9p
.RT
.PP
Amount of data transferred. General criteria of 4096 octets and
256\ octets can be used as descriptor.
.RT
.LP
	Descriptor: (octets)
	low
	\(= 256
.LP
	medium
	> 256, \(= 4096
.LP
	large
	> 4096
.sp 1P
.LP
C.1.3
	\fIFrequency\fR 
.sp 9p
.RT
.PP
Describes how often the message instance is expected to use the
LCN.
.RT
.LP
	Descriptor:\ (transactions\ per\ day)
	seldom
	\(= 1
.LP
	periodic
	> 1, \(= 1440
.LP
	often
	> 1440
.sp 1P
.LP
C.1.4
	\fIDelay\fR 
.sp 9p
.RT
.PP
Defines the amount of delay that can be accepted in LCN
communication. Delay here does not include mediation processing time.
.RT
.LP
	Descriptor: (seconds)
	short
	\(= 1
.LP
	medium
	> 1, \(= 10
.LP
	long
	> 10
.sp 1P
.LP
C.1.5
	\fIMultiple responses\fR 
.sp 9p
.RT
.PP
Denotes that there can be more than one response to a request from the 
same source. 
.PP
Descriptor: single, multiple.
.RT
.sp 1P
.LP
C.1.6
	\fIPriority\fR 
.sp 9p
.RT
.PP
States the order of importance, or priority associated with a
message.
.PP
Descriptor: yes, no.
.RT
.sp 1P
.LP
C.1.7
	\fIReceipt confirmation\fR 
.sp 9p
.RT
.PP
Critical messages communicated from one system may require
confirmation that the peer system is in receipt of that specific data.
.PP
Descriptor: yes, no.
.RT
.sp 1P
.LP
C.1.8
	\fIReliability\fR 
.sp 9p
.RT
.PP
Describes whether information can be lost or affected by
transmission in the LCN.
.RT
.LP
	Descriptor:\ (error)
	low:
	no requirement;
.LP
	medium:
	infrequent;
.LP
	high:
	none.
.bp
.sp 1P
.LP
C.1.9
	\fIPhase commit\fR 
.sp 9p
.RT
.PP
Required if a series of actions must be carried out in a
coordinated manner by one or more NEs under supervision of MD.
.PP
Descriptor: yes, no.
.RT
.sp 1P
.LP
C.1.10
	\fIAvailability\fR 
.sp 9p
.RT
.PP
The amount of isolation that can be tolerated from impairments in   the LCN.
.RT
.LP
	Descriptor: (%)
	low
	> 85
.LP
	medium
	> 95
.LP
	high
	> 99.5
.sp 1P
.LP
C.1.11
	\fIData organization\fR 
.sp 9p
.RT
.PP
Describes whether the information is organized in files and the
type of data organization associated.
.PP
Descriptor: (data organization) yes, no.
.RT
.sp 1P
.LP
C.2
	\fIApplications message information content\fR 
.sp 9p
.RT
.PP
The list below provides types of data elements that are common
across operations functions. As such they will allow a structure to be 
provided for the information contained in specific messages and thus be 
eventually 
mapped into a notation associated with the LCN protocol.
.PP
The common data elements described below may not all be needed for
every individual LCN nor will they necessarily be organized in the order 
given below. 
.RT
.sp 1P
.LP
C.2.1
	\fIType of message\fR 
.sp 9p
.RT
.PP
Refers to the mode of interaction and not the specific operation
functions invoked by the message.
.PP
Example: message type (report, command, etc.).
.RT
.sp 1P
.LP
C.2.2
	\fIType of resource\fR 
.sp 9p
.RT
.PP
Refers to the general network entity which is being managed.
.PP
Examples: fibre optic system; model\ X.
.RT
.sp 1P
.LP
C.2.3
	\fIInstance of resource\fR 
.sp 9p
.RT
.PP
Refers to the specific instance of the NE which is being managed, such 
as model\ X, number\ Y. 
.RT
.sp 1P
.LP
C.2.4
	\fIDate/time\fR 
.sp 9p
.RT
.PP
May or may not be applicable.
.RT
.sp 1P
.LP
C.2.5
	\fIName of the message\fR 
.sp 9p
.RT
.PP
Refers to the specific operation being performed.
.PP
Examples: equipment alarm report; equipment control command; facility performance 
report. 
.RT
.sp 1P
.LP
C.2.6
	\fIResource sub\(hyentity\fR 
.sp 9p
.RT
.PP
Refers to the detailed resource sub\(hyentity targeted by the
operation.
.PP
Examples: fibre optic transmitter; primary rate circuit.
.RT
.sp 1P
.LP
C.2.7
	\fIResource sub\(hyentity instance\fR 
.sp 9p
.RT
.PP
Identification of the particular instance of the resource
sub\(hyentity.
.PP
Example: fibre optic transmitter No.\ 5.
.bp
.RT
.sp 1P
.LP
C.2.8
	\fIMessage parameters\fR 
.sp 9p
.RT
.PP
Refers to data elements that are specific to the message name.
.PP
Examples: major or minor; error\(hyfree seconds.
.RT
.sp 1P
.LP
C.2.9
	\fIResult parameters\fR 
.sp 9p
.RT
.PP
These are the data elements that represent the values that, where applicable, 
will be associated with message parameters or other data 
elements.
.PP
Example: 100 error\(hyfree seconds.
.RT
.sp 1P
.LP
C.2.10
	\fIError message type\fR 
.sp 9p
.RT
.PP
Category of reply to unsuccessful information exchange attempt.
.PP
Example: invalid alarm type.
.RT
.sp 1P
.LP
C.2.11
	\fIError message parameters\fR 
.sp 9p
.RT
.PP
Parameters that may accompany error message types.
.RT
.sp 1P
.LP
C.2.12
	\fIMultiple response names\fR 
.sp 9p
.RT
.PP
This data element is a combination of other data elements in the
situation where a specific message is part of a suitable response chain, for
example, where individual messages must be referred to an initiating
message.
.RT
.sp 1P
.LP
C.2.13
	\fIMultiple response parameters\fR 
.sp 9p
.RT
.PP
Output data elements associated with multiple response names.
.RT
.LP
.rs
.sp 26P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.ce 1000
ANNEX\ D
.ce 0
.ce 1000
(to Recommendation G.771)
.sp 9p
.RT
.ce 0
.ce 1000
\fBExamples of\fR 
\fBapplication message profile characterization\fR 
.sp 1P
.RT
.ce 0
.PP
\fIExample of fibre optic transmission system\fR 
.sp 1P
.RT
.LP
.sp 1
.LP
Major Alarm Report
\v'1P'
APPLICATION MESSAGE ATTRIBUTES:
.LP
\ 1.
INITIATOR
NE\ 
	\ 2.
DATA QUANTITY
Low 
	\ 3.
FREQUENCY
Seldom 
	\ 4.
DELAY
High 
	
.LP
\ 5.
MULTIPLE RESPONSES
Not applicable 
	\ 6.
PRIORITY
Yes 
	\ 7.
RECEIPT CONFIRMATION
? 
	\ 8.
RELIABILITY
High 
	
.LP
\ 9.
PHASE COMMIT
Not applicable 
	10.
AVAILABILITY
High 
	11.
DATA ORGANIZATION
Not applicable 
	
.LP
\v'1P'
APPLICATION MESSAGE INFORMATION CONTENT:
\ 1.
TYPE OF MESSAGE
Report 
	\ 2.
TYPE OF RESOURCE
Fibre optic transmission system
XYZ 
	
.LP
\ 3.
INSTANCE OF RESOURCE
Unit number N 
	\ 4.
DATE/TIME
YYYY/MM/DD 
\ 
\ 
HR/MIN/SEC 
	\ 5.
NAME OF MESSAGE
Equipment alarm report 
	\ 6.
RESOURCE SUB\(hyENTITY
Transmit unit 
	
.LP
\ 7.
RESOURCE SUB\(hyENTITY INSTANCE
Channel number M 
	\ 8.
MESSAGE PARAMETER
Laser failure 
	\ 9.
RESULT PARAMETERS
Not applicable 
	10.
ERROR MESSAGE TYPE
Not applicable 
	
.LP
11.
ERROR MESSAGE PARAMETERS
Not applicable 
	12.
MULTIPLE RESPONSE NAMES
Not applicable 
	13.
MULTIPLE RESPONSE PARAMETERS
Not applicable 
	.bp
.ce 1000
ANNEX E
.ce 0
.ce 1000
(to Recommendation G.771)
.sp 9p
.RT
.ce 0
.ce 1000
\fBLCN protocol selection attributes\fR 
.sp 1P
.RT
.ce 0
.PP
These LCN protocol selection attributes summarize the capabilities of the 
individual PQ(lcn) protocol suites for use in the LCN protocol suite 
selection process described in\ \(sc\ 5.3.2.
.sp 1P
.RT
.PP
\fINote\fR \ \(em\ Abbreviations are given for each allowed attribute value 
as a key to Table\ F\(hy5/G.771, which groups all the candidate selection 
attribute values. 
.PP
The protocol selection attributes are:
.RT
.LP
.sp 1
.LP
	a)
	At layer 1:
.LP
Configuration
S:
	star; B: bus; R: ring 
	Number of ports per configuration (ports)
S:
	small \(= 8
	
.LP
M:
	medium > 8, \(= 32
	L:
	large > 32, \(= 128
	VL:
	very large > 128
	Physical medium
SP:
	screened pair; TP: twisted pair;
	
.LP
CP:
	coaxial pair; OF: optical fibre;
	O:
	other
	Transmission mode
S:
	synchronous; AS: asynchronous;
	HD:
	half duplex; FD: full duplex
	
.LP
Operating speed (bits per second)
1200; 2400; 4800; 9600; 19\ 200; 64 | 00; 128\ 000; 1 | 00 | 00
Communication distance (metres)
VS:
	very short \(= 10
	S:
	short > 10, \(= 100
	
.LP
M:
	medium > 100, \(= 1000
	L:
	long > 1000
	Communication environment
WR:
	within\(hyrack; OF: on the same floor;
	IB:
	in\(hybuilding; OB: out of building
	
.LP
Availability (%)
L:
	low 
	?04
	M:
	medium
	?05\ under study
.LP
	H:
	high 
	\(rb
	
.sp 1P
.LP
	b)
	At layer 2:
.sp 9p
.RT
.LP
Data link connection
CO:
	connection oriented
	CL:
	connection\(hyless
	Data link initiator
M:
	master; AP: all participants
	
.LP
Data link address size (addresses)
S:
	small \(= 8 
	M:
	medium > 8, \(= 32
	L:
	large > 32, \(= 128
	VL:
	very large > 128
	Receipt confirmation
Y:
	yes; N: no
	
.LP
Maximum frame size (octets)
S:
	small \(= 256
	M:
	medium > 256, \(= 4096
	L:
	large > 4096
	Max. frame frequency per port (frames per second)
L:
	low \(= 1/60
	
.LP
M:
	medium > 1/60, \(= 1
	H:
	high > 1
	.bp
.LP
Max. frame transmit delay (seconds)
S:
	short \(= 0.1
	M:
	medium > 0.1, \(= 1
	L:
	long > 1
	Error detection
N:
	none; P: parity, CS: checksum (n);
	
.LP
CRC:
	cyclic redundancy check (n)
	Hamming distance
1; 2; 3; 4; n
	Error recovery
N:
	none; R: repetition; C: correction
	
.sp 1P
.LP
	c)
	At layer 3:
.sp 9p
.RT
.LP
LCN network size (ports)
S:
	small \(= 32
	M:
	medium > 32, \(= 256
	L:
	large > 256, \(= 2048
	VL:
	very large > 2048
	
.LP
Routing
Y:
	yes; N: no
	(Un) packing
Y:
	yes; N: no
	Connections
N:
	none; P: permanent; SW: switched
	
.sp 1P
.LP
Priority
Y:
	yes; N: no
		d)
	The other layers are for further study.
.sp 9p
.RT
.ce 1000
ANNEX F
.ce 0
.ce 1000
(to Recommendation G.771)
.sp 9p
.RT
.ce 0
.ce 1000
\fBProposed candidate protocol suites\fR 
.sp 1P
.RT
.ce 0
.PP
This annex contains the candidate protocol suites currently
under consideration for selection as members of the PQ(lcn) family of protocol 
suites. The description of the individual protocol suites is of varying 
completeness, but each description is limited to the specification of the 
lower two or three OSI layers. For a complete protocol suite specification, 
higher 
layers must be defined; however, the available information is provided 
here to guide hardware decisions. The completion of the descriptions and 
the selection is for further study. 
.sp 1P
.RT
.PP
Candidate protocol suite No. 3 has the widest support, but no
candidate protocol suite has yet been subjected to a formal selection process 
by CCITT. 
.PP
Each candidate protocol suite is described in the following sections. Following 
the descriptions is a summary section which contains in 
Table\ F\(hy5/G.771 the candidate protocol selection attribute values (see
Annex\ E). Differences of the values in Table\ F\(hy5/G.771 indicate differences 
in capabilities which may affect the suitability of individual candidates 
for 
particular application areas.
.PP
Some initial applications are indicated for each candidate protocol
suite. However, the range of applications appropriate to these suites has 
not been thoroughly examined. 
.RT
.sp 1P
.LP
F.1
	\fICandidate protocol suite No.\ 1 (CPS\ 1)\fR 
.sp 9p
.RT
.PP
Initial application:
.PP
Alarm surveillance, performance monitoring and configuration control of 
NEs found in reasonably large numbers in the telecommunications network 
(e.g. muldex, line transmission terminal).
.bp
.RT
.sp 2P
.LP
F.1.1
	\fIOSI layer 1\fR 
.sp 1P
.RT
.sp 1P
.LP
F.1.1.1
	\fIConfiguration\fR 
.sp 9p
.RT
.PP
One serial bus connects up to 30 nodes.
.PP
Configurations with more than 30 nodes can be realized by a
hierarchical structure of several serial buses.
.PP
Such a hierarchical structure is characterized by a high throughput
with a low transmission rate per bus.
.RT
.sp 1P
.LP
F.1.1.2
	\fICommunication environment\fR 
.sp 9p
.RT
.PP
The serial bus configuration shall be used only for in\(hybuilding
application.
.RT
.sp 1P
.LP
F.1.1.3
	\fIPhysical connection\fR 
.sp 9p
.RT
.PP
One balanced, screened pair with a maximum length of\ 500
metres.
.RT
.sp 1P
.LP
F.1.1.4
	\fIElectrical requirements\fR 
.sp 9p
.RT
.PP
Each bus interface shall be in accordance with Recommendation\ V.11 multipoint 
interconnections [1, 3, 14, and 23]. 
.PP
Each bus shall be terminated by resistors in accordance with\ [23].
.PP
Each receiver shall present a maximum of one unit load to the bus, as defined 
in\ [23]. 
.RT
.sp 1P
.LP
F.1.1.5
	\fILine code\fR 
.sp 9p
.RT
.PP
The line code shall be NRZ (non\(hyreturn to zero).
.RT
.sp 1P
.LP
F.1.1.6
	\fISpeed\fR 
.sp 9p
.RT
.PP
The bit rate shall be 19.2 kbitB/Fs.
.PP
The bit rate tolerance shall be \(+-\ 1%.
.RT
.sp 1P
.LP
F.1.1.7
	\fITransmission mode\fR 
.sp 9p
.RT
.PP
The transmission mode shall be half duplex, asynchronous.
.RT
.sp 1P
.LP
F.1.2
	\fIOSI layer 2\fR 
.sp 9p
.RT
.PP
Asynchronous, byte oriented protocol according to\ [15].
.RT
.sp 1P
.LP
F.1.2.1
	\fITransmission frame format\fR 
.sp 9p
.RT
.PP
The transmission frame format shall be in accordance with
[15\ (i)].
.RT
.sp 1P
.LP
F.1.2.2
	\fILink transmission procedure\fR 
.sp 9p
.RT
.PP
The link transmission procedure shall be in accordance with
[15\ (ii)].
.PP
All standard transmission frames specified in [15] shall be used
(frame with variable length, frame with fixed length and single character).
.PP
The operation mode shall be: master/slave, cyclical polling.
.RT
.sp 1P
.LP
F.1.2.3
	\fIAddressing\fR 
.sp 9p
.RT
.PP
The addresses\ 1 to\ 30 of the\ 256 possible addresses shall be used for 
cyclical polling. 
.PP
The address 255 shall be used for broadcasting (one message to all
nodes).
.RT
.sp 1P
.LP
F.1.2.4
	\fIWindow size\fR 
.sp 9p
.RT
.PP
The window size is fixed to one.
.RT
.sp 1P
.LP
F.1.3
	\fIHigher layers\fR 
.sp 9p
.RT
.PP
Under study.
.bp
.RT
.sp 1P
.LP
F.2
	\fICandidate protocol suite No. 2 (CPS 2)\fR 
.sp 9p
.RT
.PP
Initial application:
.PP
Alarm surveillance, performance monitoring, testing commands and
response, and configuration control of NEs including cross\(hyconnect equipment, 
can be applied to both NEs found in reasonably large numbers in the telephone 
network (e.g., muldex, line transmission terminal) and to high capability 
NEs found in limited numbers in the telecommunications network (e.g. 
cross\(hyconnect).
.RT
.PP
F.2.1
\fIOSI layer 1\fR 
.sp 9p
.RT
.PP
F.2.1.1
\fIConfiguration\fR :  | us.
.PP
F.2.1.2
\fILine speed\fR :  |  Mbit/s.
.PP
F.2.1.3
\fIMedium\fR :  | creened pair.
.PP
F.2.1.4
\fIElectrical requirement\fR :  | ecommendation\ V.11 interface with pulse 
transformer. 
.PP
F.2.1.5
\fILine code\fR :  | MI.
.sp 2P
.LP
F.2.2
	\fIOSI layer 2\fR 
.sp 1P
.RT
.sp 1P
.LP
F.2.2.1
	\fIFrame format\fR 
.sp 9p
.RT
.PP
Frame components:
.RT
.LP
	\(em
	flag,
.LP
	\(em
	destination address: 2 octets,
.LP
	\(em
	source address: 2 octets,
.LP
	\(em
	control: 1 octet,
.LP
	\(em
	logical link control (LLC) data: variable length (maximum   512 octets),
.LP
	\(em
	frame check sequence: CRC 16,
.LP
	\(em
	flag.
.sp 1P
.LP
F.2.2.2
	\fIMedia access control\fR 
.sp 9p
.RT
.PP
The media access control discipline known as carrier sense
multiple access (CSMA) is used [12,\ 18].
.RT
.sp 1P
.LP
F.2.2.3
	\fILogical link control layer\fR 
.sp 9p
.RT
.PP
Acknowledged connectionless mode protocol specification to be
specified in [11,\ 17] is used.
.RT
.sp 1P
.LP
F.2.3
	\fIUpper layers\fR 
.sp 9p
.RT
.PP
Under study.
.RT
.sp 1P
.LP
F.3
	\fICandidate protocol suite No. 3 (CPS 3)\fR 
.sp 9p
.RT
.PP
Initial application:
.PP
Alarm surveillance, performance monitoring, and configuration control of 
NEs found in reasonably large numbers in the telecommunications network 
(e.g. muldex, line transmission terminals).
.RT
.LP
F.3.1
	\fIOSI layer 1\fR 
.sp 1P
.RT
.sp 2P
.LP
F.3.1.1
	\fIPhysical characteristics\fR 
.sp 1P
.RT
.sp 1P
.LP
F.3.1.1.1\ \ \fIConfiguration\fR 
.sp 9p
.RT
.PP
Serial bus operation in accordance with [14] (ring
configuration under study).
.PP
Use of full or half\(hyduplex operation shall be determined by the
Administration.
.bp
.RT
.sp 1P
.LP
F.3.1.1.2\ \ \fITransmission pairs\fR 
.sp 9p
.RT
.PP
Two screened balanced pairs, one pair for each direction of
transmission.
.PP
\fINote\fR \ \(em\ Two Administrations have proposed using each of the 
pairs in half\(hyduplex mode to provide additional bus security without 
additional wiring. Certain additional requirements relating to bus occupancy 
may then be necessary for correct operation in this mode. 
.RT
.sp 1P
.LP
F.3.1.1.3\ \ 
\fIBus security\fR 
.sp 9p
.RT
.PP
Where additional bus security is required, bus duplication or
output driver protection resistors may be considered.
.PP
\fINote\fR \ \(em\ Where duplicated buses are employed, no deliberate
transmission should take place on both buses at the same time, and the
functioning of one bus shall not be prejudiced by continuous noise or
unintentional transmissions on the other.
.RT
.sp 1P
.LP
F.3.1.1.4\ \ \fIConnector\fR 
.sp 9p
.RT
.PP
The Administration shall specify the connector type.
.RT
.sp 2P
.LP
F.3.1.2
	\fIElectrical characteristics\fR 
.sp 1P
.RT
.sp 1P
.LP
F.3.1.2.1\ \ \fIStatic and dynamic characteristics\fR 
.sp 9p
.RT
.PP
Static and dynamic characteristics of each bus connection shall be in accordance 
with\ [14]. 
.RT
.sp 1P
.LP
F.3.1.2.2\ \ \fIBus termination\fR 
.sp 9p
.RT
.PP
Each bus end shall be terminated by resistors (120\ ohms +10%, \(em0%) 
in accordance with\ [14]. 
.RT
.sp 1P
.LP
F.3.1.2.3\ \ \fILoad connection\fR 
.sp 9p
.RT
.PP
Each receiver shall present a maximum of one unit load, as defined in [14], 
to the bus. The number of load connections is limited to 32. 
.RT
.sp 1P
.LP
F.3.1.2.4\ \ \fIBit rate\fR 
.sp 9p
.RT
.PP
The bit rate shall be 19.2 or 64 kbit/s. A bit rate of 128\ kbit/s may 
be necessary in some applications. The bit rate tolerance shall be 
\(+-\ 1%.
.RT
.sp 1P
.LP
F.3.1.2.5\ \ \fITurn\(hyoff time\fR 
.sp 9p
.RT
.PP
A transmitting station shall put its generator in the high
impedance state within 1\ ms from the end of the last bit of the final 
closing flag. 
.PP
\fINote\fR \ \(em\ The need to reduce this time for bit rates above 19.2\ 
kbitB/Fs is under study. 
.RT
.sp 1P
.LP
F.3.1.2.6\ \ \fIPreamble\fR 
.sp 9p
.RT
.PP
Following the enabling of the generator, an implementation
dependant preamble of no more than 4\ bit times is allowed. No assumption 
as to the state of the bus during this preamble is allowed. 
.RT
.sp 1P
.LP
F.3.1.3
	\fILine code\fR 
.sp 9p
.RT
.PP
The line code shall be NRZ1.
.PP
Clock extraction by the remaining station is assumed.
.RT
.sp 1P
.LP
F.3.1.3.1\ \ \fIPrinciple\fR 
.sp 9p
.RT
.PP
Each transition [14] shall represent a ZERO, and no transition
shall represent a ONE\ bit.
.RT
.sp 1P
.LP
F.3.1.3.2\ \ \fILock\(hyin process\fR 
.sp 9p
.RT
.PP
For clock extraction, a lock\(hyin sequence of either one octet of
ZEROES or one or two flags in accordance with [6], shall be sent immediately
prior to the beginning of the opening flag of the frame to be transmitted 
and immediately following the preamble of \(sc\ F.3.1.2.6 (if implemented). 
.bp
.RT
.sp 1P
.LP
F.3.1.4
	\fIExtended mode\fR 
.sp 9p
.RT
.PP
Where an extended mode capability is required (e.g., using a modem) the 
requirements of \(sc\(sc\ F.3.1.1 
to\ F.3.1.3 shall apply with the following
exceptions:
.RT
.sp 1P
.LP
F.3.1.4.1\ \ \fIConfiguration\ \(em\ full duplex\fR 
.sp 9p
.RT
.sp 1P
.LP
F.3.1.4.2\ \ \fIConnector\fR 
.sp 9p
.RT
.PP
The connector shall conform to [16]. Appropriate signal leads are to be 
provided for modem control in accordance with Recommendation\ V.24 
[2],\ [22]. See Table\ F\(hy1/G.771.
.RT
.sp 1P
.LP
F.3.1.4.3\ \ \fIElectrical requirements\fR 
.sp 9p
.RT
.PP
Data set control leads shall conform to Recommendation\ V.24
[2],\ [22].
.RT
.sp 1P
.LP
F.3.1.4.4\ \ \fILine code\fR 
.sp 9p
.RT
.PP
NRZ line code shall be employed. A separate clock distribution
shall be provided.
.RT
.sp 1P
.LP
F.3.1.4.5\ \ \fISpeed\fR 
.sp 9p
.RT
.PP
The bit rate shall be 9.6 or 64\ kbit/s. Lower speed, e.g. 1.2, 2.4 and 
4.8 kbit/s, may be necessary in some applications. 
.RT
.sp 1P
.LP
F.3.2
	\fIOSI layer 2\fR 
.sp 9p
.RT
.PP
The data link protocol is synchronous HDLC type.
.RT
.sp 1P
.LP
F.3.2.1
	\fIHDLC frame structure\fR 
.sp 9p
.RT
.PP
The HDLC frame structure shall conform to [6] (frame
structure).
.RT
.sp 1P
.LP
F.3.2.1.1\ \ \fIAddressing field\fR 
.sp 9p
.RT
.PP
The addressing field shall be one octet.
.RT
.sp 1P
.LP
F.3.2.1.2\ \ \fIInformation field\fR 
.sp 9p
.RT
.PP
The information field in any HDLC frame shall be an integral number of octets.
.PP
Information field octets shall be sent with the least significant bit  first.
.PP
Maximum information field lengths of 128 and 256 octets shall be
supported.
.PP
A maximum information field length of 512 octets may be necessary in some 
applications. 
.RT
.sp 1P
.LP
F.3.2.2
	\fIAddressing\fR 
.sp 9p
.RT
.PP
The secondary station shall be capable of being assigned any
address in the range\ 1 to 254.
.RT
.sp 1P
.LP
F.3.2.2.1\ \ \fIAll\(hystation address\fR 
.sp 9p
.RT
.PP
The address field pattern \*Q11111111\*U is defined as the all\(hystation 
address. 
.RT
.sp 1P
.LP
F.3.2.2.2\ \ \fINo station address\fR 
.sp 9p
.RT
.PP
The address field pattern \*Q00000000\*U is defined as the no\(hystation 
address. 
.PP
The no\(hystation address shall never be assigned to a secondary
station.
.RT
.sp 1P
.LP
F.3.2.2.3\ \ \fIGroup address\fR 
.sp 9p
.RT
.PP
Not used.
.RT
.sp 1P
.LP
F.3.2.3
	\fIHDLC procedure\fR 
.sp 9p
.RT
.PP
The HDLC procedure is defined by [7].
.bp
.RT
.sp 1P
.LP
F.3.2.3.1\ \ \fICommands and responses\fR 
.sp 9p
.RT
.PP
The following HDLC commands and responses must be
supported:
.RT
.LP
	a)
	commands:
.LP
	\(em
	SNRM: set normal response mode;
.LP
	\(em
	DISC: disconnect;
.LP
	b)
	commands or responses:
.LP
	\(em
	I: information;
.LP
	\(em
	RR: receive ready;
.LP
	\(em
	RNR: receive not ready;
.LP
	c)
	responses:
.LP
	\(em
	FRMR: frame reject;
.LP
	\(em
	UA: unnumbered acknowledgement;
.LP
	\(em
	DM: disconnected mode.
.sp 1P
.LP
F.3.2.3.2\ \ \fIModes\fR 
.sp 9p
.RT
.PP
Two modes are selected:
.RT
.LP
	\(em
	one operational mode: normal response mode (NRM);
.LP
	\(em
	one non\(hyoperational mode: normal disconnected mode
(NDM).
.sp 1P
.LP
F.3.2.4
	\fIClass of procedure\fR 
.sp 9p
.RT
.PP
The Unbalanced operation Normal response mode Class (UNC) as
defined by [9] shall be implemented.
.RT
.sp 1P
.LP
F.3.2.4.1\ \ \fIHDLC optional functions\fR 
.sp 9p
.RT
.PP
The following HDLC optional functions shall be
implemented:
.RT
.LP
	a)
	unnumbered information (option No.\ 4):
.LP
	\(em
	command UI;
.LP
	\(em
	response UI;
.LP
	b)
	data link test (option No.\ 12):
.LP
	\(em
	command TEST;
.LP
	\(em
	response TEST.
.sp 2P
.LP
F.3.2.5
	\fIOther parameters of OSI layer 2\fR 
.sp 1P
.RT
.sp 1P
.LP
F.3.2.5.1\ \ \fIWindow size\fR 
.sp 9p
.RT
.PP
The window size is fixed to\ 1.
.RT
.sp 1P
.LP
3.2.5.2\ \ 
\fIWaiting\(hytime before a repetition\fR 
.sp 9p
.RT
.PP
In the case of no\(hyreply or lost\(hyreply, the primary station shall
provide a waiting\(hytime function.
.PP
The waiting\(hytime before a repetition has to be greater than the
duration of the longest frame to be sent by the primary station, added 
with the response\(hytime of the secondary station and the duration of 
the longest frame to be sent by the secondary station. 
.RT
.sp 1P
.LP
F.3.2.5.3\ \ \fINumber of repetitions\fR 
.sp 9p
.RT
.PP
In the situation of \(sc\ F.3.2.5.2, the maximum number of repetitions 
before detecting a no\(hyreply or a lost\(hyreply condition is fixed at\ 
5 
(6\ requests).
.RT
.sp 1P
.LP
F.3.2.5.4\ \ \fIResponse time\fR 
.sp 9p
.RT
.PP
The secondary station shall commence the opening flag of its
response not later than 5\ ms after the end of the closing flag of the frame
sent from the primary station.
.PP
\fINote\fR \ \(em\ The need to reduce this time for bit rates above 19.2\ 
kbitB/Fs is under study. 
.bp
.RT
.sp 1P
.LP
F.3.3
	\fIHigher layers\fR 
.sp 9p
.RT
.PP
Under study.
.RT
.LP
.sp 1
.ce
\fBH.T. [T1.771]\fR 
.ce
TABLE\ F\(hy1/G.771
.ce
\fBPin description of 24\(hypin connector [16]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(24p) | cw(24p) | cw(90p) | cw(30p) .
Pin	V.24  circuit	Description	Notes
_
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 1	101	Protective ground	1
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
13	102	Signal ground	
_
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 2	103	Send data A\(hywire	
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
14	103	Send data B\(hywire	
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
11	104	Receive Data A\(hywire	
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
23	104	Receive Data B\(hywire	
_
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 3	105	Request to Send A\(hywire	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
15	105	Request to Send B\(hywire	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 7	106	Clear to Send A\(hywire	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
19	106	Clear to Send B\(hywire	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 8	107	Data Mode A\(hywire	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
20	107	Data Mode B\(hywire	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 9	109	Receiver Ready A\(hywire	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
21	109	Receiver Ready B\(hywire	2
_
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 6	114	 {
Send Timing A\(hywire
(DCE to DTE)
 }	
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
18	114	 {
Send Timing B\(hywire
(DCE to DTE)
 }	
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
10	115	 {
Receive Timing A\(hywire
(DCE to DTE)
 }	
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
22	115	 {
Receive Timing B\(hywire
(DCE to DTE)
 }
.TE
.LP
\fINote\ 1\fR
\ \(em
Equipment: removable strap to frame ground.
Cable: connected to shield.
.LP
\fINote\ 2\fR
\ \(em\ These circuits are optional for connection to an embedded
operations channel or modem and are not used for connections to a
multipoint bus.
.LP
\fINote\ 3\fR
\ \(em\ Circuits are grouped by function: ground, data, control and
timing.
Provision should be made at each interface point on a multipoint bus for the
continuation of the interface to the next network element.
Provision shall be made for the termination of the lines in their
characteristics impedance (typically, 120\ ohms, resistive), should the
equipment be at one of a multipoint bus.
For further information, see [2], [16], [22], [23].
.nr PS 9
.RT
.ad r
\fBTable F\(hy1/G.771 [T1.771], p.  \fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
F.4
	\fICandidate protocol suite No. 4 (CPS 4)\fR 
.sp 1P
.RT
.PP
Initial application:
.PP
Alarm surveillance, performance monitoring, testing on specific NEs
found in limited numbers in the telecommunications network (e.g. muldex, 
line transmission equipment). 
.RT
.sp 1P
.LP
F.4.1
	\fILayer 1\fR \v'3p'
.sp 9p
.RT
.LP
	\(em
	Electrical characteristics in accordance with
Recommendations\ V.24 and\ V.28\ [20];
.LP
	\(em
	Configuration: star;
.LP
	\(em
	Physical connection: ISO 2110 (25\ pin) (see
Table\ F\(hy2/G.771);
.LP
	\(em
	Transmission mode: duplex, interface type D;
.LP
	\(em
	Operating speed: 1200, 2400, 4800 and 9600 bit/s (user
option);
.LP
	\(em
	Shield: ground strap to frame (user option).
.ce
\fBH.T. [T2.771]\fR 
.ce
TABLE\ F\(hy2/G.771
.ce
\fBISO 2110 pin description\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(24p) | cw(24p) | cw(90p) | cw(30p) .
Pin	V.24  circuit	Description	Notes
_
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 1	101 |  	Protective ground	1
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 7	102 |  	Signal ground	2
_
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 2	103 |  	Transmitted data	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 3	104 |  	Received data	2
_
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 4	105 |  	Request to Send	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 5	106 |  	Clear to Send	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 6	107 |  	Data Set Ready	2
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
20	108.2	Data Terminal Ready	3
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
22	125 |  	Ring indicator	3
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
\ 8	109 |  	Received Line Signal Detector	2
_
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
24	113 |  	 {
Transmitter Signal Element Timing
(DTE to DCE)
 }	4
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
15	114 |  	 {
Transmitter Signal Element Timing
(DCE to DTE)
 }	5
.T&
cw(24p) | cw(24p) | lw(90p) | cw(30p) .
17	115 |  	 {
Receiver Signal Element Timing
(DCE to DTE)
 }	5
.TE
.LP
\fINote\ 1\fR
\ \(em
Equipment: removable strap to frame ground.
Cable: connected to shield.
.LP
\fINote\ 2\fR
\ \(em\ Basic interchange circuits, all systems.
.LP
\fINote\ 3\fR
\ \(em\ Additional interchange circuits required for switched service.
.LP
\fINote\ 4\fR
\ \(em\ Circuit DA (CCITT 113) is not used in OS/NE interfaces.
.LP
\fINote\ 5\fR
\ \(em\ Additional interchange circuits required for synchronous channel.
.LP
\fINote\ 6\fR
\ \(em\ Duplex, interface type D.
Circuits are grouped by function: ground, data, control and timing.
For further information, see [2], [3], [5], [19].
.nr PS 9
.RT
.ad r
\fBTableau F\(hy2/G.771 [T2.771], p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
F.4.2
	\fILayer 2\fR 
.sp 9p
.RT
.PP
It is mandatory that the data link layer conform to LAPB as defined in 
Recommendation\ X.25 [4]. In addition, provision shall be made for connection 
between data terminal equipments (OSs and NEs) without an intervening packet 
switched network. The interface shall conform to\ [8].
.PP
The link layer specification that follows applies to all cases.
.RT
.sp 1P
.LP
F.4.2.1
	\fIEquipment type during link set\(hyup and reset\fR 
.sp 9p
.RT
.PP
When a packet switched network is used to connect the NE and OS,
they each are designated Data Terminal Equipment (DTE) and the network acts
as a Data Circuit\(hyTerminating Equipment (DCE). When a dedicated or dial\(hyup 
link is provided, other means must be used to supply the DCE role.
.PP
At level\ 1, the modems will provide the DCE interface, supplying bit synchronization. 
.PP
At the link level, the procedures specified in [8] are followed. The NE 
or OS must be able to start the set\(hyup or reset of the link (a DCE function 
in Recommendation\ X.25) as well as to respond to a start from the connecting 
equipment (a DTE function in Recommendation\ X.25). In addition, provision 
must be made for assignment of the A/B addresses. This mandatory option 
is to be 
field\(hysettable and stored in non\(hyvolatile memory. Equipment which 
meets this 
requirement is compatible with connection to either a DCE or remote DTE.
.RT
.sp 1P
.LP
F.4.2.2
	\fIWindow\fR 
.sp 9p
.RT
.PP
Modulo 8 operation shall be used. The window for unacknowledged
frames is to be optional between 1 and 7 frames. Typical values are\ 7
and\ 2.
.RT
.sp 1P
.LP
F.4.2.3
	\fIUser information\fR 
.sp 9p
.RT
.PP
The user information is to be arranged in an integral number of
octets.
.PP
The maximum length of the user information shall be user settable,
consistent with the range of values for the N1 parameter as shown in
Table\ F\(hy3/G.771. Maximum information field lengths that shall be supported 
are 131 and 259 octets with 515 octets optional. These values provide for 
three 
packet header octets and maximum length of packet data units of 128, 256 and
512 octets respectively.
.RT
.sp 1P
.LP
F.4.2.4
	\fIOther frame parameters\fR 
.sp 9p
.RT
.PP
Certain other frame parameters shall be set by the user to be
consistent with the bit rate, frame size and characteristics of the connecting 
network. The NE design should be sufficiently flexible to accommodate parameter 
sets for diverse networks, both as order options and later reconfigurations. 
The range of parameters is shown in Table\ F\(hy3/G.771. These options, 
like those of the physical layer, are to be set at installation, changeable 
by the user, and non\(hyvolatile. 
.RT
.sp 1P
.LP
F.4.3
	\fIOther layers\fR 
.sp 9p
.RT
.PP
No layer 3 is planned for this suite.
.PP
Layers 4\(hy7 are under study.
.RT
.sp 1P
.LP
F.5
	\fICandidate protocol suite No.\ 5 (CPS\ 5)\fR 
.sp 9p
.RT
.PP
Initial application:
.PP
All management of high capability NEs found in limited numbers in the telecommunications 
network (e.g. digital cross\(hyconnect). 
.RT
.sp 1P
.LP
F.5.1
	\fILayer 1\fR \v'3p'
.sp 9p
.RT
.LP
	\(em
	 Electrical characteristics in accordance with Recommendations V.24 and 
V.28 [20]; 
.LP
	\(em
	Configuration: star;
.LP
	\(em
	Physical connection: ISO 2110 (25 pin) (see Table
F\(hy2/G.771);
.LP
	\(em
	Transmission mode: duplex, interface type\ D;
.LP
	\(em
	Operating speed: 1200, 2400, 4800 and 9600 bit/s (user
option);
.LP
	\(em
	Shield: ground strap to frame (user option).
.bp
.ce
\fBH.T. [T3.771]\fR 
.ce
TABLE\ F\(hy3/G.771
.ce
\fBLAPB data link layer attributes\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(204p) .
LAPB Protocol  Octet aligned
.TE
.TS
center box ;
cw(114p) | cw(30p) | cw(30p) | cw(30p) .
Single link procedure (SLP)	Range	Default values  (Note 1)	Units
_
.T&
lw(114p) | lw(30p) | cw(30p) | lw(30p) .
K\  \(em I\(hyFrames window:	1 to 7	\ \ \ 7	
.T&
lw(114p) | lw(30p) | cw(30p) | lw(30p) .
 {
T1 \(em Waiting acknowledgement
\ \ \ (Retry) timer:
 }	2 to 20	\ \ \ 3	seconds
.T&
lw(114p) | lw(30p) | cw(30p) | lw(30p) .
T2 \(em Response delay timer	0.3		seconds
.T&
lw(114p) | lw(30p) | cw(30p) | lw(30p) .
T3 \(em Disconnect time	Note 2		
.T&
lw(114p) | lw(30p) | cw(30p) | lw(30p) .
T4 \(em No activity timer	4 to 120	\ \ 20	seconds
.T&
lw(114p) | lw(30p) | cw(30p) | lw(30p) .
 {
N1 \(em Bits per I\(hyFrame, excluding flags
 }	1080, 2104	1080	bits
.T&
lw(114p) | lw(30p) | cw(30p) | lw(30p) .
N2 \(em Retransmission count	2 to 16	\ \ \ 7	
.T&
lw(114p) | lw(30p) | cw(30p) | lw(30p) .
A/B address assignment	Selectable by the user
.TE
.LP
\fINote\ 1\fR
\ \(em\ The default values shall be part of a vendor's offering. That is,
unless otherwise specified by the user, the default parameters shall be the
initial values supplied. They can be subsequently changed by the user within
the specified range.
.LP
\fINote\ 2\fR
\ \(em\ The value of time T3, the disconnect timer, is not critical for
successful interworking of OSs and NEs. Therefore no value is
specified.
.nr PS 9
.RT
.ad r
\fBTableau F\(hy3/G.771 [T3.771], p. 7\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.sp 2
.sp 1P
.LP
F.5.2
	\fILayer 2\fR 
.sp 9p
.RT
.PP
It is mandatory that the data link layer conform to LAPB as defined in 
Recommendation\ X.25\ [4]. In addition, provision shall be made for 
connection between data terminal equipments (OSs and NEs) without an
intervening packet switched network. The interface shall conform to [8].
.PP
The link layer specification that follow applies to all cases.
.RT
.sp 1P
.LP
F.5.2.1
	\fIEquipment type during link set\(hyup and reset\fR 
.sp 9p
.RT
.PP
When a packet switched network is used to connect the NE and OS,
they each are designated data terminal equipment (DTE) and the network acts
as a data circuit\(hyterminating equipment (DCE). When a dedicated or dial\(hyup 
link is provided, other means must be used to supply the DCE role.
.PP
At level\ 1, the modems will provide the DCE interface, supplying bit synchronization. 
.PP
At the link level, the procedures specified in [8] are followed. The NE 
or OS must be able to start the set\(hyup or reset of the link (a DCE function 
in Recommendation\ X.25) as well as to respond to a start from the connecting 
equipment (a DTE function in Recommendation\ X.25). In addition, provision 
must be made for assignment of the AB/FB addresses. This mandatory option 
is to be 
field\(hysettable and stored in non\(hyvolatile memory. Equipment which 
meets this requirement is compatible with connection to either a DCE or 
remote DTE. 
.bp
.RT
.sp 1P
.LP
F.5.2.2
	\fIWindow\fR 
.sp 9p
.RT
.PP
Modulo 8 operation shall be used. The window for unacknowledged
frames is to be optional between\ 1 and\ 7 frames. Typical values are\ 7
and\ 2.
.RT
.sp 1P
.LP
F.5.2.3
	\fIUser information\fR 
.sp 9p
.RT
.PP
The user information is to be arranged in an integral number of
octets. In other words, the data is to be structured in\ 8 bit bytes.
.PP
The maximum length of the user information shall be user settable,
consistent with the range of values for the N1 parameter as shown in
Table\ F\(hy3/G.771. Maximum information field lengths that shall be supported 
are 131 and 259 octets with 515 octets optional. These values provide for 
three 
packet header octets and maximum length of packet data units of 128, 256 and
512 octets, respectively.
.RT
.sp 1P
.LP
F.5.2.4
	\fIOther frame parameters\fR 
.sp 9p
.RT
.PP
Certain other frame parameters shall be set by the user to be
consistent with the bit rate, frame size and characteristics of the connecting 
network. The NE design should be sufficiently flexible to accommodate parameter 
sets for diverse networks, both as order options and later reconfigurations. 
The range of parameters is shown in Table\ F\(hy3/G.771. These options, 
like those of the physical layer, are to be set at installation, changeable 
by the user, and non\(hyvolatile. 
.RT
.sp 1P
.LP
F.5.3
	\fILayer 3\fR 
.sp 9p
.RT
.PP
It is mandatory that the packet layer conform to
Recommendation\ X.25. In addition the packet layer must provide for connection 
of data terminal equipment (OSs and NEs) without an intervening packet 
network; the required interface for this purpose conforms to [10]. In addition, 
the 
provisions of [13] shall apply.
.PP
The attributes which must be supported are summarized in
Table\ F\(hy4/G.771. Note in particular that this table shows the different
attributes needed to support PVCs (the X.25/PVC procedures) and SVCs (the
X.25/SVC procedures).
.RT
.sp 1P
.LP
F.5.3.1
	\fIEquipment type during restart\fR 
.sp 9p
.RT
.PP
When the packet level X.25 interface is used, automatic selection of the 
DCE/DTE role during restart is required, as specified in\ [10]. 
.RT
.sp 1P
.LP
F.5.3.2
	\fIOther features and parameters\fR 
.sp 9p
.RT
.PP
The packet layer attributes are summarized in Table\ F\(hy4/G.771.
.RT
.sp 1P
.LP
F.5.4
	\fIHigher layers\fR 
.sp 9p
.RT
.PP
Under study.
.RT
.sp 1P
.LP
F.6
	\fICandidate protocol suite No. 6 (CPS 6)\fR 
.sp 9p
.RT
.PP
Initial application:
.PP
Alarm surveillance, performance monitoring and configuration control of 
NEs found in reasonably large numbers in the telecommunications network 
(e.g. muldex, line transmission terminal).
.RT
.sp 2P
.LP
F.6.1
	\fIInterface characteristics\fR 
.sp 1P
.RT
.sp 1P
.LP
F.6.1.1
	\fIGeneral characteristics\fR \v'3p'
.sp 9p
.RT
.LP
	\(em
	Network topology: \*Qloop\*U (a variety of a ring chain
configuration);
.LP
	\(em
	Serial data transmission;
.LP
	\(em
	Master\(hyslave principle;
.LP
	\(em
	Maximum number of slaves: 30;
.LP
	\(em
	Transmission medium: one balanced screened pair (with the
possibility of providing bypasses of faulty sections of the \*Qloop\*U and
slaves);
.LP
	\(em
	Maximum connection length between two connected slaves:
1000\ m.
.bp
.ce
\fBH.T. [T4.771]\fR 
.ce
TABLE\ F\(hy4/G.771
.ce
\fBX.25 packet layer attributes\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(120p) | cw(36p) | cw(36p) | cw(36p) .
Attributes	Range  (Notes 1, 2)	Default  values  (Note 3)	Units
_
.T&
lw(120p) | lw(36p) | lw(36p) | lw(36p) .
 {
\fIPermanent virtual circuits\fR
 }			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Packet size	128, 256,  512 optional	\ 128	octets
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Window size	1\(hy7	\ \ \ 2	
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Interrupt packets	optional		
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
 {
\fISwitched virtual circuits\fR
 }			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
 {
\ Flow control parameter negotiation
 }			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Packet size	128, 256,  512 optional	\ 128	octets
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Window size	1\(hy7	\ \ \ 2	
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
 {
\ Throughput class negotiation
 }			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Bit rate	1200, 2400,  4800, 9600	2400	bit/s
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
 {
\ Expedited data negotiation
\ Closed user group
 }			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ Closed user group selection			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Basic format	2		decimal digits
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Fast select	128		octets
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ \ Fast select acceptance			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ Hunt group			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
 {
\ Transit delay selection and indication
 }			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ Calling address extension			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ Called address extension			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
 {
\ Minimum throughput class negotiation
 }			
.T&
lw(120p) | lw(36p) | cw(36p) | lw(36p) .
\ End\(hyto\(hyend transit delay negotiation
.TE
.LP
\fINote\ 1\fR
\ \(em\ The ranges specified for negotiated parameters in no way affect
the normal negotiation rules specified in the international standards.
.LP
\fINote\ 2\fR
\ \(em\ The attributes which are not marked optional are mandatory.
.LP
\fINote\ 3\fR
\ \(em\ The default values shall be part of a vendor's offering. That is,
unless otherwise specified by the user, the default parameters shall be the
initial values supplied. They can be subsequently changed by the user
within the specified range.
.nr PS 9
.RT
.ad r
\fBTableau F\(hy4/G.771 [T4.771], p. 8\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
F.6.1.2
	\fILayer 1 of the ISO\(hyOSI reference model\fR  | physical layer)
\v'3p'
.sp 9p
.RT
.LP
	\(em
	Electrical characteristics in accordance with
Recommendations\ V.11 and V.24 [1], [2], [21];
.LP
	\(em
	Transmission method: asynchronous;
.LP
	\(em
	Mode of operation of the slave: duplex;
.LP
	\(em
	Transmission rate: \(= 19 | 00 bit/s.
.bp
.PP
F.6.1.3
Further layers are under study.
.sp 9p
.RT
.ce
\fBH.T. [T5.771]\fR 
.ce
TABLE\ F\(hy5/G.771
.ce
\fBCandidate protocol selection attribute values\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Attribute	CPS 1	CPS 2	CPS 3	CPS 4	CPS 5	CPS 6
_
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
\fILayer 1\fR						
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Configuration	B	B	B,R | ua\d\u)\d	S	S	R
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
 {
No. of ports per configuration
 }	M	VL	M	M	M	M
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Physical medium	SP	SP	SP	SP	SP	SP
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Transmission mode	AS\(hyHD	S\(hyFD	S\(hyHD,FD	S\(hyFD	S\(hyFD	AS\(hyHD
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Operating speed (bit/s)	19 | 00	1 | 00 | 00	\ 19 | 00 \ 64 | 00  128 | 00	1200 9600	1200 9600	\(= 19 | 00
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Communication distance	M	M	M(L)	M(L)	M(L)	M
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Communication environment	IB	IB	IB(OB)	IB(OB)	IB(OB)	IB
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Availability | ua\d\u)\d						
_
.T&
lw(84p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) .
\fILayer 2\fR						
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Data link connection	CO	CL	CO	CO	CO	CO
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Data link initiator	M	AP	M	AP	AP	M
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Data link address size	M	VL	VL	S	S	\ua\d\u)\d
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Receipt confirmation	Y	Y	Y	Y	Y	Y
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Max. frame size	S	M	S,M	S,M	S,M	S
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Max. frame frequency per port	H	H	H	H	H	M
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Max. frame transmit delay	M	S	M	S,M	S,M	S
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Error detection	P+CS8	CRC16	CRC16	CRC16	CRC16	CRC
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Hamming distance	4					
.T&
lw(84p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Error recovery	R	R	R	R	R	R
_
.T&
lw(84p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) .
\fILayer 3\fR						
.T&
lw(84p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) .
LCN network size					VL	
.T&
lw(84p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) .
Routing					Y	
.T&
lw(84p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) .
(Un) packing					Y	
.T&
lw(84p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) .
Connections					P,SW	
.T&
lw(84p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) .
Priority					Y	
_
Higher layers | ua\d\u)\d
.TE
.LP
\ua\d\u)\d\ Under study.
.LP
\fINote\fR
\ \(em\ An explanation of the abbreviations used in this Annex is given
in Annex\ E.
.nr PS 9
.RT
.ad r
\fBTable F.5/G.771 [T5.771], p.  \fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
	\fBReferences\fR 
.sp 1P
.RT
.LP
[1]
	CCITT Recommendation \fIElectrical characteristics for balanced\fR 
\fIdouble\(hycurrent interchange circuits for general use with integrated 
circuit\fR \fIequipment in the field of data communication\fR , Vol.\ VIII, 
Rec.\ V.11. 
.LP
[2]
	CCITT Recommendation \fIList of definitions for interchange circuits\fR 
\fIbetween data terminal equipment and data circuit\(hyterminating equipment\fR 
, 
Vol.\ VIII, Rec.\ V.24.
.LP
[3]
	CCITT Recommendation \fIElectrical characteristics for unbalanced\fR 
\fIdouble\(hycurrent interchange circuits\fR , Vol.\ VIII, Rec.\ V.28.
.LP
[4]
	 CCITT Recommendation \fIInterface between Data Terminal Equipment (DTE)\fR 
\fIand Data Circuit\(hyTerminating Equipment (DCE) for terminals operating 
in the\fR \fIpacket mode and connected to public data networks by dedicated 
circuit\fR , 
Vol.\ VIII, Rec.\ X.25.
.LP
[5]
	 ISO 2110 \fIData communications \(em 25\(hypin DTE/DCE interface connector 
and\fR \fIpin assignments\fR . 
.LP
[6]
	ISO 3309 \fIData communications \(em High\(hylevel data link control\fR 
\fIprocedures \(em Frame structure\fR .
.LP
[7]
	ISO 4335 \fIData communications \(em High\(hylevel data link control\fR 
\fIprocedures \(em Consolidation of elements of procedures\fR .
.LP
[8]
	ISO 7776 \fIData communications \(em High\(hylevel data link control\fR 
\fIprocedures \(em Description of the X.25 LAPB\(hycompatible DTE data link\fR 
\fIprocedures\fR .
.LP
[9]
	ISO 7809 \fIData communications \(em High\(hylevel data link control\fR 
\fIprocedures \(em Consolidation of classes of procedures\fR .
.LP
[10]
	 ISO 8208 \fIInformation Processing Systems \(em X.25 packet level protocol\fR 
\fIfor data terminal equipment\fR . 
.LP
[11]
	ISO 8802.2 \fIInformation Processing Systems \(em Local area networks\fR 
\fI\(em Part 2: Logical link control\fR .
.LP
[12]
	ISO 8802.3 \fIInformation Processing Systems \(em Local area networks\fR 
\fI\(em Part 3: Carrier sense multiple access with collision detection\fR .
.LP
[13]
	ISO 8878 \fIData communications \(em Use of X.25 to provide the OSI\fR 
\fIconnection\(hymode network service\fR .
.LP
[14]
	ISO DIS 8482 \fIData communications \(em Twisted pair multipoint\fR 
\fIinterconnections\fR .
Compatible with Rec. V.11 and Reference 23.
.LP
[15]
	IEC TC 57 Part\ 5
.LP
	(i)
	IEC TC 57 Part 5\(hy1. Format FT 1.2
.LP
	(ii)
	IEC TC 57 Part 5\(hy2.
.LP
[16]
	IEEE STD 488 \fIStandard digital interface for programmable\fR 
\fIinstrumentation\fR .
.LP
[17]
	IEEE STD 802.2 \fILocal area networks \(em Logical link control\fR .
.LP
[18]
	IEEE STD 802.3 \fILocal area networks \(em Carrier sense multiple\fR 
\fIaccess/collision detection\fR .
.LP
[19]
	EIA\(hy232\(hyC \fIInterface between Data Terminal Equipment and Data\fR 
\fICommunications Equipment employing serial binary data interchange\fR .
.LP
[20]
	EIA\(hy232\(hyD \fIInterface between Data Terminal Equipment and\fR 
\fIData Circuit\(hyTerminating Equipment employing serial binary data interchange\fR 
. 
.LP
[21]
	EIA\(hy422 \fIElectrical characteristics of balanced voltage digital\fR 
\fIinterface circuits\fR .
.LP
[22]
	 EIA\(hy449 \fIGeneral purpose 37\(hyposition and 9\(hyposition interface 
for\fR 
\fIData Terminal Equipment and Data Circuit\(hyTerminating Equipment employing\fR 
\fIserial binary data interchange\fR .
.LP
[23]
	 EIA\(hy485 \fIElectrical characteristics of generators and receivers 
for\fR \fIuse in balanced digital multipoint systems\fR . 
.bp
.sp 2P
.LP
\fBRecommendation\ G.772\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fBDIGITAL\ PROTECTED\ MONITORING\ POINTS\fR 
.EF '%	Fascicle\ III.4\ \(em\ Rec.\ G.772''
.OF '''Fascicle\ III.4\ \(em\ Rec.\ G.772	%'
.ce 0
.sp 1P
.ce 1000
\fR \fI(Melbourne, 1988)\fR 
.sp 9p
.RT
.ce 0
.sp 1P
.PP
\fINote\fR \ \(em\ 
The detailed requirements contained in this
Recommendation are applicable to the 2048\ kbit/s hierarchy. The application 
of the principles defined in this Recommendation to the 1544\ kbit/s hierarchy 
is for further study. 
.sp 1P
.RT
.sp 2P
.LP
\fB1\fR 	\fBDefinition\fR 
.sp 1P
.RT
.PP
A \fBprotected monitoring point (PMP)\fR provides a digital
interface at which it is possible to monitor the transmitted signal and 
to make measurements with suitable test equipments\ [1]. 
.RT
.sp 2P
.LP
\fB2\fR 	\fBLocation\fR 
.sp 1P
.RT
.PP
The possible locations for protected monitoring points can
be:
.RT
.LP
	a)
	at the output ports of an equipment;
.LP
	b)
	in the signal path between equipments.
.PP
Some examples are shown in Figure 1/G.772.
.sp 2P
.LP
\fB3\fR 	\fBElectrical characteristics of the \fR \fBprotected\fR 
\fBmonitoring point\fR 
.sp 1P
.RT
.PP
\fINote\fR \ \(em\ The reference for all parameters associated with protected 
monitoring points shall be the relevant output interface as defined in 
Recommendation\ G.703\ [2] (see Figures\ 1/G.772 and 2/G.772).
.RT
.sp 1P
.LP
3.1
	\fIImpedance\fR 
.sp 9p
.RT
.PP
The load impedance presented by the test equipment at the protected monitoring 
point is the nominal impedance for the corresponding transmission 
path interface as defined in Recommendation\ G.703.
.RT
.sp 1P
.LP
3.2
	\fIAttenuation\fR 
.sp 9p
.RT
.PP
The attenuation between the transmission path interface and the
protected monitoring point, when the impedance presented by the test and
measuring equipment connected to the protected monitoring point is equal 
to the nominal impedance for the relevant interface as defined in 
Recommendation\ G.703, shall be \fIA\fR \ \(+-\ 1\ dB for all frequencies 
in the range 2.5% to 150% of the nominal bit rate at the interface (see 
Figure\ 2/G.772). 
.PP
Different values may be necessary at different nominal bit rates.
.PP
The value of \fIA\fR  | s under study.
.PP
The digital signal level presented at the transmission path interface of 
the protected monitoring point shall be as defined in Recommendation\ G.703 
but modified by the characteristics of the interconnecting cable. The 
attenuation of the cable shall be assumed to follow a 
@ sqrt { fIf\fR~ | } @ \ law and the  loss\ \fIX\fR at a frequency equal to half the nominal bit rate is given below:
.RT
.LP
	0 \(= \fIX\fR \(= 3 dB for 64 kbit/s
.LP
	0 \(= \fIX\fR \(= 6 dB for 2 and 8 Mbit/s
.LP
	0 \(= \fIX\fR \(= 12 dB for 34 and 140 Mbit/s.
.PP
\fINote\fR \ \(em\ For a protected monitoring point device at an equipment 
output port, as described in Figure 
1a/G.772, the value of \fIX\fR is 0\ dB.
.bp
.sp 2P
.LP
3.3
	\fIProtection of the PMP device\fR 
.sp 1P
.RT
.PP
3.3.1
The protection of the protected monitoring point device against electrostatic 
discharges shall accord with the requirements of 
Recommendation\ K.21\ [3] and IEC Publication\ 801\(hy2\ [4].
.sp 9p
.RT
.PP
3.3.2
No damage shall result from the application of any load
impedance, including short and open circuits, to the protected monitoring
point.
.PP
3.3.3
The protection against the inadvertent application of voltages to the protected 
monitoring point is under study. 
.sp 2P
.LP
\fB4\fR 	\fBElectrical characteristics of the transmission path interface\fR 
.sp 1P
.RT
.PP
\fINote\fR \ \(em\ The reference for all parameters associated with the
transmission path interface shall be the relevant output interface as defined 
in Recommendation\ G.703. 
.RT
.sp 1P
.LP
4.1
	\fIImpedance\fR 
.sp 9p
.RT
.PP
The transmission path interface shall have the nominal impedance as defined 
in Recommendation\ G.703 for the relevant bit rate output 
interface.
.RT
.sp 1P
.LP
4.2
	\fIReturn loss\fR 
.sp 9p
.RT
.PP
With the transmission path interface terminated with its nominal
impedance, the return loss shall comply with the requirements defined in
Recommendation\ G.703 for the relevant bit rate output interface. This shall
apply with any value of load impedance, including short and open circuits,
applied to the protected monitoring point.
.RT
.sp 1P
.LP
4.3
	\fIAttenuation\fR 
.sp 9p
.RT
.PP
The attenuation in the transmission path, when the transmission
path interface is terminated in its nominal impedance, shall be less than
\fIY\fR \ dB (see Figure\ 2/G.772) for all frequencies in the range 2.5% 
to 150% of 
the nominal bit rate, when the protected monitoring point is terminated 
in any load impedance, including short and open circuit. 
.PP
The value of \fIY\fR is for further study; 1\ dB has already been
proposed.
.RT
.sp 1P
.LP
4.4
	\fIImpact of the protected monitoring point on the maximum cable\fR 
\fIlength\fR 
.sp 9p
.RT
.PP
The introduction of a protected monitoring point as described in
Figure\ 1b with an attenuation of \fIY\fR \ dB will effectively reduce 
the maximum 
attenuation allowed for in Recommendation\ G.703 by \fIY\fR \ dB.
.RT
.sp 1P
.LP
4.5
	\fIProtection of the transmitted signal\fR 
.sp 9p
.RT
.PP
Under study.
.PP
The degree of protection shall be specified in terms of an X%
variation in the pulse mask of the signal on the transmission path when the
protected monitoring point is terminated in any impedance including short 
and open circuit. 
.RT
.LP
.rs
.sp 9P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 29P
.ad r
\fBFigure 1/G.772, p. 10\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 11P
.ad r
\fBFigure 2/G.772, p. 11\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
	\fBReferences\fR 
.sp 1P
.RT
.LP
[1]
	CCITT Recommendation \fIMaintenance terminology and definitions,\fR 
Vol.\ IV, Rec.\ M.60.
.LP
[2]
	CCITT Recommendation \fIPhysical/electrical characteristics of\fR 
\fIhierarchical digital interfaces\fR , Vol.\ III, Rec.\ G.703.
.LP
[3]
	CCITT Recommendation \fIResistability of subscribers terminals to\fR 
\fIovervoltages and overcurrents\fR , Vol.\ IX, Rec.\ K.21.
.LP
[4]
	IEC Publication 801\(hy2 \fIPrescriptions relatives aux d\*'echarges\fR 
\fI\*'electrostatiques\fR .
.LP
.bp