TSP Lab	GTPCAssembler - GTP-C CDR Assembler module	GTPCAssembler

The GTP-C CDR Assembler module
`("GTPCAssembler")`

Basic Operation
User interface
Views
Types of GTP records
Configuration
Version history

Basic Operation

Receives Storage2 format GTP messages from the Internet and Transport Layer Reassembler module through a TCP/IP connection
Selects the GTPv0 and GTPv1 and GTPv2 control messages to process
Compiles GTP transactions based on the Sequence Number and the Source-IP:port+Destination-IP:port parameters
Maintains GTPv1 contexts and GTPv2 sessions based on the assembled transactions
Handles SRVCC transactions and creates Sv-related records to follow SRVCC activities (a similar method is used for GTPv1 Forward Relocation transactions)
Forwards transactions and contexts to the CDR Writer module
Forwards 'GTPv0 Create PDP Context', 'GTPv1 Create PDP Context' and 'GTPv2 Create Session' transactions to the GTP Statistics module to create statistics about the PDP/Session activations
Operation can be followed on the screen by the counters
Logs counters quarter-hourly and print out in CSV format

Collection of SRVCC transactions

The SRVCC procedure related GTPv2 control messages are collected into transactions based on the Sequence Number and the Source-IP:port+Destination-IP:port parameters. "SRVCC CS to PS" and "SRVCC PS to CS" transactions and the related "SRVCC CS to PS Complete/Cancel" or "SRVCC PS to CS Complete/Cancel" transactions are combined into "Sv-summary" records which are written into CDRs with the messages.
These summary records contain the following values:

type
- PS to CS
- CS to PS
opening reason (normal, incomplete)
- normal - the summary record was opened by an "SRVCC CS to PS" or an "SRVCC PS to CS" transaction
- incomplete - the summary record was opened by an an "SRVCC CS to PS Complete/Cancel" or an "SRVCC PS to CS Complete/Cancel" transaction without an antecedent "SRVCC CS to PS" or "SRVCC PS to CS" transaction
closing reason (complete, cancel, timed out)
- complete - the event ended in an "SRVCC CS to PS Complete" or an "SRVCC PS to CS Complete" transaction
- cancel - the event ended in an "SRVCC CS to PS Cancel" or an "SRVCC PS to CS Cancel" transaction
- timed out - a "Complete" or "Cancel" transaction did not arrived within the defined time out value
- rejected - the opening transaction was rejected
IMSI, IMEISV, C-MSISDN (displayed as MSISDN), STN-SR and the Source endpoint values
Start date & time - time stamp of the first message of the opening transaction
End date & time - time stamp of the last message of the closing transaction
Total duration - difference of End date & time and Start date & time
Details of the messages belonging to the transactions

IMSI, MSISDN and IMEI are derived for transactions which do not contain these pieces of information and indicated by a question mark in the CDR at the end of the parameter.

User Interface

The main menu

Menu	Menu item	Meaning
[File]
	Load state	Load a previously saved memory dump
	Save state	Save the memory content into a dump file (both context and open transaction statistics memories)
	Log counters	Save counters into log file
	Save counters	Save counters into CSV file
	Exit	Shuts down the program
[Tools]
	Start processing	Enable data processing
	Stop processing	Disable processing
	Clear state	Reset internal states to the initial values
	Flush state	Send messages from internal buffers to output channels
	Clear counters	Reset counters to zero
	Settings	Set INI file settings from menu
	Save settings	Save current settings into the INI file
[Help]
	Help	Currently not used
	About	Show information about the program

The bottom status-line

Current state of processing: acitve or inactive
Indication of the state of internal memories
Uptime: time elapsed since module has been started up

The "Log" tab

The "Log" view shows the latest log lines on the screen with their timestamps. The counters of the views are logged every quarter hour. The log level can be set through a drop-down list (Off, Normal, Detailed, Debug), the initial level is defined in the INI file. If the INI file does not exist (first-start without INI file), the default value is 'Normal'.

To search in the log entries, there is a 'Find' text-field. The 'next' button applies the text search and jumps to the next match.

Each log entry has a category, which is represented by the following icons:

Information about the operation
Warning: a probably unplanned event occurred
Error: an unplanned error during operation

The "GTP-C Assembler" tab

Sections in views can be collapsed and expanded using the triangle button at the right up corner of the sections.

Counters in the "Incoming messages" section

Message time: The current message time in GMT
Incoming messages: The count of all the incoming datagrams
GTP-C messages: The count of the incoming, validated GTP-C messages
GTP-C invalid messages: The count of the incoming, invalid messages
Non GTP-C messages: The count of the incoming, non GTP messages

Counters in the "GTP-C Assembler overview" section

Processing speed: The ratio of the message time and the system time
CDRs with IMSI ratio: The IMSI attachment ration
Transaction timeout ratio: The transaction timeout ratio
Transaction failure ratio: The transaction failure ratio
Successful subscriber lookup ratio: The ratio of the successful subscriber lookups
Successful TEID lookup ratio: The ratio of the successful TEID lookups

Counters in the "Transaction details" section

Active transactions: The count of the active transactions
Opened transactions: The count of the opened transactions
Accepted transactions: The count of the closed transactions
Failed transactions: The count of the failed transactions
Timed out transactions: The count of the timed out transactions

Counters in the "Session/Context details" section

Active sessions/contexts: The count of the active sessions or contexts
Active subscribers: The count of the subscribers
Active TEIDs: The count of the active endpoints
Normally opened sessions/contexts: The count of the normally opened sessions or contexts
Incompletely opened sessions/contexts: The count of the incompletely opened sessions or contexts
Normally closed sessions/contexts: The count of the normally closed sessions/contexts
Overlapped sessions/contexts: The count of the overlapped sessions or contexts
Timed out sessions/contexts: The count of the timed out sessions or contexts
Overlapped TEIDs: The count of the overlapped TEIDs
TEID registry failures: The count of the failed TEID registrations or unregistrations
NSAPI/EBI registry failures: The count of the failed NSAPI/EBI registrations or unregistrations

Counters in the "Forward relocation details" section

Active forward relocations: The count of the active forward relocations
Relocations with IMSI: The count of the relocations with IMSI
Relocations without IMSI: The count of the relocations without IMSI
Relocations without active user: The count of the relocations without active user

Counters in the "CDR database details" section

Transaction record time: The current transaction record time
Active sessions/contexts: The count of the active transactions
Active subscribers: The count of the active subscribers
Messages written: The count of the outgoing messages
Transactions written: The count of the outgoing transaction records
Sessions/Contexts written: The count of the outgoing session/context records
Periodic Sessions/Contexts written: The count of the outgoing periodic session/context records
Session/Context lookup failure: The count of the failed session/context id lookups
Subscriber lookup failure: The count of the failed subscriber lookups

The "Sv Assembler" tab

Sections in views can be collapsed and expanded using the triangle button at the right up corner of the sections.

Counters in the "Sv details" section

CDRs with IMSI ratio: The IMSI attachment ratio
Active subscribers: The count of the subscribers
Messages written: The count of the outgoing messages
Transactions written: The count of the outgoing transaction records

The "Connections" tab

This view shows the currently used inputs and outputs. Both input and output can be defined in INI file before starting the program, as well as during operation. Details of connections can be collapsed and expanded using the "expand" triangle button on the right side of the connections.

Incoming message time: The time of the last incoming message
Incoming bytes: The count of the incoming bytes
Incoming messages: The count of the incoming messages
Incoming sorter state: The incoming message sorted state
Outgoing message time: The time of the last outgoing message
Outgoing bytes: The count of the outgoing bytes
Outgoing messages: The count of the outgoing messages
Outgoing sorter state: The outgoing message sorted state

Controls of Input and Output connections

"New" button (): opens the 'Create connection' dialogue window
"Recent" button (): opens the list of the recently used connections
- "Clear history" button (): clears the recently used connections list
- "Copy history" button (): copies history to clipboard
Connection list: contains defined connections
- Connection state indicator
- "Remove connection" button (): closes and drops the connection (button is active when processing is disabled)
- Details can be collapsed and expanded using the triangle button at the right of the connections.

Connections of GTP-C Assembler

Input connection: The input of this module is an ADG type socket received from the INetAssembler module carrying "Storage#2" format messages.
Input connection is defined in INI file. A sample configuration entry:
- inet1=socket-adg://127.0.0.1:4241?listen=1
Output connection: The GTP-C Assembler has three different output connection types:
- Type 1: CDR Writer: A socket type connection carrying information about all transactions and contexts to be written into CDR files. In case more than one CDR writer connections are defined then the CDR related information is distributed among writers equally sending information of the same context towards the same writer.
  
  This type of connection is defined in INI file. A sample configuration entry for a CDR Writer module connection:
  - cdrw=socket-adg://127.0.0.1:4243?anycontent=GTPC.CSOpenStatItem&inverted=true
  In case of multiple CDR Writer module:
  - cdrw-1=socket-adg://127.0.0.1:4243?demux=active&anycontent=GTPC.CSOpenStatItem&inverted=true
- Type 2: PDP/Session creation statistics: A socket type connection carrying information about 'GTPv0 Create PDP Context', 'GTPv1 Create PDP Context' and 'GTPv2 Create Session' transactions to generate success rate statistics from them.
  
  This type of connection is defined in INI file. A sample configuration entry for the statistics module connection:
  - stat=socket-adg://127.0.0.1:42425?anycontent=GTPC.CSOpenStatItem&inverted=false
- Type 3: HAR Writer: A socket type connection carrying information about all transactions to generate HAR event records from them.
  
  This type of connection is defined in INI file. A sample configuration entry for the statistics module connection:
  - har=socket-adg://127.0.0.1:5001
- Important! In case any of defined output connections has a problem then the whole GTP message processing is suspended to avoid data loss.

Connection management

A new input connection can be added when processing state is inactive.
An output connection can be added anytime during the operation.
Connection for CDR Writer and PDP/Session Statistics modules can not be added during the operation but only through the INI file.
A connection
- can be a new one created by pressing the "New connection" button or
- can be added a previously used one from the history list.
Connections can be removed using "Remove connection" button while processing is disabled.

The "Terminal" tab

The "Terminal" provides direct access to the core logic using commands. Available commands are listed on the right. Typically used for debug purposes.

Types of GTP records

Transaction records ('GTP-Tr')

These records contain the assembled GTP transactions from the relevant request and response (and acknowledgement) messages. When a transaction is closed (all messages arrived or the transaction time out expired) the collected messages are written into a transaction record. The record contains the important parameters of the transaction and the context parameters (if there is a context) and the messages belonging to the transaction with their main parameters.

The following transaction and context related parameters are stored in a transaction record:

Start date & time: The date and time of the first message of the transaction
End date & time: The date and time of the last message of the transaction
Total duration: Duration of the transaction (difference between the last and the first message)
IMSI: IMSI value from the messages (when the messages do not contain the IMSI but it can be derived from the context then a question mark ('?') is appended to the stored IMSI)
IMEISV: IMEISV value from the messages (if it is contained in any of the messages)
MSISDN: MSISDN value from the messages (if it is contained in any of the messages)
APN: APN value from the messages (if it is contained in any of the messages)
PDN address(es): User IP address(es) which are assigned to the user equipment
GTP Version: version of the GTP messages
Sequence number: Sequence number value which identifies the messages of a transaction
Transaction opening reason: The reason why the transaction opened
Transaction closing reason: The reason why the transaction closed
Number of stored messages: Number of stored messages in this record

After the general parameters the messages of the transaction are listed with their main parameters and Information Elements (IE).

The following message parameters are stored in a transaction record:

Date & time: The date and time of the message
Link: LinkID of the message
GTP-C Message type: Message type value and interpretation
Source IP address: Source IP address of the message
Target endpoint: Target IP address with the TEID

The following IEs are stored for all messages in a transaction record:

Different TEIDs for user data and control tunnels (v1): eg. Tunnel Endpoint Identifier Data I,Tunnel Endpoint Identifier Control Plane
Different IP Addresses for user data and control tunnels (v1): eg. SGSN Address for user traffic, SGSN Address for signalling
Different FTEIDs for user data and control tunnels(v2): eg. Sender F-TEID for Control Plane, S5/S8-U PGW F-TEID
NSAPI/EPS Bearer ID/Linked Bearer Identity
End User Address/PDN Address Allocation: User IP address(es) which are assigned to the user equipment
Access Point Name (APN)
RAT Type
Serving Network
User Location Information: location information for the user equipment (MCC, MNC,TAC, LAC, RAC, cell information)
Cause: GTP cause in the response message
Teardown Ind (v1): teardown indication flag
Indication Flags (v2)
Bearer context (v2): Bearer context(s) with details (EPS Bearer ID, Bearer QoS Level, Cause, FTEIDs, TFT)

After the message part there are multiple Context/Session Information (CSInfo) if the transaction CDR is bound into Session(s).

CSInfo contains the following parameters:

First Record Timestamp: timestamp of the first record belonging to thisContext/Session. This timestamp equals with the timestamp of the first message.
Previous Record Timestamp: timestamp of the previous record belonging to this Context/Session. This timestamp equals with the timestamp of the first message in the previous record.
APN
Default EBI: EBI of the default bearer belonging to this Context/Session
EBI: EBI of the dedicated bearer belonging to this Context/Session
PGW IP Address: IP Address of the PGW or GGSN
User IP Address: User IP address(es) which are assigned to the user equipment

Context records ('GTP-Ctx')

Contexts are managed based on the assembled GTP transactions. A GTPv1 'Create PDP context' transaction creates new context. The 'Update PDP context' transactions modify the context's parameters and the 'Delete PDP context' transaction (or context time out) closes the context. The same way is applied for GTPv2 sessions based on GTPv2 transactions. Three types of GTP-Context record exist in database: opening, periodic, and closing.

When a context is inactive but alive for a while (INI/[CDR]/CtxCheckPeriodMin) then a context record is put into the database ('GTP-Ctx' record type) containing the parameters of the context. It indicates that the context is ongoing and makes easier to follow and search it for the operator.

A context record contains the following parameters:

IMSI: IMSI value from the messages (when the messages do not contain the IMSI but it can be derived from the context then a question mark ('?') is appended to the stored IMSI)
IMEISV: IMEISV value from the messages (if it is contained in any of the messages)
MSISDN: MSISDN value from the messages (if it is contained in any of the messages)
Context opening reason: The reason why the Context/Session opened
Context closing reason: The reason why the Context/Session closed
Number of transactions: Number of transactions/CDRs belonging to this Context/Session
Number of Control Messages: Number of messages belonging to this Context/Session

After the main parameters the Context/Session CDR contains one CSInfo part which contains the same parameters which were listed above.

Sv transaction summary records ('GTP-Sv')

SRVCC related GTP transactions are bound into transaction summary records. An Sv transaction summary record contains an "SRVCC PS to CS" and an "SRVCC PS to CS complete" or an "SRVCC PS to CS cancel" transaction. (The same is done for "SRVCC CS to PS" transactions.)

An Sv transaction summary record contains the following parameters:

Start date & time: The date and time of the first message of the transaction
End date & time: The date and time of the last message of the transaction
Total duration: Duration of the transaction (difference between the last and the first message)
IMSI: IMSI value from the messages (when the messages do not contain the IMSI but it can be derived from the context then a question mark ('?') is appended to the stored IMSI)
IMEISV: IMEISV value from the messages (if it is contained in any of the messages)
MSISDN: MSISDN value from the messages (if it is contained in any of the messages)
Tr summary type: Type of the transaction (PS to CS, CS to PS)
Tr summary opening reason: The reason why the summary opened
Tr summary closing reason: The reason why the summary closed
Number of transactions: Number of transactions belonging to this Sv summary
Source endpoint: Source IP address with the TEID

After these main paramters comes the list of transactions.

Each transaction contains the following general parameters:

Transaction #N: The number of the GTP transaction
Sequence number: Sequence number value which identifies the messages of a transaction
Transaction opening reason: The reason why the transaction opened
Transaction closing reason: The reason why the transaction closed
Number of stored messages: Number of stored messages in this record

After these general parameters the messages of the transaction are listed with their main parameters and Information Elements (IE).

The following message parameters are stored in a transaction (same as the message parameters in GTP-Tr CDRs):

Date & time: The date and time of the message
Link: LinkID of the message
GTP-C Message type: Message type value and interpretation
Source IP address: Source IP address of the message
Target endpoint: Target IP address with the TEID

The following IEs are stored for all messages in Sv summary record:

Different TEIDs for user data and control tunnels (v1): eg. MME/SGSN Sv TEID for Control Plane
Different IP Addresses for user data and control tunnels (v1): eg. MME/SGSN Sv Address for Control Plane
STN-SR
End User Address/PDN Address Allocation: User IP address(es) which are assigned to the user equipment
Target RNC ID
Source RAI
PTMSI
GUTI
Cause/Cancel Cause: GTP cause in the response message

Configuration (GTPCAssembler.ini) file settings

Section	Entry	Example	Meaning
[Counters]
	ClearOnWrite	false	Clear counters after history file written
	HistoryFile	D:\LogFiles\GTPCAssembler.csv	The path of the counter history file
	HistoryPeriod	15	The counter history file writing period in minutes
[GTPCAssembler]
	SessionContextTimeout	1440	The session or context record timeout in minutes
	SvRecordTimeout	5	The Sv record timeout in seconds
	TEIDRemovingDelayTime	50	The TEID removing delay in milliseconds
	TransactionDelayCloseTime	50	The delay close time of the transactions in milliseconds
	TransactionTimeout	6000	The transaction timeout in milliseconds
	Caption	Assembler_Sv_MSS1	Additional string in application title
	SCRecordPeriod	120	The session or context record timeout in minutes
	FwdRelocationTime	2000	The available time window for forward relocation procedure in milliseconds
	PreferredInterface	s11	Selects the preferred GTP-C interface type; possible values: - s11 - s5s8 - s2b
[Input]
	RestoreChannels	true	Restores the active channels after restart
	SortingQueueDelay	0	The sorting queue delay in milliseconds
	SortingQueueLength	0	The maximum size of the sorting queue
	StoragePointerFilePath	D:\DataFiles-7700	Path for optional storage pointer files (Sga-7700.xxx), if MUFI2 input is used
	SynchronizedIO	false	The input and the output channels will be synchronized
	inet1	socket-adg://127.0.0.1:17000?listen=1	Definition of the listening TCP socket for incoming connection from the INetAssembler module
[Log]
	LogDetailLevel	Normal	Log detail level at startup: 0: Off 1: Normal 2: Detailed 3: Debug
	LogFilesPath	D:\LogFiles	Directory used for storing log files
[Output]
	RestoreChannels	true	Restores the active channels after restart
	SortingQueueDelay	0	The sorting queue delay in milliseconds
	SortingQueueLength	0	The maximum size of the sorting queue
	cdrw	socket-adg://127.0.0.1:4243?anycontent=GTPC.CSOpenStatItem&inverted=true	Definition of the output connection in case only one CDRWriter module is running
	cdrw1	cdrw-1=socket-adg://127.0.0.1:4243?demux=active&anycontent=GTPC.CSOpenStatItem&inverted=true	Definition of the output connection in case multiple CDRWriter modules are running
	stat	socket-adg://127.0.0.1:42425?anycontent=GTPC.CSOpenStatItem&inverted=false	Definition of the output connection towards the GTP Statistics module
	harwriter	socket-adg://127.0.0.1:5001	Definition of the output connection towards the HAR Writer module
[RemoteUI]
	TCPHost	127.0.0.1	Local IP address for the command interface
	TCPPort	16001	Local TCP port for the command interface
[State]
	AutoStart	true	The initial state of the processing
	StateFile	D:\GTPCAssembler.state	The path of the state file

Version history

v4.5.0

(n) GTPCv2/Create Bearer transaction is now handled on S5/S8 interface (redmine 1364).
(n) Src IPAddress and DstIPAddress appears in log lines in some new cases for debug purposes (redmine 1365).
(f) IMSI in CDR ratio for Sv CDR is fixed. (redmine 1376).
(f) Sv active subscribers counter underflow fixed (redmine 1376).
(f) GTP-C invalid message counter error fixed (redmine 1404).

v4.4.2

(f) Fixed IE and message size validation.

v4.4.1

(f) Fixed IE filtering if the size field is invalid.
(f) Fixed APN memory handling.

v4.4.0

(n) The predefined GTP IE content within a GTP record could be extended based on a dynamic IE Type list (csv file).

v4.3.0

(n) Collecting Secondary RAT Usage Data IE (201) into the record content.
(f) Fixed some mistype in counters.

v4.2.0

(f) Fixed message length checking.

v4.1.1

(f) Number of messages belonging to a transaction record is now limited.

v4.1.0

(n) First official release of the re-desinged GTP-C assembling logic.

The GTP-C CDR Assembler module("GTPCAssembler")

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