Dialogic IMG - How to configure SS7 A Links on a Dialogic Integrated Media Gateway (IMG)
Prerequisites
The reader should be familiar with the structure of SS7 networks, SS7 protocols and SS7 terminology.
This article also assumes that the reader is familiar with configuration of a Dialogic IMG Integrated Media Gateway (IMG).
Before configuring the SS7 links, the TDM links (T1 or E1) that will carry the SS7 links must be configured.
Procedure
The IMG functions as an SSP and supports both A and F links.
This procedure describes the steps required to configure an SS7 A link on the IMG.
The following example configuration shows the steps required to configure two linksets to redundant STPs, configure redundant links to each STP, and configure the SS7 routes to the STPs and DPC. Note that “IMG 1010” refers to a Dialogic IMG 1010 Integrated Media Gateway.
The following information will be needed prior to starting the configuration:
The SS7 Point Codes (OPC, APC and DPC)
The T1 or E1 span that the SS7 link(s) will be on, and the timeslot the link is on.
The ISUP variant that will be used (ANSI, ITU, ETSI, other)
The Network Indicator
• 0 - International Network
• 1 - Spare (for international Network)
• 2 - National Network
• 3 - Spare (for National Network)
Before being able to configure the SS7 stack, you will need to configure the T1 or E1 spans that will be used for the SS7 links.
1. Configure the SS7 Stack. Select the ISUP variant, enter the OPC, and verify the remaining parameters (Cause Location, Exchange Type, Network Indicator, etc.)
2. Configure the SS7 linkset for STP 1.
a) ClientView will automatically populate the Links Set ID with the next available ID
b) Enter the APC of the STP.
3. Configure the SS7 linkset for STP 2.
a) ClientView will automatically populate the Links Set ID with the next available ID
b) Enter the APC of the STP.
4. In Linkset 1 configure SS7 route to STP 1.
a) Set the Route type to NEW
b) Set the Priority to a number > 1
5. In Linkset 2 configure SS7 route to STP 2
a) Set the Route type to NEW
b) Set the Priority to a number > 1
6. In Linkset 2, configure the cross route to STP 1
a) Set the Route type to Existing (Combined Linkset Disabled)
b) Set the Priority to a value greater than 0, but less than the value set in step 4.
7. In Linkset 1, configure the cross route to STP 2
a) Set the Route type to Existing (Combined Linkset Disabled)
b) Set the Priority to a value greater than 0, but less than the value set in step 5.
8. In Linkset 1, configure the SS7 link to STP 1. Verify that the SS7 link comes into service
9. In Linkset 2, configure the SS7 link to STP 2. Verify that the SS7 link comes into service
10. Configure an SS7 Route to the DPC in Linkset 1
a) Set the Route type to New
b) Set the Priority to 0
11. Configure an SS7 Route to the same DPC in Linkset 2
a) Set the Route type to Existing (Combined Linkset enabled), and select the point code of the DPC.
b) Set the Priority to 0
Repeat steps 10 and 11 for each DPC connected via these STPs.
SS7 Route notes
1. In the Priority field, select the priority to assign to the route when there are multiple routes to the same destination (valid range: 0 - 35).
2. A primary (new route) exists for every destination.
3. Signaling traffic is routed over available linksets according to the route priority. 0 is the lowest priority, 35 is the highest priority.
4. Linksets with the same priority to a destination load share traffic as a combined linkset.
5. The Priority field will be disabled when the route type is set to ‘Existing Route (Combined Link Set Enabled)’ because all routes within the combined linkset will have the same priority.
6. Route Type:
a) New Route – First route to destination.
b) Combined Linkset Disabled – Used for cross routes to STP.
c) Combined Linkset Enabled – Used for cross route to DPC.
7. A Route must be configured in the linkset for each STP and each DPC.
Glossary of Acronyms / Terms
Service Switching Points (SSPs)
• SSPs are PSTN switches that originate or terminate calls, or route calls to other switches (tandem switches)
• SSPs exchange SS7 messages to set up, manage and release voice circuits
Service Control Points (SCPs)
• SCPs are database servers that respond to requests from SSPs for call routing information
Signal Transfer Points (STPs)
• STPs are packet switches that serve as routers in the SS7 network
• Incoming SS7 messages are switched to outgoing links based on routing information contained in the messages (not just based on the destination )
A Link:
• An A (Access) link connects a signaling end point (e.g., an SCP or SSP) to an STP.
F Link:
• An F (fully associated) link connects two signaling end point (SSPs).
OPC - Originating Point Code
DPC - Destination Point Code
APC - Adjacent Point Code