1、 ETSI TS 102 636-5-1 V1.1.1 (2011-02)Technical Specification Intelligent Transport Systems (ITS); Vehicular Communications;GeoNetworking;Part 5: Transport Protocols; Sub-part 1: Basic Transport ProtocolETSI ETSI TS 102 636-5-1 V1.1.1 (2011-02) 2Reference DTS/ITS-0030006 Keywords addressing, ITS, net
2、work, point-to-multipoint, point-to-point, protocol ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important no
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6、be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2011. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTM, TIPHONTM, the TIPHON logo and the ETSI logo are Trade Mar
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8、nd the GSM logo are Trade Marks registered and owned by the GSM Association. ETSI ETSI TS 102 636-5-1 V1.1.1 (2011-02) 3Contents Intellectual Property Rights 4g3Foreword . 4g3Introduction 4g31 Scope 5g32 References 5g32.1 Normative references . 5g32.2 Informative references 5g33 Definitions and abbr
9、eviations . 6g33.1 Definitions 6g33.2 Abbreviations . 6g34 Services provided by the Basic Transport Protocol . 6g35 Format convention 7g36 BTP packet structure 8g37 BTP header . 8g37.1 Overview 8g37.2 BTP-A header . 9g37.2.1 Structure of the BTP-A header . 9g37.2.2 Fields of the BTP-A header 9g37.3
10、BTP-B header . 9g37.3.1 Structure of the BTP-B header 9g37.3.2 Fields of the BTP-B header 9g38 Protocol operations . 10g38.1 General . 10g38.2 Source operations . 10g38.3 Destination operations 11g3Annex A (informative): BTP data services . 12g3A.1 General . 12g3A.2 BTP-Data.request . 12g3A.3 BTP-Da
11、ta.indication . 13g3Annex B (informative): Bibliography . 14g3History 15g3ETSI ETSI TS 102 636-5-1 V1.1.1 (2011-02) 4Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any
12、, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on
13、 the ETSI Web server (http:/webapp.etsi.org/IPR/home.asp). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) wh
14、ich are, or may be, or may become, essential to the present document. Foreword This Technical Specification (TS) has been produced by ETSI Technical Committee Intelligent Transport System (ITS). The present document is part 5, sub-part 1 of a multi-part deliverable covering Networking and Transport,
15、 as identified below: Part 1: “Requirements“; Part 2: “Scenarios“; Part 3: “Network architecture“; Part 4: “Geographical addressing and forwarding for point-to-point and point-to-multipoint communications“; Part 5: “Transport Protocols“: Sub-part 1: “Basic Transport Protocol“; Part 6: “Internet Inte
16、gration“. Introduction The Basic Transport Protocol (BTP) provides an end-to-end, connection-less transport service in the ITS ad hoc network. Its main purpose is the multiplexing of messages from different processes at the ITS Facilities layer, e.g. CAM and DEN services, for the transmission of pac
17、kets via the GeoNetworking protocol as well as the de-multiplexing at the destination). BTP enables the protocol entities at the ITS Facilities layer to access services of the GeoNetworking protocol and to pass protocol control information between the ITS Facilities layer and the GeoNetworking proto
18、col. Message multiplexing/demultiplexing is based on ports, an ITS station-internal, 16 bit address. A port represents a communication endpoint that identifies the ITS station protocol entity at the source (source port) and the destination (destination port). The usage of ports is similar to the two
19、-stage packet transport in the IP protocol suite, where the IP provides the routing of packets from source to destination and UDP the multiplexing/demultiplexing of messages from/to application processes. In the case of BTP, the GeoNetworking protocol transports the packets among the ITS stations an
20、d the BTP protocol delivers the packet to the entities at the ITS Facilities layer. BTP also adopts the concept of “well-known ports“ from the IP protocol suites that assigns fixed ports to specific ITS Facilities layer protocols. The definition of the ports, however, is beyond the scope of the pres
21、ent standard. BTP is a lightweight protocol: It has a 4-byte protocol header and requires minimal processing. It provides an unreliable transport of packets, i.e. packets can arrive out-of-order, appear duplicated or can be lost. The design of BTP assumes that entities using the protocol are either
22、tolerant against the unreliable packet transport or provide appropriate mechanisms for reliable communication in their protocols. ETSI ETSI TS 102 636-5-1 V1.1.1 (2011-02) 51 Scope The present document specifies the ITS Basic Transport Protocol (BTP) for the transport of packets among ITS stations i
23、n the ITS ad hoc network. It provides an end-to-end, connection-less and unreliable transport service. 2 References References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For
24、 non-specific references, the latest version of the reference document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http:/docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause
25、were valid at the time of publication ETSI cannot guarantee their long term validity. 2.1 Normative references The following referenced documents are necessary for the application of the present document. 1 ETSI EN 302 665: “Intelligent Transport Systems (ITS); Communications Architecture“. 2 ETSI T
26、S 102 636-1: “Intelligent Transport Systems (ITS); Vehicular Communications; GeoNetworking; Part 1: Requirements“. 3 ETSI TS 102 636-2: “Intelligent Transport Systems (ITS); Vehicular Communications; GeoNetworking; Part 2: Scenarios“. 4 ETSI TS 102 636-3: “Intelligent Transport Systems (ITS); Vehicu
27、lar Communications; GeoNetworking; Part 3: Network architecture“. 2.2 Informative references The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. i.1 ETSI ES 202 663: “Intelligent Transport
28、 Systems (ITS); European profile standard for the physical and medium access control layer of Intelligent Transport Systems operating in the 5 GHz frequency band“. i.2 ETSI TS 102 636-4-1: “Intelligent Transport System (ITS); Vehicular communications; GeoNetworking; Part 4: Geographical addressing a
29、nd forwarding for point-to-point and point-to-multipoint communications; Sub-part 1: Media independent functionalities“. i.3 ETSI TS 102 636-4-2: “Intelligent Transport Systems (ITS); Vehicular Communications; GeoNetworking; Part 4: Geographical addressing and forwarding for point-to-point and point
30、-to-multipoint communications; Sub-part 2: Media dependent functionalities for ITS-G5A media“. i.4 ETSI TS 102 637-2: “Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set of Applications; Part 2: Specification of Cooperative Awareness Basic Service“. i.5 IETF RFC 768: “User Data
31、gram Protocol“. ETSI ETSI TS 102 636-5-1 V1.1.1 (2011-02) 63 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the terms and definitions given in 1, 4 and the following apply: destination: receiving BTP entity in the ITS station destination port: port at which t
32、he destination is expected to listen for a BTP packet port: ITS station-internal address that identifies a protocol entity at the ITS facilities layer source: originating BTP entity in the ITS station source port: port at which the source of the BTP packet is listening for a reply BTP packet 3.2 Abb
33、reviations For the purposes of the present document, the abbreviations given in 1, 4 and the following apply: BTP Basic Transport Protocol FL Facilities Layer4 Services provided by the Basic Transport Protocol The Basic Transport Protocol (BTP) provides an end-to-end, connection-less transport servi
34、ce in the ITS ad hoc network 4. Similar to UDP i.5, it offers a minimal transport service, i.e. the non-guaranteed delivery of BTP-PDUs among BTP entities. It also allows protocol entities at the ITS facilities layer to directly access the services provided by the GeoNetworking protocol. The BTP sha
35、ll meet the requirements specified in 2 and support the use cases defined in 3. The BTP provides services to ITS Facilities Layer protocol entities (figure 1), such as CAM i.4 and DENM 4. The services are provided via the BTP-SAP using service primitives of different types that carry parameters and
36、the PDU of the upper protocol entity, i.e. FL-PDU. In order to provide its packet transport services, BTP uses the services of the GeoNetworking protocol i.3. ETSI ETSI TS 102 636-5-1 V1.1.1 (2011-02) 7Figure 1: SAPs, SDUs and PDUs relevant for the BTP The present document specifies the following SA
37、Ps: BTP-SAP between BTP and the ITS Facilities layer; and BTP-Mgmt-SAP between the BTP and the ITS Network and Transport Management. 5 Format convention The basic convention for the present specification is illustrated in figure 2. The bits are grouped into bytes. The bits of an octet are always sho
38、wn horizontally and are numbered from 0 to 7. Up to 4 octets are shown horizontally; multiple sets of 4 octets are grouped vertically. Octets are numbered from 0 to N-1. The octets are transmitted in ascending numerical order; inside an octet the bit 0 is transmitted first. When a field is contained
39、 within a single octet, the highest bit number of the field represents the lowest order value. When a field spans more than one octet, the order of bit values within each octet progressively increases as the octet number increases (network byte order). 0 1 2 3 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3
40、 4 5 6 7 0 1 2 3 4 5 6 7 Octet 0 Octet 1 Octet 2 Octet 3 Octets 4-7 Octet N-1Figure 2: Format convention ETSI ETSI TS 102 636-5-1 V1.1.1 (2011-02) 86 BTP packet structure As specified in TS 102 636-3 4, the BTP is used in the GeoNetwork protocol stack (TS 102 636-3 4, clause 7.3.2). A BTP packet sha
41、ll be comprised of the protocol headers and the payload as depicted in figure 3: The MAC header is the header of the MAC protocol of the ITS access technology. The MAC protocol can add additional protocol elements, such as a trailer for the MAC FCS as in ITS-G5 i.1. The GeoNetworking header is the h
42、eader of the GeoNetworking packet as defined in the present document and extended for media-dependent GeoNetworking functionality, such as for ITS-G5A specified in TS 102 636-4-2 i.3. The optional GeoNetworking security header. The BTP header is the header of the Basic Transport Protocol as defined
43、in the present document. The payload represents the user data that are created by upper protocol entities, i.e. the FL-SDU, and passed to the BTP entity for transmission. NOTE: The general packet structure is shown as seen by the MAC protocol of the ITS access technology layer. MAC Header GeoNetwork
44、ing Header GeoNetworking Security Header (optional) BTP header Payload (optional) Figure 3: BTP packet structure 7 BTP header 7.1 Overview BTP defines two protocol headers: BTP-A for interactive packet transport; and BTP-B for non-interactive packet transport. The headers are distinguished by the Ne
45、xt Header field in the GeoNetworking header i.2 as illustrated in table 1. Table 1: Encoding of BTP header types in the Next Header (NH) field of the GeoNetworking Common Header Next Header (NH) Encoding Description BTP-A 1 BTP-A headerBTP-B 2 BTP-B headerETSI ETSI TS 102 636-5-1 V1.1.1 (2011-02) 97
46、.2 BTP-A header 7.2.1 Structure of the BTP-A header The BTP-A header carries the source and the destination port (figure 4). The destination port identifies the protocol entity at the ITS Facility layer in the destination of a BTP-PDU. The source port indicates the port that the ITS Facility layer p
47、rotocol entity in the source has used to send the FL-SDU. The source port represents the port to which a reply to the BTP PDU should be addressed in the absence of other information. 0 1 2 3 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 Destination port Source port Figure 4: BTP-A
48、header format 7.2.2 Fields of the BTP-A header The BTP header shall carry the fields as specified in table 2. Table 2: Fields of BTP-A header Field # Field name Octet position Type Unit Description First Last 1 Destination port 0 1 16 bit integer Identifies the protocol entity at the destinations IT
49、S Facility layer. 2 Source port 2 3 16 bit integer Identifies the port of the protocol entity at the sources ITS Facility layer in the source of the BTP PDU. 7.3 BTP-B header 7.3.1 Structure of the BTP-B header The BTP-B header carries the destination port, but no source port (figure 5). The destination port identifies the protocol entity at the ITS Facility layer in the destination of a BTP-PDU. The destination protocol provides additional info if Destination port is a well-known
