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1、INTERNATIONAL STANDARD ISO/IEC 15802-l First edition 1995-I l-01 Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Common specifications - Part 1: Medium Access Control (MAC) service definition Technologies de /information -
2、 T.4l.kommunications et bchange dinformation entre syskmes - RBseaux locaux et mbtropolitains - Spkcifications communes - Partie 1: DBfinition du ContrUe dacc b) the parameters associated with each primitive action and event, and the form they take; and 4 the interrelationship between, and the valid
3、 sequences of, these actions and events. The principal objectives of this part of ISO/IEC 15802 are 4 to specify the characteristics of a conceptual Medium Access Control Service; b) guide the development of Medium Access Control Protocols; and 4 guide the development of OSI protocols which make use
4、 of the MAC Service. This part of ISO/IEC 15802 does not specify individual implementation or products, nor does it constrain the implementation of Medium Access Control entities and interfaces within an information processing system. There is no conformance of equipment to this part of ISO/IEC 1580
5、2. Instead, conformance is achieved through implementation of conforming Medium Access Control Protocols that fulfil the Medium Access Control Service defined in this part of ISO/IEC 15802. 2 Normative references The following International Standards contain provisions which, through reference in th
6、is text, constitute provisions of this part of ISO/IEC 15802. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO/IEC 15802 are encouraged to investigate the possibility of applying the most recent
7、editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. ISO/IEC 7498-l : 1994, Information technology - Open Systems Interconnection - Basic Reference Model: The Basic Model. IS0 7498-3 : 1989, Information processing systems -
8、Open Systems Interconnection - Basic Reference Model - Part 3: Naming and addressing. ISOIIEC 10731 :1994, Information technology - Open Systems Interconnection - Basic Reference Model - Conventions for the definition of 0.51 services. Copyright International Organization for Standardization Provide
9、d by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 01:42:40 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 15802-l :1995(E) 0 ISO/IEC 3 Definitions For the purposes of this part of ISO/IEC 15802, the following
10、definitions apply. 3.1 Basic reference model definitions Although the MAC Service is not identified or defined in the OSI Basic Reference Model, this part of ISO/IEC 15802 is based on the concepts developed in the Basic Reference Model and makes use of the following terms defined in ISO/IEC 7498, as
11、 they might apply to the Medium Access Control Sublayer: 4 Entity b) Sublayer c) Service 4 Service-access-point e) Service-access-point-address f) Service-data-unit 0) Subnetwork address 3.2 Service conventions definitions Although the MAC Service is not identified or defined in the OSI Basic Refere
12、nce Model, this part of ISOAEC 15802 makes use of the following terms defined in ISO/IEC 10731, as they might apply to the Medium Access Control Sublayer: a) Servlce user b) Service provider c) Primitive 4 Request 4 Indication 3.3 MAC Service definitions 3.3.1 group-address; group-MSAP-address; grou
13、p Medium Access Control Service-access- point address: A value, otherwise valid as a Medium Access Control Setvice-access- point address, identifying a set of Medium Access Control Service-access-points, the set of end systems on which the identified Service-access-points are located being any subse
14、t of all stations on a particular local area network. NOTE - By contrast, the general definition of an (N)-address restricts the identified Service-access-point to a single open system. 4 Abbreviations LAN MAC MSAP MSDU OSI QOS OUI Local Area Network Medium Access Control Medium Access Control Servi
15、ce-access-point Medium Access Control Service-data-unit Open Systems interconnection Quality of Service Organizationally Unique Identifier Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04
16、/19/2007 01:42:40 MDTNo reproduction or networking permitted without license from IHS -,-,- 0 ISOAEC ISO/IEC 15902-l :1995(E) 5 Conventions 5.1 General considerations This part of ISO/IEC 15802 uses the descriptive conventions given in ISO/IEC 10731. The service model, service primitives, and time-s
17、equence diagrams used are entirely abstract descriptions; they do not represent a specification for implementation. 5.2 Parameters Service primitives, used to represent service user/service provider interactions (ISO/IEC 10731) convey parameters which indicate information available in the user/provi
18、der interaction, and have a global significance. The parameters which apply to each group of MAC Service primitives are set out in table 1. Each “X” in the table indicates that the primitive labelling the column in which it falls shall carry the parameter labelling the row in which it falls. Some en
19、tries are further qualified by items in parentheses. These are a) A parameter specific constraint: (=) indicates that the value supplied in an indication primitive is always identical to that supplied in a previous request primitive issued at the peer service-access-point. b) Indication that some no
20、te applies to the entry: (see note x) indicates that the referenced note contains additional information pertaining to the parameter and its use. In any particular interface, not all parameters need be explicitly stated. Some may be implicitly associated with the MSAP at which the primitive is issue
21、d, for example, an MA-UNITDATA.request need not include the source address parameter which may be associated with the MSAP at which the primitive is issued. 6 Overview of the MAC Service The MAC Service provides for the transparent transfer of data between MAC Service users. lt makes invisible to th
22、ese MAC Service users the way in which supporting communications resources are utilised to achieve this transfer, except when the MAC Service provider supports the MAC Service user specifying Routing Information. In particular, the MAC Service provides for the following: a) Independence of the under
23、lying MAC Sublayer and Physical Layer -the MAC Service relieves MAC Service users from all concerns, with the exception of QoS considerations, regarding which MAC technology is available. b) Transparency of transferred information - the MAC Service provides for the transparent transfer of MAC Servic
24、e user-data. lt does not restrict the content, format or coding of the information, nor does it ever need to interpret its structure or meaning. It may however restrict the maximum number of octets of MAC Service user-data that can be supplied in a user/provider interaction. c) Priority selection -
25、the MAC Service makes available to MAC Service users a means to request the transfer of data at a specified priority. d) Addressing - the MAC Service provides the means for the MAC Service user to identify itself and to specify the MSAP to which data is to be transferred. e) Routing Information -the
26、 MAC Service allows the user optionally to specify the route to the destination MSAP. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 01:42:40 MDTNo reproduction or networking
27、permitted without license from IHS -,-,- ISO/IEC 15802-l :1995(E) 0 ISO/IEC 7 Types of MAC Service Currently there is one type of MAC Service defined; the connectionless-mode MAC Service. 8 Features of the MAC Service The MAC Service provides the following features to the MAC Service user: a) A mean
28、s by which MSDUs of limited length are delimited and transparently transmitted from one source MSAP to a destination MSAP in a single MAC Service access, without establishing or later releasing a connection. b) Associated with each instance of connectionless-mode transmission certain measures of QoS
29、, which may be requested by the sending MAC Service user when the connectionless-mode transmission is initiated and may be modified by the MAC Service provider depending on the MAC technology. 9 Model of the MAC Service Although the MAC Service is not identified or defined in the OSI Basic Reference
30、 Model, this part of ISO/IEC 15802 uses the abstract model for a layer service defined in ISO/IEC 10731, clause 4 as it might apply to the MAC Sublayer. The model defines the interactions between the MAC Service users and the MAC Service provider which take place at the two MSAPs. Information is pas
31、sed between the MAC Service user and the MAC Service provider by service primitives, which may convey parameters. 9.1 Model of a MAC connectionless-mode transmission A defining characteristic of MAC connectionless-mode service - as provided between any two MSAPs - can be modelled in the abstract as
32、an association between the two MSAPs. This association is permanent. I I L _ _ _ _ _ AssociationtHwaenAandB- _ _ _ _ 1 MAC Service Provider Figure 3 - Model for a MAC Service Connectionless-mode Transmission Only one type of object, the unitdata object, can be handed over to the MAC Service provider
33、 via a MSAP. In figure 3, MAC Service user A represents the MAC Service user that passes objects to the MAC Service provider. MAC Service user B represents the MAC Service user that accepts objects from the MAC Service provider. 9.2 Service provided by the connectionless-mode MAC Service In general,
34、 the MAC Service provider may perform any or all of the following actions 4 discard objects; b) change the order of the objects. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 0
35、1:42:40 MDTNo reproduction or networking permitted without license from IHS -,-,- 0 ISOAEC ISO/IEC 15902-l :1995(E) The MAC Service exhibits a negligible rate of 4 object duplication; b) reordering of objects for a given priority. The operations that are performed by the MAC Service provider for a p
36、articular MAC association do not depend on the behaviour of the MAC Service users. Awareness of the characteristics of the MAC Sewice provided, e.g. the rate at which objects may be discarded, duplicated or miss-ordered is part of the MAC Service users a priori knowledge of the environment. 10 Quali
37、ty of connectionless-mode service The term “Quality of Service” (QoS) refers to certain characteristics of a connectionless-mode transmission as observed between the MSAPs. QoS describes aspects of a connectionless-mode transmission which are solely attributable to the MAC Service provider; it can o
38、nly be properly determined in the absence of MAC Service user behaviour (which is beyond the control of the MAC Service provider) that specifically constrains or impedes the performance of the MAC Service. Whether the view of the QoS during each instance of the use of connectionless-mode transmissio
39、n is the same to each MAC Service user associated with the service depends on the nature of their association and the type of information concerning the nature of the service made available to the MAC Service user(s) by the MAC Service provider prior to the invocation of the service. 10.1 Determinat
40、ion of QoS for connectionless-mode service A basic characteristic of a connectionless-mode service is that, unlike a connection-mode sewice, no dynamic association similar to that during a connection establishment is set up between the parties involved. Thus, characteristics of the service to be pro
41、vided during the transfer are not negotiated on a peer-to-peer basis. Associated with each MAC connectionless-mode transmission, certain measures of QoS are requested by the sending MAC Service user when the primitive action is initiated. The requested measures (or parameter values and options), are
42、 based on a priori knowledge by the MAC Service user of the service(s) made available to it by the MAC Service provider. Knowledge of the characteristics and type of sewice provided (i.e., the parameters, formats, and options that affect the transfer of data) is made available to a MAC Service user
43、through some layer management interaction prior to (any) invocation of the MAC connectionless-mode sewice. Thus, the MAC Service user not only has knowledge of the parties with which it may communicate, it also has explicit knowledge of the characteristics of the sewice it can expect to be provided
44、with for each invocation of the service. 10.2 Definition of connectionless-mode QoS parameters QoS parameters can be classified as 4 parameters that express MAC Service performance, for example . Transit Delay; . Residual Error Rate (corruption, duplication); . Probability of Lost Information. b) pa
45、rameters that express other MAC Service characteristics, for example . Priority. Some QoS parameters are defined in terms of the issuance of MAC Service primitives. Reference to a MAC Service primitive refers to the complete execution of that MAC Service primitive at the appropriate MSAP. Copyright
46、International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 01:42:40 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 15902-1:1995(E) 0 ISOAEC 10.2.1 Transit delay Tra
47、nsit delay is the elapsed time between MA-UNITDATA.request primitives and the corresponding MA- UNITDATA.indication primitives. Elapsed time values are calculated only on MSDUs that are transferred successfully. Successful transfer of a MSDU is defined to occur when the MSDU is transferred from the
48、sending MAC Service user to the intended receiving MAC Service user without error. For connectionless-mode transfer, transit delay is specified independently for each MAC connectionless-mode transmission. The transit delay for transfer of MSDUs between a given pair of MAC Service users is bounded, a
49、nd the value of this maximum transit delay is part of the 00s knowledge made available to the MAC Service users. 10.2.2 Residual error rate Residual error rate is the ratio of the number of MSDUs received containing undetected errors to the nurnber of MSDUs transferred across the MAC Service boundary during a measurement period. The relationship among these quantities is de