1、INTERNATIONAL TELECOMMUNICATION UNION lTU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU SERIES U: TELEGRAPH SWITCHING Intex service u.102 (07/96) Intex and similar services - Network requirements to effect interworking between terminals operating at different speeds ITU-T Recommendation U.102 (P
2、reviously “CCIlT Recommendation”) ITU-T U-SERIES RECOMMENDATIONS TELEGRAPH SWITCHING General Specific signalling schemes and interworking between signalling systems Signalling over radio and multiplexed channels Gentex signalling Particular signalling facilities Radiotelex interworking Interworking
3、between new information services and telex Telex store and forward Definitions The international telex service u. l-u. 10 U.11-U.19 U.20-U.29 U.30-U.39 U.40-US9 U.60-U.69 U.70-U.79 U.80-U.99 U.140-U. 199 U.200-U.299 For further details, please refm to ITLJ-T List of Recommendations. STD-ITU-T RECMN
4、U.LO2-ENGL L77b 48b2591 Ob222b4 70T = FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (IT). The IT-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view
5、 to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the IT-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendat
6、ions by the Members of the IT-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITLJ-T Recommendation U.102 was prepared by ITU-T Study Group 1 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 19th of July 1996. NOTE In this R
7、ecommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1996 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanica
8、l, including photocopying and microfilm, without permission in writing from the IT. Recommendation U.102 (07196) i CONTENTS Page 1 Introduction 1 3 Call routing and establishment 1 4 Character transfer 2 5 Flow control of characters 2 1 2 References . . ii Recommendation U.102 (07196) SUMMARY This R
9、ecommendation describes the network requirements to be met in order to allow successful interworking of INTEX terminals operating at different information transfer rates. Recommendation U.102 (07/96) iii STD-ITU-T RECMN U-LUZ-ENGL 177b 4862591 Ob222b8 555 9 Recommendation U.102 INTEX1) AND SIMILAR S
10、ERVICES - NETWORK REQUIREMENTS TO EFFECT INTERWORKING BETWEEN TERMINALS OPERATING AT DIFFERENT SPEEDS (Geneva, 1996) 1 Introduction This Recommendation describes the network requirements to be met in order to allow successful interworking of INTEX terminals operating at different speeds. 2 Reference
11、s The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: all users of t
12、his Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid IT-T Recommendations is regularly published. CCITT Recommendation F. 150 (1991), Service and operatio
13、nal provision for intex service. CCKT Recommendation F.82 (1991), Operational Provisions to permit interworking between the international telex service and the intex service. -T Recommendation 5.33 (1993), Alphabets andpresentation characteristics for the intex services. -T Recommendation S.34 (1993
14、), Intex terminals - Requirements to effect interworking with the international telex service. IT-T Recommendation S.35 (1993), Answerback codingfor the intex. -T Recommendation S.36 (1996), Intex and similar services - Terminal requirements to effect intenvorking between terminals operating at diff
15、erent speeds. IT-T Recommendation U.210 (1993), Intex service network requirements to effect interworking with the international telex service. - - - - - - - 3 Call routing and establishment 3.1 Calls originating from INTEX (or similar service) terminals shall normally be routed over circuits operat
16、ing at a speed not less than that of the calling terminal until received at the switching centre from which the called terminal is served. This terminating switching centre will know the speed at which the called terminal operates. An originating or transit switching centre may route calls from INTE
17、X (or similar service) terminals over trunk circuits operating at a speed lower than that of the calling terminal (but not lower than that of the called terminal) if that switching centre is able to determine the speed of the called destination from, for example, examination of the addressing inform
18、ation received. 3.2 On calls incoming from a type E trunk, which are routed to a circuit (customer line or trunk) which operates at a slower speed than the calling circuit, the switching centre making the connection to the slower circuit shall transmit a call progress signal 92,93 or 94 to the calli
19、ng type E circuit during call establishment as detailed in clause 1/U.101. The call progress signal to be transmitted shall depend upon the speed of the called circuit. Provisional name (see Recommendation F. 150). Recommendation U.102 (07196) 1 - 3.3 On calls incoming from a type F trunk, which are
20、 routed to a circuit (customer line or trunk) which operates at a slower speed than the called circuit, the switching centre making the connection to the slower circuit shall transmit a call connected signal to the calling type F circuit which indicates the speed of the called circuit as detailed in
21、 clause 2. 101. 3.4 On calls incoming from INTEX (or similar service) customer lines an originating switching centre shall transmit a Speed Indicator sequence (as detailed in clauses 1 and 2/iJ.101 indicating the speed of the slower terminal involved in the call. The Speed Indicator sequence to be t
22、ransmitted shall be determined from the speeds of the calling and called circuits, in conjunction with any call progress signal 92, 93 or 94 (type E outgoing circuits) or call connected signai (type F outgoing circuits) received from a subsequent switching centre during call establishment. 4 Charact
23、er transfer On calls between INTEX (or similar service) terminals the network shall transfer any characters between the calling and called circuits (and vice versa) as received. No checking of parity shall be undertaken by the network. 5 Flow control of characters 5.1 trunk) operating at different s
24、peeds shall be known as the conversion centre. A switching centre which effects connection between two INTEX (or similar service) circuits (customer line or 5.2 The conversion centre shall provide character flow control facilities for the duration of the call. 5.3 The faster of the higher speed term
25、inals is required to lower the rate at which it transmits characters to that of the slower terminal. However, to allow for delays and small character rate differences the conversion centre shall also provide a buffer store for characters requiring transmission to the slower speed circuit and shall o
26、perate flow control procedures with the faster of the higher speed terminals. 5.4 When the buffer contains more than a specific number of characters (Threshold 1) awaiting transmission to the outgoing circuit, the conversion centre shall transmit an X-OFF character (IA5 character 1/3) to the incomin
27、g circuit. If the buffer continues to fill, additional X-OFF characters shall be transmitted to the incoming circuit. The conversion centre shall not rely upon a single generation of the X-OFF character (at Threshold 1) to achieve flow control because of the possibility of corruption of this charact
28、er before reception by the faster terminal. 5.5 The conversion centre shall continue to transmit the contents of the buffer to the outgoing circuit. 5.6 shall immediately clear both circuits. If the number of characters in the buffer reaches the maximum permitted (Threshold 2) the conversion centre
29、5.7 After transmission of one or more X-OFF characters, the conversion centre shall transmit the X-ON character (IA5 111) to the faster circuit when the number of characters in the buffer awaiting transmission to the outgoing circuit has fallen below a specific number (Threshold 3). 5.8 If after tra
30、nsmission of the X-ON character, no further characters are received from the incoming circuit, the conversion centre shall transmit further X-ON characters at frequent intervals until a character is received from the incoming circuit, or until a clearing signal is received from either circuit. The c
31、onversion centre shall not rely upon a single operation of the X-ON character (at Threshold 3) to achieve flow control because of the possibility of corruption of this character before reception by the originating terminal. 5.9 The choice of values for Thresholds 1, 2 and 3 is a matter for individua
32、l ROAS to determine by bilateral agreement. However, in order that the delay from transmission of an ENQ signal from an INTEX (OT similar service) terminal and reception of the consequent answerback is kept within acceptable limits, Threshold 2 shall not exceed 50 characters. Furthermore, to allow f
33、or propagation and switching delays, plus the response time of the INTEX (or similar service) terminal to a received X-OFF character, the interval between Thresholds 1 and 2 shall not be less than 25 characters. 2 Recommendation U.102 (07/96) eries A eries B eries C eries D eries E eries F ieries G
34、leries H keries I ienes J ieries K Series L Series M Series N Series O Series P Series Q Series R Series S Series T Series U Series V Series X Series Z ITU-T RECOMMENDATIONS SERIES Organization of the work of the ITU-T Means of expression General telecommunication statistics General tariff principle
35、s Telephone network and ISDN Non-telephone telecommunication services Transmission systems and media Transmission of non-telephone signals Integrated services digital network Transmission of sound-programme and television signals Protection against interference Construction, installation and protect
36、ion of cables and other elements of outside plant Maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leasr circuits Maintenance: international sound-programme and television transmission circuits Specifications of measuring equipment Telephone transmission
37、 quality Switching and signalling Telegraph transmission Telegraph services terminai equipment Terminal equipments and protocols for telematic services Telegraph switching Data communication over the telephone network Data networks and open system communication Programming languages Printed in Switzerland Geneva, 1996
