IMG 1010 - Troubleshooting SS7 Links

This section describes common causes that prevent SS7 signaling links from coming into service or alignment.

Point code mismatch:

The OPC (Originating Point Code) as defined in the place holder must match the value that the distant end signaling point expects. Also, the distant end's point code must match the APC (Adjacent Point Code) and DPC (Destination Point Code) values.

Signaling link code mismatch:

The Signaling Link Code (SLC) is a number (0-15) which is assigned by both ends to identify a specific link within a link set. The SLC must match the SLC value assigned to the link by the distant end.

Network indicator mismatch:

The Network Indicator (NI) value is defined by two bits (therefore values 0-3 are possible). The default value of the Network Indicator is set to National (0x02) for both ANSI and ITU. Some networks may require the Network Indicator to be set to International (0x00) or one of the spare values (0x01 or 0x03). To change the NI value, see the IMG 1010 - SS7 Stack pane.

Following is an example SS7 trace showing a Network Indicator mismatch (NI is in bold).

The local stack is configured to a value of 2, and the remote switch is set to 3.

The network indicator codes are allocated as follows:

bits D C

0 0 (1) International network

0 1 (2) Spare (for international use only)

1 0 (3) National network

1 1 (4) Reserved for national use

Link status signaling unit size mismatch:

By default, the IMG's transmit a Link Status Signaling Unit (LSSU) with a 1-octet status field for both ITU and ANSI. Some signaling points may require a different LSSU size. If a different LSSU size is required, this can be accomplished by one of two ways:

• Send a raw API message to the IMG to change the setting. In order to accomplish this, a file needs to be created with the correct api hex digits. Contact our technical support personnel and they will assist you in creating the file to be sent to the IMG. For information on sending an API message to the IMG, see the following links:
  IMG 1010 - Raw API Commands
  IMG 1010 - Raw API Command
  IMG 1010 - Downloading a Raw File

• Changing the LSSU size can be accomplished by creating a new SS7 variant and sending it to the IMG. For information on how to create a new SS7 Variant or importing/exporting variants see the following links:
  IMG 1010 - Variant Entry
  IMG 1010 - Signaling Variant
  IMG 1010 - Creating Custom SS7 Variants

Path and rate problem:

A span carrying the signaling link must be configured for clear channel operation, in service, and not experiencing slips. Both parties must agree upon the timeslots used to carry the signaling link. Additionally, the data rate of the signaling link must be the same on both sides.

No route defined

A valid SS7 route must be defined to the destination to enable the IMG to send messages. This is typically indicated by received Signaling Link Testing Message (SLTM) with no SLTMs being sent by the IMG.