Sigtran / M3UA

Owned by Kelli Higdon
Last updated: Apr 02, 2024
6 min read

 

 

 

IMG 2020 used in AS Mode (Application Server)

The diagram below demonstrates the IMG 2020 used as an Application Server (AS). Using the IMG 2020 as an Application Server will enable the IMG 2020 to be used in a Next Generation SS7 interconnect utilizing IP for SS7 signaling as an alternative to MTP2 based signaling links. The diagram below displays the use of the IMG 2020 as a replacement for conventional MTP2 signaling links. The IMG 2020 utilizes the IP network to pass ISUP signaling over associations. The term associations is used instead of links within Sigtran networks. In the WebHelp, the term Sigtran or St-link and the term associations are used, but all have the same meaning. The CICs in the diagram are controlled over these associations. This is one of the ways in which the IMG 2020 can be used as an Application Server. The information below explains the basic functionality of the IMG 2020 when used as an Application Server which will communicate with an External Signaling Gateway such as the Dialogic® DSI Signaling Gateway. Please note that the CICs shown are running over TDM, but the Sigtran signaling runs over IP associations.

  • Each stack configured as an Application Server will support communicating with up to (16) Remote Signaling Gateway Stacks.

  • The IMG 2020 can be configured in a standalone or redundant configuration.

  • An SS7 stack configured as an Application Server does not support being configured as a Signaling Gateway Stack as well.

  • A stack configured as an Application Server does not support configuring conventional SS7 links etc. on that same stack.

  • The M3UA Application Server is license supports up to four stacks. One M3UA license will support creating one, two, three, or four stacks configured for M3UA signaling.

  • The associations are licensed in two associations. Licenses range from 2 associations up to 64 associations on a Standalone system.

  • In the diagram above the External Signaling Gateway cannot be a IMG 2020. In this example, the IMG 2020 does not support SCCP traffic.

  • Sharing M3UA-ASP's by one SS7 signaling stack is NOT supported (ASP Multiplexing).

  • M3UA ASP does NOT support broadcast traffic.

  • The IMG 2020 Application Stack supports DPC routing to its Remote Signaling Gateways.

Interworking of Sigtran AS and SIP

One of the valuable aspects of the IMG 2020 is in its "Any to Any" Signaling capabilities, where one protocol can interwork with another. When used on TDM networks, the IMG 2020 can be used to interwork between TDM protocols (notably SS7 ISUP and ISDN PRI) and IP protocols (notably SIP, but also including SIP-I, SIP-T and H.323). For the case where the IMG 2020 is configured to take on the Sigtran AS role, the IMG 2020 will terminate an SS7 ISUP session which is layered upon the Sigtran M3UA adaption layer and then the ISUP messages can be interworked with the SIP protocol. This approach uses the same standards and conventions which the IMG 2020 uses for SS7 to ISUP interworking cases where the ISUP messages are transported over the TDM network.

The diagram below shows how this can work:

IMG 2020 used in SG Mode (Signaling Gateway)

The diagram below demonstrates the IMG 2020 being used as a Signaling Gateway (SG) and is part of an entry level Signaling Switching Point implementation. The diagram displays a conventional SS7 network sending traditional MTP3 traffic to the IMG 2020 that is in operation as a Signaling Gateway. The IMG 2020 provides the Nodal Interworking Function/Routing Layer that allows SCCP signaling to be inter-worked into the M3UA/IP Network. There are limitations when configuring the IMG 2020 as a Signaling Gateway. See items below for information on functionality and limitations.

  • A maximum for (4) M3UA application servers can be connected to the IMG 2020 that is configured as a Signaling Gateway.

  • Any application servers connected as displayed in the configuration above must support SCCP traffic.

  • The IMG 2020 that is configured as an Application Server as depicted in the diagram above is not supported. In the scenario above, the IMG 2020 does not support ISUP traffic.

  • The IMG 2020 SG only supports SCCP traffic between MTP and M3UA networks, SCCP traffic between AS’s are not allowed.

  • The Nodal Interworking Function will permit SCCP user part with Subsystem routing to and from the Application Server.

  • The M3UA Application Server license supports up to four stacks. One M3UA license will support creating one, two, three, or four stacks configured for M3UA signaling.

  • The IMG 2020 node configured as a SG will share a common point code with a set of M3UA-based application servers.

  • The IMG 2020 configured as a Signaling Server can support up to 64 associations on a standalone system and 128 associations on a Redundant System.

  • Sharing M3UA-SGP's by one SS7 signaling stack is supported (SGP Multiplexing).

  • The IMG 2020 can be configured in a standalone or redundant configuration.

Redundant Node Information

When configuring the IMG 2020 as either an Application Server or a Signaling Gateway in an M3UA network, the outbound signaling traffic can be shared between two IMG 2020's when they are set up in a redundant node scenario. In this scenario (displayed below), the signaling traffic on the outbound side can be distributed evenly over each IMG 2020. To accomplish load sharing, the primary node as well as the secondary node must have an association routed to each remote gateway. The diagram below displays the IMG 2020's configured as an SS7 redundant node pair.

Redundant Node Selection (Redundant SS7 server configuration only)

  • If routing is available to the remote destination (DPC) using an association on the current active SS7 server node, all traffic will originate from the associations configured on the active SS7 server node and route through the Signaling Gateway to the remote destination (DPC).

  • If the remote destination (DPC) is not accessible through the currently active SS7 server node route but there is accessibility to the destination (DPC) through a Signaling Gateway route on the current standby SS7 server node, all traffic will originate from the associations configured on the standby server node.

Signaling Gateway Selection

  • Of the currently provisioned Signaling Gateway routes to the destination (DPC), a list is formed including all the currently accessible Signaling Gateway routes to that destination (DPC). If the list contains two or more Signaling Gateway routes to the destination (DPC), half the traffic is directed toward the first Signaling Gateway route while the remaining traffic is directed toward the second Signaling Gateway route. No traffic is directed toward subsequent Signaling Gateway routes if the list contains more than two routes.

  • If the list contains only one Signaling Gateway route, all traffic is directed to that Signaling Gateway.

Association selection

  • Of the currently provisioned associations to the Signaling Gateway, a list is formed including the currently active associations routed to that particular Signaling Gateway. If that list contains two or more associations to that Signaling Gateway, the Signaling Gateway traffic is divided as evenly as possible (within the granularity of SLS) among the associations.

  • If that list contains only one association, all traffic to that Signaling Gateway will be directed toward that association.

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