1、 ETSI TS 102 295 V1.1.1 (2004-02)Technical Specification Satellite Earth Stations and Systems (SES);Broadband Satellite Multimedia (BSM)services and architectures;BSM Traffic ClassesETSI ETSI TS 102 295 V1.1.1 (2004-02) 2 Reference DTS/SES-00096 Keywords internet, IP, satellite, traffic ETSI 650 Rou
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6、dia. European Telecommunications Standards Institute 2004. All rights reserved. DECTTM, PLUGTESTSTM and UMTSTM are Trade Marks of ETSI registered for the benefit of its Members. TIPHONTMand the TIPHON logo are Trade Marks currently being registered by ETSI for the benefit of its Members. 3GPPTM is a
7、 Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. ETSI ETSI TS 102 295 V1.1.1 (2004-02) 3 Contents Intellectual Property Rights4 Foreword.4 Introduction 4 1 Scope 5 2 Void5 3 Abbreviations .5 4 Basis for the BSM traffic classes .6 4.1 Service cate
8、gories.6 4.2 ITU traffic classes 7 4.3 Pre-emption 8 5 BSM traffic classes.8 Annex A (informative): Bibliography.10 History 13 ETSI ETSI TS 102 295 V1.1.1 (2004-02) 4 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The info
9、rmation pertaining to these essential IPRs, if any, 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
10、 ETSI Secretariat. Latest updates are available on 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
11、000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Specification (TS) has been produced by ETSI Technical Committee Satellite Earth Stations and Systems (SES). Introduction The present document presents the
12、traffic classes that are going to be used to define and control Quality of Service (QoS) and Performance levels in a BSM. These classes are defined by the services operators who want to offer over BSM while being independent of the BSM implementation. In particular they do not depend on the system s
13、pecific priorities at the satellite dependant layers by rely on lower layer mapping function to ensure each traffic class is given appropriate quality of service. They are used by policy enforcement, queuing and resource allocation mechanisms to ensure that traffic entering the BSM is sorted and pro
14、cessed according to its characteristics. In order to characterize current and future Internet traffic flowing through the BSM, the classes contain both connection oriented and connectionless traffic classes. ETSI ETSI TS 102 295 V1.1.1 (2004-02) 5 1 Scope The scope of the present document is the def
15、inition of qualitative classes to sort the traffic entering the BSM according to generic class descriptors. The quantitative performance levels expected from a BSM link for each of these classes is beyond the scope of the present document. 2 Void 3 Abbreviations For the purposes of the present docum
16、ent, the following abbreviations apply: 3GPP Third Generation Partnership Project AF Assured Forwarding BSM Broadband Satellite Multimedia Diffserv Differentiated services (IETF) EF Expedited Forwarding IETF Internet Engineering Task Force IP Internet Protocol IPR Intellectual Property Rights ITU In
17、ternational Telecommunication Union ITU-R ITU-Radiocommunication sector ITU-T ITU-Telecommunication standardization sector MAC Medium Access Control MPLS MultiProtocol Label Switching OSPF Open Short Path First QoS Quality of Service RFC Request For Comments RSVP ReSerVation Protocol SI Satellite In
18、dependent SI-SAP Satellite Independent-Service Access Point TC ETSI Technical Committee TC Transfer Capability (ITU-T Recommendation Y.1221) TIPHON Telecommunications and Internet Protocol Harmonization over Networks TR Technical Report TS Technical Specification VoIP Voice over IP WG Working Group
19、VTC Video TeleConferencing PHB Per Hop Behaviour BE Best Effort EH Expedited Forwarding SLA Service Level Agreements ETSI ETSI TS 102 295 V1.1.1 (2004-02) 6 4 Basis for the BSM traffic classes 4.1 Service categories The BSM as any other broadband technology is going to offer a number of services tha
20、t require variable levels of delay, delay variation and loss in order to offer the appropriate quality of service see TR 101 984 and TR 101 985. Traffic classes are used to queue and police traffic but also to set Diffserv markings and negotiate transport level contracts across operators. TS 123 107
21、 and ITU have defined traffic classes that allow the BSM work to profit from solid heritage. The BSM traffic classes are defined at the SI-SAP interface as introduced in the BSM Functional Architecture TS 102 292. Clause 4 presents the basis for the definition of the BSM traffic classes. The applica
22、tions most likely to be offered over the BSM fall in the following categories: real time or conversational services such as voice and live video; non real time services relating to streaming (with caching) and web surfing; and traditional Internet traffic relating to email, newsnet etc. Figure 1 tak
23、en from the ITU-T Recommendation G.1010 gives an overview of these services based on error and delay tolerance. Figure 1: ITU-T Recommendation G.1010 mapping of BSM services to performance goals These service categories in turn define traffic classes when taking into account connectivity requirement
24、s and loss and jitter (delay variation) tolerance. Hence, the definition of BSM traffic classes follows general service category guidelines that have been used in the ITU, TS 123 107 and TS 101 329-2 (figure 2): type of traffic: connection oriented and connectionless; type of interaction: real time
25、interactive, interactive or non-interactive; and quality of service indicators: degree of acceptable loss, delay and delay variations. ETSI ETSI TS 102 295 V1.1.1 (2004-02) 7 Figure 2: Mapping of QoS requirements to class characteristics In addition to keep simple queues, minimize the number of queu
26、es and when appropriate limit switching hardware complexity, the number of classes should be kept fairly small and each class should represent the aggregate characteristics of fairly large flows. It is accepted in the BSM industry that at the IP level (above the SI “SAP“ interface) between 4 and 16
27、queues are manageable for different IP classes. Below the SI/SAP these classes can further be mapped into the satellite dependant priorities within the BSM which can be from 2 to 4 generally. 4.2 ITU traffic classes A recommendation of the TR 102 157 on Availability and Quality of Service was to fol
28、low the ITU-T Recommendation Y.1541 for traffic classes to define BSM specific classes. The ITU classes apply to international end-to-end IP network paths. It takes the 8 service categories defined in the previous clause and maps them onto 6 classes with 4 node mechanisms and recommendation for netw
29、ork techniques appropriate to each. In the context of the BSM, where only the BSM segment is of interest, the end to end approach of ITU-T Recommendation Y.1541 must be supplemented by BSM specifics like resource management mechanisms. ITU-T Recommendation Y.1541 provides an abstraction of the servi
30、ce category (see table 1) and concentrates on implementable and measurable quantity. In addition ITU-T Recommendation Y.1541 provides support to the signalling that is needed for QoS management (some traffic engineering messages for example) within a generic transactional class. It does not distingu
31、ish between fixed packet size (like voice) and variable packet size (data and video) applications but provides 2 level of QoS for real time conversational services. The ability to segregate fixed size packets (cells) could be used to better specify required network resources especially in those envi
32、ronments where flexible bandwidth management is available. Table 1: Guidance for IP QoS classes from the ITU-T Recommendation Y.1541 QoS class Applications (examples) Node mechanisms Network techniques 0 Real-Time, Jitter sensitive, high interaction (VoIP, VTC) Constrained Routing and Distance 1 Rea
33、l-Time, Jitter sensitive, interactive (VoIP, VTC). Separate Queue with preferential servicing, Traffic grooming Less constrained Routing and Distances 2 Transaction Data, Highly Interactive (Signalling) Constrained Routing and Distance 3 Transaction Data, Interactive Separate Queue, Drop priority Le
34、ss constrained Routing and Distances 4 Low Loss Only (Short Transactions, Bulk Data, Video Streaming) Long Queue, Drop priority Any route/path 5 Traditional Applications of Default IP Networks Separate Queue (lowest priority) Any route/path ETSI ETSI TS 102 295 V1.1.1 (2004-02) 8 In addition, the re
35、cent work in ITU-T has linked the ITU-T Recommendation Y.1541 traffic classes to the ITU-T Recommendation Y.1221 transfer capabilities. This in turn allows linking the BSM traffic classes to diffserv Per Hop Behaviour (PHB) (see table 2). Table 2: Y.1541 Classes, Y.1221 transfer capabilities and dif
36、ferentiated services Per Hop Behaviour (PHB) Adapted from ITU-T Recommendation Y.1221 transfer capability Associated differentiated services PHBs (RFC 2475 and RFC 2597) ITU-T Recommendation Y.1541 QoS class Best Effort (BE) Default Unspecified; Class 5 Under Study (new or modified capability) Assur
37、ed Forwarding (AF) Classes 2, 3, 4 Dedicated Bandwidth Expedited Forwarding (EH) Classes 0 and 1 When compared to the BSM QoS requirement however the ITU-RecommendationY.1541 is not fully compliant, hence the need for a specific BSM traffic class classification. 4.3 Pre-emption ITU-T Recommendation
38、Y.1541 has no provision for emergency messages and some time sensitive messages related to the essential time critical management of the BSM (neighbour discovery, times RSVP messages OSPF HELLO messages, etc.). Hence it was the recommendation of TR 102 157 to add a pre-emption class and provision fo
39、r variable size packets. The use of a pre-emption class is not unique to the BSM. All technologies that need to support voice and especially lifeline voice have more or less specified a traffic class that allow marked traffic to pre-empt any other reservation and get ahead in the queue. The pre-empt
40、ion (on admitted class) can be implemented at the level of call/session admission. Hence the pre-emption class could be supported at a higher layer. While there has been fairly little research on the impact of such a low traffic class on the QoS of impacted traffic (loss and or delay), some operator
41、s are reluctant to implement it mainly for legal reasons as it would violate some Service Level Agreements (SLAs). Both the Routing and Addressing TR 102 155 and the QoS TR 102 157 recommend a class that can access the BSM at any time, hence take the place of another SDU when necessary to access the
42、 satellite air interface. For the BSM a pre-emption class can be of two types: high quality connectionless class (but with constrained routing hence engineered paths as those message are most likely to have specific destinations) with low volume and high priority similar to the ITU class 2; or the h
43、ighest quality class (independent of connection type), a superclass “0“; this is the one that could be implemented at higher layers and not being visible at the IP Layer; however a mechanism must be envisaged to pass these packet to the BSM MAC with highest priority. The “pre-emption“ class should b
44、e tied to QoS signalling but could also be extended to IPv6 neighbour discovery, emergency messaging, essential routing messages, MPLS traffic engineering messages etc. as long as the overall traffic using the class remains a small percentage (nominally 1 % to 5%) of overall traffic. 5 BSM traffic c
45、lasses The proposed 8 traffic classes for the BSM are presented in table 3. They represent an adaptation of the ITU-T Recommendation Y.1541 classes at the SI-SAP using the ITU-T Recommendation G.1010 service categories and the BSM characteristics. In addition, they are also referring to the ITU-T Re
46、commendation Y.1221 Transfer Capabilities (TC) and differentiated services Per Hop Behaviour (PHB). The 8 classes (one of which is unassigned and leaves room for future expansion) can support most of the currently envisaged traffic over the BSM and allow for the convergence functions to quickly allo
47、cate and manage bandwidth. In addition it allows for simple mapping to and from the ITU-T classes. While it is still a possibility to use the ITU-T classes at the IP layer the definition of BSM specific classes at the SI-SAP will help overall BSM resource allocation, admission and congestion control
48、 and network management. ETSI ETSI TS 102 295 V1.1.1 (2004-02) 9 Table 3: BSM traffic classes BSM traffic class Service categories Node mechanisms BSM resource management (see note 1) Network techniques (informative only) Y.1541 class Y.1221 transfer capability PHB (see note 2) 0 Pre-emption, emerge
49、ncy services, essential network services Pre-empts any traffic that has allocated BSM bandwidth Strict admission control with pre-emption Strict admission control with pre-emption N/A N/A New Traffic Class EF 1 Real-Time, Jitter sensitive, high interaction Fixed size cells (VoIP) Separate queue with preferential servicing, traffic grooming, strictly admitted Dedicated or requested bandwidth Constrained routing and distance 0 Dedicated Bandwidth EF 2 Real-Time, Jitter sensitive, interactive - Variable size packets (Real Time Video) Separate queue with preferenti
