CSCF Network Tracing
Call Session Control Function

Contents

1Introduction
1.1Prerequisites

2
Tools
2.1NetTrace
2.2AppTrace and AppLog
2.3NetTraceCollector

3
NetTrace Function
3.1NetTrace Procedure
3.2Analysis of Trace Outputs

4
File Management

1   Introduction

This document describes the procedure that is to be used to obtain network traces from the Call Session Control Function (CSCF).

This document covers the following topics:

Note:  
Post-processing of machine-readable trace outputs is not included in this document.

1.1   Prerequisites

This section describes the prerequisites for this document.

To use this document, the user must be authorized to access CSCF with sudo/root privileges for the required actions.

1.1.1   Documents

Before starting this procedure, ensure that the following documents have been read:

1.1.2   Conditions

Certain troubleshooting activities can have an impact on node performance. For example, trace activation can be traffic disturbing and is not recommended without first consulting Ericsson. However, NetTrace can be activated for a few users and sessions without adversely affecting performance (up to 10 users is the recommended limit).

2   Tools

This section describes the tools that can be used for network tracing in the CSCF.

2.1   NetTrace

Note:  
The inherent problem with observing the behavior of a system by tracing is the consumed capacity of the tracing itself. If the cost is too high, it can interfere with the primary function of the system, at worst even causing system failure.

NetTrace is a tool that allows the user to trace transactions that traverse the CSCF depending on user-defined filter criteria. These transactions are formatted and output in standardized XML file format (in this document referred to as "machine readable") according to the 3GPP® specification Telecommunication management; Subscriber and equipment trace; Trace data definition and management.

Alternatively, traces can be read directly from the AppLog and AppTrace files (referred to as "human-readable"). Human-readable format of traces is proprietary and not specified by the TS 32.423.

It is possible to trace at two levels; Min (minimum) and Max (maximum) for both machine-readable and human-readable output formats.

When active, tracing is performed on all CSCF-implemented SIP interfaces and Standard Cx/Dx interfaces (except Push-Profile-Request (PPR)/Push-Profile-Answer (PPA), and Registration Termination Request (RTR)/Registration Termination Answer (RTA) when the Public User Identity is not included in the request message).

If CSCF nodes are collocated such as for ISP (I-CSCF S-CSCF P-CSCF) and IS (I-CSCF S-CSCF), signaling within a physical node is not traced unless there is a transition between the originating CSCF and the terminating CSCF or the opposite.

Descriptions for ieGroup name and ie name can be found in the TS 32.423.

The presence of an information element in the following tables is defined by the P (presence) column as follows:

The terms tracedPublicId1 and tracedPublicId2 used in the following tables refer to the Public User IDs that triggered the trace. The element tracedPublicId1 is always present as one Public User ID must have triggered the trace.

If the trace is triggered by more than one Public User ID, its output is as tracedPublicId2. For example, if a Public User ID is specified as an OrigPublicId, a different Public User ID is specified as a TermPublicId, and a session is set up between the users, both Public User IDs trigger in the same trace.

2.1.1   Machine-Readable SIP Output at Min Level

At Min Trace Level, the SIP transactions are represented by several XML tags. Limited information is output when tracing at this level.

For the standard XML elements included in output, refer to the 3GPP Specification Telecommunication management; Subscriber and equipment trace; Trace data definition and management.

The CSCF implemented data output is listed in Table 1 and Table 2.

Table 1    Machine-Readable SIP Output Request Data at Min Level

Request

ieGroup Name

ie Name

Presence

Comment

tracedPublicIds(1)

tracedPublicId1

M

A Public User ID that triggered tracing of this Request.

tracedPublicIds (1)

tracedPublicId2

O

A Public User ID that triggered tracing of this Request.

-

Request-Line

M

SIP Request line

Message Headers

To

M

SIP To header

Message Headers

From

M

SIP From header

Message Headers

Call-ID

M

SIP Call-ID header

Message Headers

CSeq

M

SIP CSeq header

(1)  ieGroup name tracedPublicIds is only output once, when the trace session is started.


Table 2    Machine-Readable SIP Output Response Data at Min Level

Response

ieGroup Name

ie Name

Presence

Comment

-

Status-Line

M

SIP Status line

Message Headers

To

M

SIP To header

Message Headers

From

M

SIP From header

Message Headers

Call-ID

M

SIP Call-ID header

Message Headers

CSeq

M

SIP CSeq header

2.1.2   Machine-Readable Cx Output at Min Level

At Min Trace Level, the Cx transactions are represented by several XML tags. Limited information is output when tracing at this level.

For the standard XML elements included in output, refer to the 3GPP specification Telecommunication management; Subscriber and equipment trace; Trace data definition and management.

The CSCF implemented data output is listed in Table 3 and Table 4.

Table 3    Machine-Readable Cx Output Command Data at Min Level

Command

ieGroup Name

ie Name

Presence

Comment

tracedPublicIds(1)

tracedPublicId1

M

A Public User ID that triggered tracing of this Command.

(1)  ieGroup name tracedPublicIds is only output once, when the Trace Session is started.


Table 4    Machine-Readable Cx Output Response Data at Min Level

Response

ieGroup Name

ie Name

Presence

Comment

-

Result-Code

O

Diameter Result-Code

-

Experimental-Result-Code

O

Diameter Experimental-Result-Code

Either Result-Code or Experimental-Result-Code is present.

Post-processing is required on the generated XML files to obtain meaningful trace data.

2.1.3   Human-Readable SIP Output at Min Level

At Min Trace Level, the SIP transactions are represented in plain-text form within the AppTrace. The Message Header and applicable parameters are included in output on individual lines. Limited information is included in output when tracing at this level.

The CSCF implemented data output is listed in Table 5 and Table 6.

Table 5    Human-Readable SIP Output Request Data at Min Level

Request

Message

Presence

Comment

traceSessionRef(1)

M

Indicates the forlop specified used by the operator

origPublicId (1)

M

The Originating Public User ID derived from this Request

termPublicId (1)

M

The Terminating Public User ID derived from this Request

tracedPublicId1 (1)

M

A Public User ID that triggered tracing of this Request

tracedPublicId2 (1)

O

A Public User ID that triggered tracing of this Request

Initiator

M

IP/Port/Transport that initiated this Request

Target

M

IP/Port/Transport that is the intended recipient of this Request

Request-Line

M

SIP Request line

To

M

SIP To header

From

M

SIP From header

Call-ID

M

SIP Call-ID header

CSeq

M

SIP CSeq header

(1)  These fields are only output once, when the trace session is started.


Table 6    Human-Readable SIP Output Response Data at Min Level

Response

Message

Presence

Comment

Initiator

M

IP/Port/Transport that initiated this Request

Target

M

IP/Port/Transport that is the intended recipient of this Request

Status-Line

M

SIP Status line

To

M

SIP To header

From

M

SIP From header

Call-ID

M

P Call-ID header

CSeq

M

SIP CSeq header

2.1.4   Human-Readable Cx Output at Min Level

At Min Trace Level, the Cx transactions are represented in plain-text form within the AppLog. The Command and Response and the Result-Code or Experimental-Result-Code AVP is included in output on individual lines. Limited information is included in output when tracing at this level.

The CSCF implemented data output is listed in Table 7 and Table 8.

Table 7    Human-Readable Cx Output Command Data at Min Level

Command

Message

Presence

Comment

Command-Name

M

Diameter Command Name

Table 8    Human-Readable Cx Output Response Data at Min Level

Response

Msg

Presence

Comment

Response-Name

M

Diameter Response Name

Result-Code

O

Diameter Result-Code

Experimental-Result-Code

O

Diameter Experimental-Result-Code

Either Result-Code or Experimental-Result-Code is present.

2.1.5   Machine-Readable SIP and Cx Output at Max Level

At Max Trace Level, the SIP and Cx transactions are encoded into hexadecimal and output as raw data in XML file format. In contrast to Min level, the complete contents of each request or command and response are output.

The mandatory data specified in Section 2.1.1 Machine-Readable SIP Output at Min Level and Section 2.1.2 Machine-Readable Cx Output at Min Level for Min level are also mandatory at Max level.

For the standard XML elements included in output, refer to the 3GPP Specification Telecommunication management; Subscriber and equipment trace; Trace data definition and management.

Post-processing is required on the generated XML files to obtain meaningful trace data.

2.1.6   Human-Readable SIP and Cx Output at Max Level

At Max Trace Level, the SIP and Cx transactions are represented in plain-text form within the AppLog. In contrast to Min level, the complete contents of each request or command and response are output.

The mandatory data specified in Section 2.1.3 Human-Readable SIP Output at Min Level and Section 2.1.4 Human-Readable Cx Output at Min Level for Min level are also mandatory at Max level.

2.2   AppTrace and AppLog

vDicos AppTrace is used to realize the NetTrace.

For a detailed description of AppTrace functionality, refer to AppTrace User Guide.

For machine-readable format, the AppTrace output must be directed to AppLog.

For human-readable format, the AppTrace output is to be directed to AppLog.

2.3   NetTraceCollector

The NetTraceCollector is a Perl-based script that collects trace data from the AppLog and outputs the data as in XML format.

3   NetTrace Function

The principle of NetTrace is to allow a user the possibility to log SIP and Cx transactions traversing the CSCF for fault finding and localization purposes.

Using the AppTrace, a trace session can be configured to trace SIP and Cx transactions based on the filtering of the Originating Public User IDs and Terminating Public User IDs for both Min and Max levels. The flow of actions required to obtain trace outputs for SIP and Cx is shown in Figure 1.

Figure 1   Simplified Flow Configuration and Use of NetTrace

3.1   NetTrace Procedure

3.1.1   Prepare and Start NetTrace

The following sequence is applicable when preparing and starting NetTrace for any type of trace output.

This procedure is valid when the user has direct access to the node.

For more information on how to ensure the XML files (if applicable) are output correctly, refer to IMS Common Components Troubleshooting Guide.

To prepare NetTrace for any type of trace output:

  1. Log on to the SC processor of the CSCF node:

    > ssh -A user1@<IP-address>

  2. Start the NetTraceCollector script (applicable for machine-readable only):
    1. Check if the NetTraceCollector script is already running by using, for example:

      > ps -ef | grep nettracecollector

    2. If the NetTraceCollector script is not running, start the script:

      > nettracecollector &

  3. Choose one of the following NetTrace output types:

3.1.2   Start NetTrace for Machine-Readable Output at Min Level

To specify the public users to trace and to make the trace output machine-readable (XML) at Min level:

  1. > CscfTrace –ro applog –user sip:user@domain –-forlop sip:user@domain=<forlop> --net_min_sip_method <sip method(s)> CSCFv_NetTraceMinMachineReadable_Trace_Profile

The following apply:

Note:  
It is possible to express multiple user IDs and multiple forlop values using command CscfTrace.

For more information, run CscfTrace –h. After starting trace, to see what process types and domains are enabled for the current session, run CscfTrace display.

3.1.3   Start NetTrace for Machine-Readable Output at Max Level

To specify the public users to trace and to make the trace output machine-readable (XML) at Max level:

  1. > CscfTrace –ro applog –user sip:user@domain –-forlop sip:user@domain=<forlop> CSCFv_NetTraceMaxMachineReadable_Trace_Profile

For more information on options, parameters, and CscfTrace, see Section 3.1.2 Start NetTrace for Machine-Readable Output at Min Level.

3.1.4   Start NetTrace for Human-Readable Output at Min Level

To specify the public users to trace and to make the trace output human-readable (read directly from AppLog) at Min level:

  1. > CscfTrace –ro applog –user sip:user@domain –-forlop sip:user@domain=<forlop> --net_min_sip_method <sip method(s)> CSCFv_NetTraceMinHumanReadable_Trace_Profile

For more information on options, parameters, and CscfTrace, see Section 3.1.2 Start NetTrace for Machine-Readable Output at Min Level.

3.1.5   Start NetTrace for Human-Readable Output at Max Level

To specify the public users to trace and to make the trace output human-readable (read directly from AppLog) at Max level:

  1. > CscfTrace –ro applog –user sip:user@domain –-forlop sip:user@domain=<forlop> CSCFv_NetTraceMaxHumanReadable_Trace_Profile

For more information on options, parameters, and CscfTrace, see Section 3.1.2 Start NetTrace for Machine-Readable Output at Min Level.

3.1.6   Stop NetTrace

To stop NetTrace:

  1. > CscfTrace stop

3.2   Analysis of Trace Outputs

3.2.1   Machine-Readable Traces

NetTrace XML files are located in the following directory in CSCF node:

/storage/no-backup/cmco_utils-cxp9020686/nettrace/cscf

The following naming convention applies to an XML file that is being created:

A<date>.<time>-CSCF.<nodeName>.<TraceReference>.<SessionRef>.xml.COMPLETE

Where:

For example:

A20110128.1609-CSCF.ManagedElement1.1111.56032.xml

Post-processing is required by a system compliant with the TS 32.423.

After an XML file is completed and ready for post-processing, the suffix .COMPLETE is appended to the filename.

For example:

A20110128.1609-CSCF.ManagedElement1.1111.56032.xml.COMPLETE

NetTrace XML files can be fetched using File Management. For more information, see Section 4 File Management.

3.2.2   Human-Readable Traces at Min Level

Trace outputs are located in the AppLog, /storage/no-backup/coremw/var/log/saflog/AppTrace_*.log. The user locates the so called "start" message, which is a line with the ims.cscf.netio.info domain and Msg: “traceSessionRef: <TraceReference>" where the <TraceReference> is the forlop defined by the user, for example:

...pid:581 forlop:237897 id:"ims.cscf.netio.info" MsgLength:"123" Msg:"traceSessionRef: 1234"

The TraceReference in this case is "1234".

This line is followed by three more AppTrace lines containing the origPublicId, termPublicId, and tracedPublicIds, for example:

...pid:581 id:"ims.cscf.netio.info" forlop:237897 ...MsgLength:"102" Msg:"origPublicId: sip:user_a@cscf.com"
...pid:581 id:"ims.cscf.netio.info" forlop:237897 ...MsgLength:"69" Msg:"termPublicId: sip:user_a@cscf.com"
...pid:581 id:"ims.cscf.netio.info" forlop:237897 ...MsgLength:"36" Msg:"tracedPublicId1: sip:user_a@cscf.com"

The forlop, "237897" represents a session that has been traced (associated with TraceReference 1234). Any line that contains "forlop: 237897" represents a header of a traced message or response from the same session, for example:

...pid:581 id:"ims.cscf.netio.sip.register" forlop:237897 ...MsgLength:"130" Msg:"REGISTER sip:cscf.com"
...pid:581 id:"ims.cscf.netio.sip.register" forlop:237897 ...MsgLength:"109" Msg:"To: <sip:user_a@cscf.com>"
...pid:581 id:"ims.cscf.netio.sip.register" forlop:237897 ...MsgLength:"84" Msg:"From: <sip:user_a@cscf.com>
...pid:581 id:"ims.cscf.netio.sip.register" forlop:237897 ...MsgLength:"57" Msg:"Call-ID: 18be-147-67840"
...pid:581 id:"ims.cscf.netio.sip.register" forlop:237897 ...MsgLength:"20" Msg:"CSeq: 12271 REGISTER"
...pid:186 id:"ims.cscf.netio.dia.cx" forlop:237897 ...MsgLength:"85" Msg:" Name: User-Authorization-Answer"
...pid:186 id:"ms.cscf.netio.dia.cx" forlop:237897 ...MsgLength:"62" Msg:" AVP: Result-Code 2001”

3.2.3   Human-Readable Traces at Max Level

Trace outputs at this level follow the same principle as those at Min level. The user locates the "start" message as for Min level, notes the forlop, and finds the corresponding lines that represent the session.

The only difference when locating the lines for headers at Max level is that the trace domains are ims.sip.netio.rx, ims.sip.netio.rx, ims.diaif.netio.rx, and ims.diaif.netio.rx.

4   File Management

The CSCF Network Tracing XML files are exposed by File Management in the following file group structure:

For more information on file groups, refer to Handling Files.



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