ATIS 1000118-1992 Signalling System Number 7 (SS7) C Intermediate Signalling Network Identification (ISNI).pdf

1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000118.1992(R2015) Signalling System Number 7 (SS7) Intermediate Signalling Network Identification (ISNI) As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industry

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11、isclaimer hence the term “constrained.” If this instruction is not followed, the message fails. As a message traverses a network indicated in the constrained routing information, this information is altered to indicate the network has now been traversed. 3.6 suggested routing information:2)If a mess

12、age entering an intermediate network includes suggested routing information, the suggested routing information recommends the next network in the message path. This instruction may or may not be followed. 3.7 notification information: The ISNI notification function delivers information about the net

13、work(s) transited by a message to the signalling node that terminates the signalling message. It allows the terminating Signalling End Point (SEP) to send any desired reply message(s) through the same (sequence of) intermediate network(s). The notification information consists of a list of network c

14、odes. This list could consist of a logged record of the actual networks transited by a signalling message (identification information) or it could be a list of networks that a particular network entity requests be traversed by the message (anticipation information). The list of network codes may or

15、may not include every network in the path, but will include enough information to fully determine the path. Notification information consists only of network codes as opposed to point codes for particular network nodes. 3.8 identification information: Identification information is a form of notifica

16、tion information that consists of the documentation of the actual sequence of intermediate networks traversed by a signalling message. The documentation of the sequence of networks traversed may also include the origination and destination networks. The documentation that the message traversed a giv

17、en network is performed by that network itself. Intermediate networks that are not ISNI-capable are not identified. ISNI identification information can be used to force a return error message, destined for the originating SEP, to transit the same intermediate network(s) as the original message. 3.9

18、anticipation information: Anticipation information is a form of notification information that consists of the documentation of the sequence of networks requested by some network entity. It is delivered to the destination SEP. Anticipation information differs from identification information in three

19、ways: a) it is placed in the message, in its entirety, by the origination network; b) it may or may not include information about all intermediate networks in the path that have the ISNI capability; c) it may include information about non-ISNI capable networks. 3.10 branch point: A branch point is a

20、 network point where two or more possible routes through different intermediate networks from the origination network to destination network physically diverge. A branch point may occur in any network except the destination network. 3.11 convergence point: A convergence point is a network point at w

21、hich two or more possible routes through different intermediate networks from the origination network to destination network converge. A convergence point may occur in any network except the origination network. A convergence point for a message transiting in one direction is a branch point for a me

22、ssage transiting in the opposite direction. 3.12 specification: Specification of a network occurs at the originating node when the application inserts the code(s) of the desired network(s) into the ISNI routing information in a message. This information will normally include the code of at least one

23、 selected network. 3.13 specification point: The specification point is the node in the originating network where specification occurs. 3.14 selected network: For a particular message path, any intermediate network between a branch point and a subsequent branch point or convergence point is a select

24、ed network. 3.15 explicit selection: Explicit selection of a network is an ISNI routing function. The explicit selection of a network is driven by the appearance of that networks code in the constrained routing information.3)3.16 selection point: The ISNI selection process occurs at a selection poin

25、t. The selection process provides the routing function that directs the message into a selected network. A selection point may or may not be a branch point. A branch point may not be required to be a selection point. 3.17 single selection scenario: The single selection scenario is defined by its phy

26、sical topology, which has exactly one branch point in the message path. An example is shown in figure 1. Note that one path from SEP X to SEP Y contains more than one intermediate network. However, once any one of the selected intermediate networks is chosen toward which the signalling message will

27、be forwarded (in an effort to send a signalling message from SEP X to SEP Y), the entire sequence of networks to be traversed is determined. If SEP X routes a signalling message to intermediate network C, the message must traverse intermediate network D to reach SEP Y. In accordance with the definit

28、ion of selection, the selection could be either implicit or explicit. The choice is to route the message to either: intermediate network A; intermediate network B, or; intermediate networks C and D. 3.18 multiple selection scenario:4) The multiple selection scenario is defined by its physical topolo

29、gy, which has more than one branch point in the message path. 4 Description of network capability 4.1 General description The ISNI capability provides the functionality to route non-circuit-related signalling messages through selected intermediate networks and the independent functionality to inform

30、 an application of the intermediate networks traversed by the message. The end user will interact with an end user service that may invoke the ISNI capability. The specific end user service that invokes ISNI is not within the scope of this capability description. 4.2 Procedures 4.2.1 Provision/withd

31、rawal From an end users viewpoint, services requiring specific intermediate network routing or notification, or both, can be realized through the use of ISNI. An end user cannot directly subscribe to ISNI, but may subscribe to an end user service that uses the ISNI capability. 4.2.2 Normal procedure

32、s 4.2.2.1 Activation/deactivation Activation/deactivation may be done either on a service-by-service basis or on a network basis in the origination and destination networks. Activation/deactivation is on a network basis in the intermediate network. 4.2.2.2 Invocation and operation Invocation and ope

33、ration of this network capability will be handled by the application process. 4.2.3 Exceptional procedures 4.2.3.1 Activation/deactivation None identified. 4.2.3.2 Invocation and operation None identified. 4.2.4 Alternate procedures 4.2.4.1 Activation/deactivation None identified. 4.2.4.2 Invocation

34、 and operation None identified. 4.3 Interworking considerations None identified. 4.4 Network capabilities for charging Not applicable. 4.5 Interactions with supplementary services Not applicable. 4.6 SDLs The SDL diagram for the user is shown in figure 2. 5 Functional capabilities and information fl

35、ows 5.1 Functional entity model The Intermediate Signalling Network Identification (ISNI) capability allows an application process in the origination network to specify a (sequence of) intermediate signalling network(s) for the purpose of routing a non-circuit-related signalling message and independ

36、ently to request that networks in the message path identify themselves to an application in the destination network. ISNI also allows the application process to send a list of intermediate signalling networks anticipated to be transited by the message to an application in the destination network. Th

37、e ISNI capability may be invoked by specific services. The specification of the (sequence of) intermediate network(s) will be determined by the origination network. If ISNI routing is used, the route is “constrained.” At each branch point in the end-to-end message path, where two or more possible ro

38、utes between the origination and destination network diverge, ISNI-constrained routing provides the capability to direct the message along one particular path.5)Constrained routing information, if present, will include the network(s) specified by the originating application and will allow ISNI-capab

39、le STPs in the message path to progress the message through the desired (sequence of) intermediate network(s). Notification information, if present, will carry the identity of one or more networks in the message path to the application receiving the message. This will allow the terminating applicati

40、on, if required, to return response messages along the same sequence of intermediate network(s), but in reverse order. The ISNI capability allows the transfer of non-circuit-related messages in the forward and backward directions through the same (sequence of) intermediate network(s). Referring to f

41、igure 1, if specification or anticipation information relating an intermediate network to a particular service exists, it must exist at signalling point X. In the single selection scenario, the originating application chooses among intermediate networks A or B or (C and D). If network C is chosen, t

42、hen the choice of D is determined. In this case, the ISNI notification information, if present, will convey the identity of network C or networks C and D. Similarly, if network D is chosen, then the choice of C is determined. In this case, the ISNI notification information, if present, will convey t

43、he identity of network D or networks C and D. If the originating application has set an option that requests “return of undelivered messages,” then, in the event of a routing failure, message return procedures shall be initiated. If constrained routing had been invoked, the message return shall be c

44、onstrained through the same (sequence of) network(s) in the reverse direction as used in the forward direction. 5.1.1 Description of origination network functional entity The origination network is a network that will invoke the ISNI capability. The origination network is the source of any constrain

45、ed routing information and any anticipation information. Should both pieces of ISNI information be included by the origination network, each will contain the network code of at least one selected network. Therefore, there may be some duplication in the information carried for the independent purpose

46、s of ISNI-constrained routing and anticipation. The origination network requires the use of a Signalling End Point (SEP) and may also require the use of Signal Transfer Points (STPs). 5.1.2 Description of destination network functional entity The destination network is a network that will terminate

47、incoming messages from an intermediate network and may route response messages based on the ISNI notification information received in the incoming message if the application requires it. The destination network includes an SEP and may also include STPs. 5.1.3 Description of intermediate network func

48、tional entity The intermediate network is a network used while routing non-circuit-related messages between origination and destination networks. For ISNI-constrained routing, the originating application specifies one or more intermediate networks. The selection process is the routing function that

49、directs the message through the branch point, toward the next specified network. If the constrained routing information specifies more than one intermediate network, ISNI-constrained routing will be used by ISNI-capable nodes to progress the message. Additional intermediate networks (not in the list) may also be determined as the result of implicit relationships between networks to eventually reach the destination network. If an intermediate network recognizes that identification is requested, it should insert its own network code in the message. An intermedi