1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 ) TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%2!4%$G0G03%26)#%3$)4!,G0G0.%47/2+G0G0 )3$.G9/6%2!,G0G0.%47/2+G0G0!30%#43!.$G0G0 amended at Melbourne, 1988)1 GeneralThe ISDN may be described by a limited set of user-network interfaces (refer to Recommen
2、dation I.411) and alimited set of ISDN connection types to support the telecommunication services described in the I.200-Series ofRecommendations. This Recommendation identifies and defines these connection types which are a description of thelower layer functions (refer to Recommendation I.310) of
3、the ISDN network needed to support the basic services.This Recommendation should be considered in conjunction with other Recommendations in the I-Series, withparticular reference to Recommendations I.120, I.200-Series, I.310, I.320, I.324, I.411 and I.412. For definitions ofterms used in this Recomm
4、endation, refer to Recommendation I.112.2 Basic concept of ISDN connection types2.1 IntroductionAn ISDN provides a set of network capabilities which enable telecommunication services to be offered to auser (refer to I.200-Series Recommendations).ISDN connection types are a description, using the att
5、ribute method of Recommendation I.140, of the basiclow layer functions (BLLFs) of the ISDN. The set of possible values of attributes is given in 3. It is possible to selectcombinations of attribute values which are either impractical or of little use; therefore, a set of agreed connection types isgi
6、ven in 3.An ISDN connection is a connection established between ISDN reference points (see Recommen-dations I.310, I.410 and I.411). All ISDN connections are made to support a request for an ISDN service and are timedependent and of finite duration. All ISDN connections will fall under the category
7、of one or other of the connectiontypes. It follows therefore that an ISDN connection type is a time dependent description and an ISDN connection is aninstance of a type.2.2 Purpose of international connection typesThe definition of a set of ISDN connection types provides the necessary input to ident
8、ify the networkcapabilities of ISDNs. Other key requirements of an ISDN are contained in other I-Series Recommendations, inparticular in Recommendations I.310, I.410 and I.411.In addition to describing network capabilities of an ISDN, the identification of ISDN connection typesfacilitates the specif
9、ication of network-to-network interfaces. It will also assist in the allocation of network performanceparameters.It should be noted that the user specifies only the service required while the network allocates resources to setup a connection of the specific type as necessary to support the requested
10、 service. It is further noted that for certainservices additional functions (e.g. additional lower layer functions and or higher layer functions) may be required asdepicted in Figure 1/I.340. For examples of such cases, refer to Recommendation I.310.2.3 Functions associated with ISDN connection type
11、sAny ISDN connection type involves an association of functions to support telecommunication services. Thesefunctions are fully described in Recommendation I.310.2 Fascicle III.8 Rec. I.340d01FIGURE 1/I.340.D012.4 Applications of ISDN connection typesFour situations have been identified thus far to w
12、hich ISDN connection types apply: between two ISDN user-network interfaces, i.e. between S/T reference points (refer to Figure 2a/I.340);(Note There may be a need in certain cases to differentiate between the S and T reference points. This isfor further study.) between an ISDN user-network interface
13、 and an interface to a specialized network resource (refer toFigure 2b/I.340); between an ISDN user-network interface and a network-to-network interface (refer to Figure 2c/I.340); between two ISDN-to-other network interfaces (refer to Figure 2d/I.340).2.5 ISDN connection involving several networksA
14、n ISDN connection may comprise a number of tandem network connections. Figure 3/I.340 shows anexample in which each end network is an ISDN. The intermediate networks may or may not be ISDNs but they offer theappropriate network capabilities for the service supported by the (overall) ISDN connection.
15、 Other configurations are forfurther study.In (overall) ISDN connections involving several networks, each network provides a part of the connection andmay be categorized by different attribute values. In such cases, the characterization of the performance for the overallISDN connection is for furthe
16、r study.3 ISDN connection types and their attributes3.1 Attributes and their valuesISDN connection types are characterized by a set of attributes. Each attribute has a set of admissible values.The definitions of these attributes are given in Recommendation I.140. Table 1/I.340 of this Recommendation
17、 lists theset of attributes and their possible values for connection types and connection elements. The concept of connectionelements is explained in detail in 4.Figure 4/I.340 shows an example of three different ISDN connections distinguished by differing values for theattribute “topology” in their
18、 ISDN connection types. Values for the other attributes of the connection type may be thesame, e.g. speech.Fascicle III.8 Rec. I.340 333d02FIGURE 2/I.340.D02The attributes which are associated with the ISDN connection types have a similarity to those used to definetelecommunication services in Recom
19、mendations I.211 and I.212. However, the two sets of attributes differ in severalimportant aspects. For example:a) ISDN connection types represent the technical capabilities of the network and are a means to ensuredefined performance and interworking between networks. Telecommunication services supp
20、orted by theISDN are the packages offered to users and the definition of their attributes is the means to standardizethe service offerings worldwide.b) Quality of service and commercial attributes are relevant to telecommunication services, whereas networkperformance, network operation and maintenan
21、ce attributes are relevant to connection types.4 Fascicle III.8 Rec. I.340d03FIGURE 3/I.340.D03d04FIGURE 4/I.340.D043.2 Rules of association for the attribute values of connection elements and connection typesThis section describes the relationship between the attribute values of connection elements
22、 and connectiontypes (see Table 1/I.340). For each attribute the possible values recommended are listed. The definitions of the attributesand attribute values are contained in Recommendation I.140. In addition to the (possible) attribute values applicable tothe connection elements, an association la
23、w is given (where appropriate) for each attribute to show how the value of theattribute for the overall connection type is obtained from the values of the attribute applicable to the connectionelements.Fascicle III.8 Rec. I.340 5TABLE 1/I.340Values already identified for attributes for ISDN connecti
24、onelements and connection typesValues for attributesAttributesAccess connection elementNational or international transitconnection elementOverall connection type1 Information transfermodeCircuit, packet Circuit, packet Circuit, packet2 Information transferrateLayer 1Layer 2Layer 364, 2 64, 384, 1536
25、, 1920Throughput options for FSThroughput options for FS(16, 32), 64, 2 64, 384, 1536,1920Throughput options for FSThroughput options for FS(16, 32), 64, 2 64, 384, 1536,1920Throughput options for FSThroughput options for FS3 Information transfersusceptanceSpeech processing equipmente.g. LRE, speech
26、 interpolation,/A conversion, echosuppression equipment, nullSpeech processing equipmente.g. LRE, speech interpolation,/A conversion, echosuppression equipment,multisatellite hops, nullUnrestricted digital, 3.1 kHzaudio, speech4 Establishment ofconnectionSwitched, semi-permanent,permanentSwitched, s
27、emi-permanent,permanentSwitched, semi-permanent,permanent5 Symmetry Unidirectional, bidirectional,symmetric, bidirectionalasymmetricUnidirectional, bidirectional,symmetric, bidirectionalasymmetricUnidirectional, bidirectional,symmetric, bidirectionalasymmetric6 ConnectionconfigurationTopologyUniform
28、ityDynamicsPoint-to-point (simple, tandemor 2 64 parallel)Uniform, non uniformNot applicablePoint-to-point (simple, tandemor 2 64 parallel) multipointUniform, non uniformNot applicableLocal, national, international(simple or 2 64 parallel)Not applicableConcurrent, sequential,add/remove, symmetry and
29、/ortopology change7 StructureLayer 1Layer 2Layer 38 kHz integrity, 8 kHz integritywith RDTD, unstructuredSDU integrity, unstructuredSDU integrity, unstructured8 kHz integrity, 8 kHz integritywith RDTD, unstructuredSDU integrity, unstructuredSDU integrity, unstructured8 kHz integrity, 8 kHz integrity
30、with RDTD, unstructuredSDU integrity, unstructuredSDU integrity, unstructured8 Channel (rate)Information channelSignalling channelD(16), D(64), B(64), H0(384),H11(1536), H12(1920)D(16), D(64), D(16) + B(64),D(64) + B(64)64, 1536, 1920, analogueCommon channel signallingsystem, packetNot applicable6 F
31、ascicle III.8 Rec. I.340TABLE 1/I.340 (cont.)Values for attributesAttributesAccess connection elementNational or international transitconnection elementOverall connection type9 Connection controlprotocola)Layer 2Layer 3Rec. I.441, Rec. X.25 linklevelc) d), or nullRec. I.451, Rec. X.25 packetlevelc)
32、d)Rec. Q.703, Rec. X.75 linklevelc), Rec. X.25 link levelc)Rec. Q.704 + SCCP,Rec. X.75 packet level,Rec. Q.704 + ISUP, Rec. X.25packet level c), nullNot applicableLayer 1, Rec. I.430, Rec. I.431,Rec. Q.702, Rec. X.75 physicallevelc), Rec. X.25 physicallevelc)10 Information transfercoding protocol a)
33、Layer 1Layer 2Layer 3Rec. I.430, Rec. I.431,Rec. G.711Rec. I.441, Rec. X.25 linklevel c), or nullRec. I.451, Rec. X.25 packetlevel c) d)or nullRec. G.711, Rec. Q.702,Rec. X.75 physical level c),Rec. X.25 physical level c)Rec. Q.703, Rec. X.75 linklevel c), Rec. X.25 link level c)or nullRec. Q.704 +
34、SCCP,Rec. X.75 packet level c),Rec. Q.704 + ISUP, Rec. X.25packet level c)or nullNot applicable11 Networkperformance b)a) Errorperformanceb) Slip performanceRec. G.821Rec. G.822Rec. G.821Rec. G.822Rec. G.821Rec. G.82212 NetworkinterworkingFS FS FS13 Operations andmanagementFS FS FSFS further studya)
35、Where there are two or more S/T interfaces, different values of access attributes (attributes 8, 9 and 10) may occur at eachinterface. Values need to be specified for each channel of the interface structure. The role of the access attributes indetermining connection types is for further study. Inter
36、faces to network specialized resources and to other networks are forfurther study.b)Examples of the additional performance attributes which may be defined are: call and packet processing delays; probability of call failure due to congestion; probability of call failure due to network malfunction or
37、packet mishandling; information transfer delay; error performance including attributes 11 a) and 11 b).c)Use of Rec. X.25 and X.75 in ISDN can be found in Rec. X.31.d)Packet connection establishment/release may be a two stage process: stage 1 the selection of a B-channel, stage 2 the setting upof a
38、packet connection. For further details, see Rec. X.31.Fascicle III.8 Rec. I.340 73.2.1 Information transfer modeAttribute values for connection elementsCircuit or packet.Attribute values for overall connection typeCircuit or packet.Association lawDue to the nature of current packet systems, the use
39、of packet mode in any connection element would make theoverall connection type a packet type.3.2.2 Information transfer rate (kbit/s)Attribute values for connection elements16 or 32 or 64 or 2 64 or 384 or 1536 or 1920(Values 16 and 32 are not allowed in the access connection element).Attribute valu
40、es for overall connection type(16 or 32) or 64 or 2 64 or 384 or 1536 or 1920.Association lawThe value for the overall connection type will be equal to the lowest value of any of its connection elements.3.2.3 Information transfer susceptanceAttribute values for connection elementsSpeech processing f
41、unctions (e.g. low rate encoding (LRE) equipment, speech interpolation, /A lawconversion) and/or echo suppression functions and/or multiple satellite hops or null.The exact means of specification of the attribute is for further study. One method would be an appropriatereference to a Recommendation d
42、etailing operational requirements in the ISDN.Attribute values for overall connection typesUnrestricted digital information or 3.1 kHz audio or speech.Association lawFor an overall connection type to have the value unrestricted digital, no connection element may containspeech processing functions or
43、 echo suppression functions. Connection elements containing speech processingdevices having the flexibility to change operation between speech and 64 kbit/s unrestricted would on the otherhand be allowed to be a part of a number of different connection types.For an overall connection type to have th
44、e value 3.1 kHz audio, it may contain echo suppression functions (orit has to disable them prior to data transfer); it must however contain /law conversion equipment whenappropriate.For an overall connection type to have the value speech, it must contain /law conversion equipment and echosuppression
45、 functions when appropriate.These matters are dealt with in more detail in Recommendation I.335.3.2.4 Establishment of connectionAttribute values for connection elementsSwitched or semi-permanent or permanent.Attribute values for overall connection typeSwitched or semi-permanent or permanent.8 Fasci
46、cle III.8 Rec. I.340Association lawIf all connection elements are permanent, then the overall connection type is permanent.If any of the connection elements are switched, then the overall connection type is switched. If one or more ofthe connection elements are semi-permanent and none of the connect
47、ion elements are switched, then theoverall connection type is semi-permanent.3.2.5 SymmetryAttribute values for connection elementsUnidirectional or bidirectional symmetric or bidirectional asymmetric.Attribute values for the overall connection typeUnidirectional or bidirectional symmetric or bidire
48、ctional asymmetric.Association lawThe overall symmetry can only be generated from the connection elements by analysis of the connectionelement values in the context of the architecture of the connection.3.2.6 Connection of configuration3.2.6.1 TopologyAttribute values for connection elementsPoint-to
49、-point (simple, tandem or 2 64 parallel), or multipoint.(The access connection element may not be multipoint.)Attribute values for the overall connection typeLocal or national or international. (Each simple or 2 64 parallel.)Association lawNo association is possible.3.2.6.2 UniformityAttribute values for connection elementsUniform or non-uniform.Attribute values for the overall connection typeNot applicable.Association lawNot applicable.3.2.6.3 DynamicsAttribute values for connection elementsNot applicable.Attribute values
