Tracing SS7 data packets

Use the ss7trace utility to trace SS7 data packets when monitoring or troubleshooting SS7 signaling. ss7trace displays any debug data tracing turned on through the command line interface or the SNMP interface. It does not accept commands; it only displays the tracing.

Note: In a configuration with redundant Signaling Servers, run ss7trace on the active Signaling Server to display live traffic tracing.

ss7trace is located in /opt/nmstx/bin.

Using ss7trace

To use ss7trace, follow these steps:

Step

Action

1

Enable tracing for MTP packets and ISUP packets as follows:

  • To trace MTP packets, enable MTP tracing and specify which component to trace by using the trace mtp command in the SS7 command line interface. For information, see trace mtp.

  • To trace ISUP packets, enable ISUP tracing and specify which component you want to trace by using the trace isup command in the SS7 command line interface. For information, see trace isup.

2

Use SSH to access the active Signaling Server, and log on as root.

3

Access the Dialogic environment shell:

bash

4

Start ss7trace by entering the following command:

ss7trace

Sample output

The output of ss7trace differs depending on the trace data. If MTP has data tracing on, ss7trace shows a hexadecimal display of all messages passed between MTP layer 2 and layer 3. If ISUP data tracing is on, ss7trace shows a hexadecimal display of all ISUP messages.

The following example shows the output generated for a single received packet followed by a single transmitted packet when both MTP and ISUP layer tracing are enabled. This example shows hexadecimal dumps of the actual packets sent and received. You must be familiar with the detailed encodings of ISUP or MTP packets to decode the trace data.

The packets in this example were collected from an ANSI configuration:

14:46:36.0 MTP3.1 <-- : Link # 1
85 01 00 00 02 00 00 05 06 00 01 00 20 01 0A 03 ............ ...
06 0B 03 C0 90 A2 05 03 10 01 01 01 0A 05 03 10 ................
04 22 04 00 00
 ."...           
14:46:36.0 ISUP.1 <-- 0.0.2:
06 00 01 00 20 01 0A 03 06 0B 03 C0 90 A2 05 03 .... ...........
10 01 01 01 0A 05 03 10 04 22 04 00             ........."..  

14:46:36.0 ISUP.1 --> 0.0.2:

06 00 06 14 14 00                               ......          

14:46:36.0 MTP3.1 --> : Link # 1

85 02 00 00 01 00 00 09 06 00 06 14 14 00 00    ...............

 

Note: The point code length in the routing label is different for ITU or Japan protocol variants.

The output of ss7trace contains the following sections:

Section

Description

MTP heading

Shows the following information:

  • Time the packet was sent or received.

  • Layer generating the trace.

  • Direction of the message (--> indicates a transmitted packet, <-- indicates a received packet).

  • Link number for the link on which the packet was sent or received.

MTP packet trace

Contains the content of the packet starting with the service information octet (SIO) followed by the routing label (DPC, OPC, and SLS). The data portion of the packet then follows.

ISUP heading

Shows the following information:

  • Time the packet was sent or received.

  • Direction of the message  (--> indicates a transmitted packet, <-- indicates a received packet).

  • Destination point code to which the packet was sent or from which it was received.

ISUP packet trace

ISUP portion of the packet being sent or received, starting with the circuit identification code (CIC), followed by the message type and parameters.