ATIS 1000627-2014 Broadband ISDN C ATM Layer Functionality and Specification.pdf

1、 ATIS-1000627.2014 Broadband ISDN ATM Layer Functionality and SpecificationAMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressing business priorities. T

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10、tute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer the service required from th

11、e Physical Layer (PHY); the interrelation with Layer Management; the encoding of the protocol data units; the protocol procedures. In specifying the service, it defines: the primitives and the resulting actions and events; the parameters and format associated with each primitive; interrelationship b

12、etween the primitives; valid sequence of primitives. The primitives and their associated parameters describe in an abstract manner the logical exchange of information between the ATM Layer and its service users (e.g., the ATM Adaptation Layer and the ATM Layer Management). They do not specify nor co

13、n- strain the implementation of entities or inter- faces. 2 Normative Reference The following standard contains provisions which, through reference in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are

14、 subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. ANSI T1.624-1993, Broadband ISDN User- Network Interfaces: Rates and Formats Specifications 1

15、ATIS-1000627.2014 3 Definitions 3.1 assigned cell: Cell that provides a service to an upper layer entity or ATM Layer Management entity (ATMM-entity). 3.2 asynchronous time division multiplexing: A multiplexing technique in which a transmission capability is organized in a priori unassigned time slo

16、ts. The time slots are assigned to cells upon request of each applications instantaneous real need. 3.3 Asynchronous Transfer Mode (ATM): A transfer mode in which the information is organized into cells. It is asynchronous in the sense that the recurrence of cells containing information from an indi

17、vidual user is not necessarily periodic. 3.4 ATM connection: A virtual channel connection (VCC) or a virtual path connection (VPC). 3.5 ATM Layer connection: An association established by the ATM Layer to support communication between two or more ATM service users (i.e., two or more next higher laye

18、r entities or two or more ATMM-entities). The communication over an ATM Layer connection may be either bidirectional or unidirectional. When bidirectional, two VCCs are used. When unidirectional, only one VCC is used. NOTE In the case where there is ATM Layer connection associated ATM Layer Manageme

19、nt (e.g., F5 Flow), the ATM Layer connection is bidirectional even if the user communication is unidirectional. 3.6 ATM Layer link: A section of an ATM Layer connection between two adjacent active ATM Layer entities (ATM-entities). 3.7 ATM link: A virtual path link (VPL) or a virtual channel link (V

20、CL). 3.8 ATM Traffic Descriptor: A generic list of traffic parameters that can be used to capture the intrinsic traffic characteristics of a requested ATM connection. 3.9 broadband: A service or system requiring transmission channels capable of supporting rates greater than the Integrated Services D

21、igital Network (ISDN) primary rate. 3.10 broadband access: An ISDN access capable of supporting one or more broadband services. 3.11 cell: ATM Layer protocol data unit (PDU). 3.12 cell delay variation:1) A quantification of variability in cell delay for a connection. 3.13 cell header: ATM Layer prot

22、ocol control information. 3.14 cell loss ratio:1) In a network, cell loss ratio is (1 x/y), where: y is the number of cells that arrive in an interval at the ingress of the network; and x is the number of these y cells that leave at the egress of the net- work. In a network element, cell loss ratio

23、is (1 x/y ), where: y is the number of cells that arrive in an interval at the ingress of the net- work element; and x is the number of these y cells that leave at the egress of the network element. 3.15 connection admission control:1) The procedure used to decide if a request for an ATM connection

24、can be accepted based on the attributes of both the requested connection and the existing connections. 3.16 Connection Endpoint (CE): A terminator at one end of a layer connection within a Service Access Point (SAP). 3.17 Connection Endpoint Identifier (CEI): Identifier of a CE that can be used to i

25、dentify the connection at a SAP. 3.18 corresponding entities: Peer entities with a lower layer connection among them. 2 ATIS-1000627.2014 3.19 demultiplexing: A function performed by a layer entity that identifies and separates SDUs from a single connection to more than one connection. 3.20 End Syst

26、em (ES): A system where an ATM connection is terminated or initiated. 3.21 fairness: As related to Generic Flow Control (GFC), fairness is defined as meeting all the agreed Quality of Service (QOS) requirements, by controlling the order of service for all active connections. 3.22 intermediate system

27、 (IS): A system that provides forwarding functions or relaying functions or both for a specific ATM connection. 3.23 layer entity: An active element within a layer. 3.24 layer function: A part of the activity of the layer entities. 3.25 layer service: A capability of a layer and the layers beneath i

28、t that is provided to the upper layer entities at the boundary between that layer and the next higher layer. 3.26 layer user data: Data transferred between corresponding entities, on behalf of 1) Corresponding network performance parameters are specified in ANSI T1.AI/93-029.the upper layer or layer

29、 management entities, for which they are providing services. 3.27 metasignaling: ATM Layer Management (LM) process that manages different types of signaling virtual channels (VCs), including the assignment, removal, and checking of VCs. 3.28 metasignaling VCs: The standardized VCs that convey metasi

30、gnaling information across a User-Network Interface (UNI). 3.29 multiplexing: A function within a layer that interleaves the information from multiple connections into one connection. 3.30 multipoint access: User access in which more than one terminal equipment (TE) is supported by a single network

31、termination. 3.31 multipoint connection: A connection with more than two endpoints. 3.32 Network Node Interface (NNI): The interface between two network nodes. 3.33 Operation and Maintenance (OAM) cell: A cell that contains ATM LM information. It does not form part of the upper layer information tra

32、nsfer. 3.34 peak cell rate: See 7.4.1. 3.35 peer entities: Entities within the same layer. 3.36 Physical Layer (PHY) connection: An association established by the PHY between two or more ATM-entities. A PHY connection consists of the concatenation of PHY links in order to provide an end-to-end trans

33、fer capability to PHY SAPs. 3.37 point-to-point connection: A connection with only two endpoints. 3.38 primitive: An abstract, implementation independent, interaction between a layer service user and a layer service provider. 3.39 protocol: A set of rules and formats (semantic and syntactic) that de

34、termines the communication behavior of layer entities in the performance of the layer functions. 3.30 protocol control information: Information exchanged between corresponding entities, using a lower layer connection, to coordinate their joint operation. 3.31 Protocol Data Unit (PDU): A unit of data

35、 specified in a layer protocol and consisting of protocol control information and layer user data. 3 ATIS-1000627.2014 3.32 relaying: A function of a layer by means of which a layer entity receives data from a corresponding entity and transmits it to another corresponding entity. 3.33 segment: A sin

36、gle ATM link or group of interconnected ATM links of an ATM connection. 3.34 semipermanent connection: A connection established via a service order or via network management. 3.35 Service Access Point (SAP): The point at which an entity of a layer provides services to its LM entity or to an entity o

37、f the next higher layer. 3.36 Service Data Unit (SDU): A unit of interface information whose identity is pre- served from one end of a layer connection to the other. 3.37 Source Traffic Descriptor: A set of traffic parameters belonging to the ATM Traffic Descriptor used during the connection setup t

38、o capture the intrinsic traffic characteristics of the connection requested by the source. 3.38 sublayer: A logical sub-division of a layer. 3.39 switched connection: A connection established via signaling. 3.40 traffic parameter: A parameter for specifying a particular traffic aspect of a connectio

39、n. 3.41 transfer capacity:1) The maximum sustainable rate of information transfer. 3.42 transit delay:1) The time difference between the instant at which the first bit of a PDU crosses one designated boundary, and the instant at which the last bit of the same PDU crosses a second designated boundary

40、. 3.43 unassigned cells: A cell identified by a standardized virtual path identifier (VPI) and virtual channel identifier (VCI) value, which has been generated and does not carry information from an application using the ATM Layer service. 3.44 Virtual Channel (VC): A communication channel that prov

41、ides for the sequential unidirectional transport of ATM cells. 3.45 Virtual Channel Connection (VCC): A concatenation of VCLs that extends between the points where the ATM service users access the ATM Layer. The points at which the ATM cell payload is passed to, or received from, the user of the ATM

42、 Layer (i.e., a higher layer or ATMM-entity) for processing, signify the endpoints of a VCC. VCCs are unidirectional. 3.46 Virtual Channel Link (VCL): A means of unidirectional transport of ATM cells between the point where a VCI value is assigned and the point where that value is translated or remo

43、ved. 3.47 virtual channel switch: A network element that connects VCLs. It terminates VPCs and translates VCI values. It is directed by Control Plane functions and relays the cells of a VC. 3.48 Virtual Path (VP): A unidirectional logical association or bundle of VCs. 3.49 Virtual Path Connection (V

44、PC): A concatenation of VPLs between virtual path Terminators (VPTs). VPCs are unidirectional. 3.50 Virtual Path Link (VPL): A means of unidirectional transport of ATM cells between the point where a VPI value is assigned and the point where that value is translated or removed. 3.51 virtual path swi

45、tch: A network element that connects VPLs. It translates VPI (not VCI) values and is directed by Control Plane functions. It relays the cells of the VP. 3.52 Virtual Path Terminator (VPT): A system that unbundles the VCs of a VP for independent processing of each VC. 4 ATIS-1000627.2014 4 Abbreviati

46、ons the primary role of the header is to identify cells belonging to the same connection on an asynchronous time division multiplex. The information field is transported transparently by the ATM Layer; no processing (e.g., error control) is performed on the information field at the ATM Layer. The he

47、ader size (5 octets) and the information field size (48 octets) are the same at all reference points, including User-Network Interface (UNI) and Network Node Interface (NNI), where the ATM technique is applied. Transfer capacity can be assigned on demand depending on the available resources. Cell se

48、quence integrity on an ATM connection is preserved. Sequency integrity implies that cells that originated at a connection endpoint shall be delivered at the destination endpoint in the same order in which they were originated. For an ATM connection, cells transmitted from an ATM link endpoint shall

49、arrive at any subsequent ATM link endpoint in the same order in which they were transmitted. The services provided by the ATM Layer are connection-oriented. Connection identifiers are assigned to each link of a connection when required, and released when no longer needed. Signaling and user information are carried on separate ATM Layer connections. 7 ATIS-1000627.2014 7 ATM Layer Model The functions of the ATM Layer are available to all services. Figure 1 shows the relation- ship between the ATM Layer and the layers in the B-ISDN PRM. The ATM Layer uses ATM connec