ITU-T X 352-1988 INTERWORKING BETWEEN PACKET SWITCHED PUBLIC DATA NETWORKS AND PUBLIC MARITIME MOBILE SATELLITE DATA TRANSMISSION SYSTEMS《分组交换公用数据网(PSPDNs)与公用海事卫星移动数据传输系统之间的互通》.pdf
《ITU-T X 352-1988 INTERWORKING BETWEEN PACKET SWITCHED PUBLIC DATA NETWORKS AND PUBLIC MARITIME MOBILE SATELLITE DATA TRANSMISSION SYSTEMS《分组交换公用数据网(PSPDNs)与公用海事卫星移动数据传输系统之间的互通》.pdf》由会员分享,可在线阅读,更多相关《ITU-T X 352-1988 INTERWORKING BETWEEN PACKET SWITCHED PUBLIC DATA NETWORKS AND PUBLIC MARITIME MOBILE SATELLITE DATA TRANSMISSION SYSTEMS《分组交换公用数据网(PSPDNs)与公用海事卫星移动数据传输系统之间的互通》.pdf(12页珍藏版)》请在麦多课文档分享上搜索。
1、INTERNATIONAL TELECOMMUNICATION UNION)45 4 8 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%27/2+). “%47%. .%47/2+3-/“),% $!4! 42!.3-)33)/. 3934%-3).4%27/2+). “%47%. 0!#+%437)4#(%$ 05“,)# $!4! .%47/2+3 !.$05“,)# -!2)4)-% -/“),% 3!4%,)4% $!4!42!.3-)33)/. 3934%-3)45 4 Recommendation 8 (Extract from
2、the “LUE “OOK)NOTES1 ITU-T Recommendation X.352 was published in Fascicle VIII.6 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are identical to the Blue Book v
3、ersion and copyright conditions remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may be r
4、eproduced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle VIII.6 - Rec. X.352 1Recommendation X.352INTERWORKING BETWEEN PACKET SWITCHED PUBLIC DATA NETWORKSAND PUBLIC MARITIME MOBILE SATELLITE
5、DATA TRANSMISSION SYSTEMS(Malaga-Torremolinos, 1984; amended at Melbourne, 1988)The CCITT,considering(a) that the Maritime Satellite is now being operated by the International Maritime Satellite Organization(INMARSAT);(b) that interworking between the Maritime Satellite Service and public data netwo
6、rks is required;(c) that Recommendation X.350 specifies general interworking requirements for data transmission in PublicMobile Satellite Systems and Recommendation X.353 outlines the routing principles for interconnecting Public MobileSatellite Systems with public data networks;(d) that Recommendat
7、ion X.25 specifies the interface between data terminals and data circuit-terminatingequipment for terminals operating in the packet mode on public data networks, and that Recommendation X.75 specifiesdetailed procedures applicable to call control between public networks providing data transmission s
8、ervices;(e) that the physical link between a mobile earth station and a data switching exchange (DSE) will only existon a temporary basis, i.e. so long as a virtual call exists between the ship and the DSE;(f) that Recommendation X.141 provides guidance with respect to general principles for the det
9、ection andcorrection of errors in public data networks,unanimously recommendsthat the following interworking principles and interface conditions should apply for operations at the networklayer in the packet mode between a mobile DTE and a public data network.1 DefinitionsFor definitions of terms use
10、d in relation with data transmission in public mobile satellite systems, seeRecommendation X.350.For the purpose of this Recommendation the mobile satellite data switching exchange (MSDSE) is defined asthe functional interface between the public mobile satellite data transmission system and a packet
11、 switched public datanetwork.The MSDSE provides the following functions:- interworking between the signalling systems used in the public mobile satellite data transmission systemand the PSPDN;- routing and call control for calls to and from mobile earth stations;- charging.The composition of the pub
12、lic maritime mobile satellite data transmission system for interconnection withpacket switched PDN is shown in Figure 1/X.352.The Packet Switched Data Access Unit (PSDAU) provides a means of interconnecting a mobile DTE with theterrestrial packet switched public data network, through a mobile earth
13、station and coast earth station equipped withpacket switched data facility.2 Fascicle VIII.6 - Rec. X.352Fascicle VIII.6 - Rec. X.352 32 Interface conditionsThe following interfaces need to be specified for interworking and call control purposes:- the interface between the mobile DTE and the PSDAU (
14、mobile local circuit);- the interface between the PSDAU and the mobile earth station (mobile local circuit);- the interface between the mobile earth station and the coast earth station including the interface to thenetwork coordination station (mobile satellite circuit);- the interface between the c
15、oast earth station and the MSDSE (mobile terrestrial circuit);- the interface between the MSDSE and a packet switched PDN.The interfaces are shown for layers 1, 2 and 3 in Figure 2/X.352.2.1 Interface between the mobile DTE and the Packet Switched Data Access Unit (PSDAU)2.1.1 Layer 1 (physical laye
16、r) between the mobile DTE and the PSDAU may be realised by the use of the interfacesdefined in:- Recommendation X.21;- Recommendation X.21 bis;- Recommendation V.24 and V.25.The Recommendation X.21 interface should be included in new PSDAU designs. The Recommendation X.21bis interface (or the Recomm
17、endation V.24 interface) may be used for existing designs.The basic requirements of the layer 1 interface are:i) For calls originating in the mobile DTE the interface should provide for the following functions:- it should enable the DTE to provide the mobile earth station with the address of the coa
18、st earth stationthrough which the call is to be established, and the access-request code of the packet switched dataservice.Note 1 - The address of the call DTE is provided as part of the level 3 procedure.Note 2 - The PSDAU should provide an indication of call progressa) visually, for use by an ope
19、rator; and/orb) as call progress signals to the DTE when the attempt to establish the mobile satellite circuit fails. Thecall progress signals to be used are given in 6.1. Such call progress signals to the DTE may not bepossible always, e.g. when the DTE interfaces the PSDAU in accordance with Recom
20、mendationV.24.ii) For calls originating in a PDN the interface should allow for automatic connection of the mobile DTE tothe circuit.Interchange circuits shall be provided in order to meet these requirements. The required interchange circuits aredefined in the Recommendations applicable to the inter
21、face used. The control of these interchange circuits shall be suchas to ensure proper establishment and clearing of the mobile satellite circuit. It should also be observed that since mobilesatellite circuit is established on a call by call basis, it must be ensured that the mobile DTE acquires sync
22、hronism to theelement timing of the PDN before the full procedure on layer 2 is established. Until synchronism is obtained the DTEshould send contiguous 1s.See also Recommendation X.32.2.1.2 Layer 2 should be in accordance with 2 of Recommendation X.25. The extended control field (module 128)may be
23、used if required.Note - For reasons given in Recommendation X.141 it may be advantageous to use the selective reject (SREJ)command.The mobile DTE should start sending the flag sequence as soon as synchronism with the MSDSE has beenestablished.4 Fascicle VIII.6 - Rec. X.3522.1.3 Layer 3 should be in
24、accordance with 3 through 7 of Recommendation X.25.Default values for network layer parameters such as number of virtual connections, use of extended packetsequence numbering, window size, packet size and throughput may be defined by the service provider.Composition of the address field of the call
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