Morneault, Ed. Pastor-Balbas, Ed. Please refer to the current edition of the "Internet Official Protocol Standards" STD 1 for the standardization state and status of this protocol. Distribution of this memo is unlimited. This document obsoletes RFC

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Morneault, Ed. Pastor-Balbas, Ed. Please refer to the current edition of the "Internet Official Protocol Standards" STD 1 for the standardization state and status of this protocol. Distribution of this memo is unlimited. This document obsoletes RFC M3UA Overview Protocol Architecture Native Management Functions Functional Areas Signalling Point Code Representation Routing Contexts and Routing Keys Routing Key Limitations Managing Routing Contexts and Routing Keys Message Distribution at the SGP Message Distribution at the ASP Signalling Gateway SS7 Layers Application Server IPSP Considerations Redundancy Models Application Server Redundancy Flow Control Congestion Management Sample Configuration Definition of M3UA Boundaries M3UA Protocol Elements Common Message Header M3UA Protocol Version: 8 bits unsigned integer Message Classes and Types Reserved: 8 Bits Message Length: Bits Unsigned Integer Variable-Length Parameter Format Transfer Messages ASP Up ASP Down Heartbeat BEAT ASP Active ASP Inactive Receipt of Primitives from the Layer Management AS States ASP Up Procedures ASP-Down Procedures ASP Active Procedures ASP Inactive Procedures Notify Procedures Heartbeat Procedures Routing Key Management Procedures [Optional] At an SGP At an ASP Single SG Configurations Multiple SG Configurations ASP Auditing MTP3 Restart NIF Not Available M3UA Version Control M3UA Termination Examples of M3UA Procedures Auditing Examples SG State: Unavailable Single Exchange Double Exchange Security Considerations IANA Considerations M3UA Port Number M3UA Protocol Extensions Document Contributors Normative References Informative References Signalling Network Architecture Signalling Gateway Redundancy The AS contains a set of one or more unique Application Server Processes, of which one or more is normally actively processing traffic.

Note that there is a relationship between an AS and a Routing Key. Failover - The capability to reroute signalling traffic as required to an alternate Application Server Process, or group of ASPs, within an Application Server in the event of failure or unavailability of a currently used Application Server Process.

Failover also applies upon the return to service of a previously unavailable Application Server Process. Layer Management - Layer Management is a nodal function that handles the inputs and outputs between the M3UA layer and a local management entity. Linkset - A number of signalling links that directly interconnect two signalling points, which are used as a module.

Network Byte Order - Most significant byte first, a. Routing Key - A Routing Key describes a set of SS7 parameters and parameter values that uniquely define the range of signalling traffic to be handled by a particular Application Server. Routing Context - A value that uniquely identifies a Routing Key. Routing Context values are configured either using a configuration management interface, or by using the routing key management procedures defined in this document.

It serves as an active, backup, load-sharing, or broadcast process of a Signalling Gateway. An SG contains a set of one or more unique Signalling Gateway Processes, of which one or more is normally actively processing traffic. Signalling Process - A process instance that uses M3UA to communicate with other signalling processes.

Stream - An SCTP stream; a unidirectional logical channel established from one SCTP endpoint to another associated SCTP endpoint, within which all user messages are delivered in-sequence except for those submitted to the unordered delivery service.

M3UA Overview 1. Protocol Architecture The framework architecture that has been defined for SCN signalling transport over IP [ 12 ] uses multiple components, including a common signalling transport protocol and an adaptation module to support the services expected by a particular SCN signalling protocol from its underlying protocol layer.

This is to take advantage of various SCTP features, such as: - Explicit packet-oriented delivery not stream-oriented - Sequenced delivery of user messages within multiple streams, with an option for order-of-arrival delivery of individual user messages - Optional multiplexing of user messages into SCTP datagrams - Network-level fault tolerance through support of multi-homing at either or both ends of an association - Resistance to flooding and masquerade attacks - Data segmentation to conform to discovered path MTU size Under certain scenarios, such as back-to-back connections without redundancy requirements, the SCTP functions above might not be a requirement, and TCP MAY be used as the underlying common transport protocol.

However, in the case where an ASP is connected to more than one SG, the M3UA layer at an ASP should maintain the status of configured SS7 destinations and route messages according to the availability and congestion status of the routes to these destinations via each SG. However, in the context of an SG, the maximum octet block size must be followed when interworking to a SS7 network that does not support the transfer of larger information blocks to the final destination.

Some configurations e. The M3UA layer at an ASP keeps the state of the routes to remote SS7 destinations and may initiate an audit of the availability and the restricted or the congested state of remote SS7 destinations. Functional Areas 1. In such a case, the SG could be addressable with a Point Code in each network appearance, and it represents a set of nodes in the IP domain into each SS7 network. Alias Point Codes [ 8 ] may also be used within an SG network appearance. Note: It is possible for the SGP Routing Key configuration data to be temporarily out of sync during configuration updates.

Inter-SGP protocol is outside of the scope of this document. The following example shows a signalling gateway partitioned into two network appearances.

Example with multiple network 1. Routing Contexts and Routing Keys 1. A Routing Key is essentially a set of SS7 parameters used to filter SS7 messages, whereas the Routing Context parameter is a 4-octet value integer that is associated to that Routing Key in a relationship.


MTP 3 User Adaptation Layer (M3UA)

There are multiple adaptation layers, each has its own purpose. M3ua is the most used layer. It works at the network layer level as per the OSI model. It also covers the general adaptation layer concepts. The protocol specification is given in RFC The simplest example is the point code.



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