Subscriber Tracing from SMF

MON SUB IE for Subscriber Tracing from SMF

SMF sends a proprietary MON SUB IE to the UPF to start or stop a subscriber tracing session for a given IMSI. The MON SUB IE is a private Information Element (IE), which can be included only when the tracing options selected require U-Plane participation.

PFCP_IE_MONITOR_SUBSCRIBER_INFO

Subscriber Tracing

Action: STOP / START monitor subscriber tracing. STOP =1, START =2.

Note

D = DATA events tracing is ON when D=1. The 8 octets (d to d+7) contain data events tracing (fastpath) information should be present only when, D=1.

C = CONTROL events tracing is ON when C=1.

Data Tracing (fastpath) Information (8 octets): It contains the data filter parameters like Packet capture, Packet capture size, and MEH header.

  • Octet 1:

    • Bit 1: VPP enable/disable

    • Bit 2: FCAP - Packet capture

    • Bit 3: MEH present

    • Bit 4 to 6: Priority

  • Octet 2 to 3: Packet size

  • Octet 4 – 8: Reserved for future use. Currently, all set to 0.

Protocol Tracing Information (16 octets/128 bits): The 16 octets, p-to-(p+15), contain protocol tracing information. It is present only when either the control flag (C) or the data flag (D) is enabled. Each bit represents a unique protocol to monitor. For example, if the 49th bit is 1, PFCP events tracing is ON. The control event flag controls the Protocol Tracing Rulematch Events (Option 34), L3 Data (Option 19), GTPU (Option 26), EDR (Option 77), and Subscriber Summary After Call Disconnect.

Enabling Subscriber Tracing from SMF

The SMF sends the MON SUB IE in either of two situations:

  1. Session Establishment Request (for a new session), or

  2. Session Modification Request (for ongoing session)

Enabling subscriber tracing on SMF is done through a new CLI. For more details, see SMF Monitor Subscriber Configuration.

Note

Enabling of session tracing is not piggybacked on any PFCP message. Session Tracing is enabled on UPF via a separate Sx Modification Request from SMF.

Disabling Subscriber Tracing from SMF

To disable the subscriber tracing from SMF, the MON SUB IE with Action = STOP, is sent in a Session Modification Request.

PCAP Generation

UPF generates the slowpath and fastpath PCAPs in the following 3 situations:

  1. When subscriber tracing is stopped from SMF via the N4 interface.

  2. When a subscriber session is deleted gracefully.

  3. When a subscriber session is locally purged on UPF.

Subscriber Trace Status Report IE (Private IE)

The Subscriber Trace Status Report IE is sent corresponding to all monsub START request received from SMF.

Subscriber Trace Status Report

The status code indicates the acceptance or the rejection of the subscriber trace at UP. Status code = 0 means, a success. Values 1-255 uniquely specifies a specific error code or a notification. The list of error codes and notifications are defined post development.

Error Code and Notification Table
Status Code Status Description
MONSUB_SM_SUCCESS (0)
MONSUB_SM_ERROR_FAILURE (1) MonSub: Generic Failure status received
MONSUB_SM_ERROR_UNSUPPORTED (2) MonSub: Unsupported Failure!
MONSUB_SM_ERROR_SESSION_EXIST_NONE (3) MonSub: Session not Found!" );
MONSUB_SM_ERROR_SESSION_LIMIT_EXCEED (4) MonSub: Max Connections reached!
MONSUB_SM_ERROR_SESSION_INVALID_PARAM (5) MonSub: Connect Message Failed!
MONSUB_SM_ERROR_SESSION_ALLOC_FAIL (6) MonSub: Could not allocate monsub session at NPU!
MONSUB_SM_ERROR_CONFIG_INVALID_PARAM (7) MonSub: Config Message Failed!
MONSUB_SM_ERROR_MONITOR_LIMIT_EXCEED (8) MonSub: Max Stream Limit reached!
MONSUB_SM_ERROR_MONITOR_INVALID_PARAM (9) MonSub: Monitor Message Failed!
MONSUB_SM_ERROR_MAX (10) MonSub: Max Error!
MONSUB_COPROCDATA_CORRUPTED (11) MonSub: File Handling Process Failed!
MONSUB_MAX_TRACING_SESSIONS_REACHED (12) MonSub: Maximum Number of Tracing Sessions reached!
MONSUB_STOP_RECVD_WAIT_POLL_TIMEOUT (13) MonSub: STOP notification is Successful. Wait till the poll-timeout configuration to start the next tracing!
MONSUB_FILECOPY_SOURCE_DIR_NOT_EXIST (14) MonSub: Source Directory does not exist!
MONSUB_FILECOPY_DEST_DIR_NOT_EXIST (15) MonSub: Destination Directory does not exist!
MONSUB_FILECOPY_SOURCE_DIR_OPEN_FAILURE (16) MonSub: Unable to open Source Directory!
MONSUB_FILECOPY_DEST_DIR_OPEN_FAILURE (17) MonSub: Unable to open Destination Directory!
MONSUB_FILECOPY_SOURCE_OPEN_FAILED (18) MonSub: Unable to open Source File!
MONSUB_FILECOPY_DESTINATION_OPEN_FAILED (19) MonSub: Unable to open Destination File!
MONSUB_FILECOPY_DONE_FILE_DELETION_FAILED (20) MonSub: Unable to delete .done file in Source Path!
MONSUB_FILECOPY_PCAP_FILE_DELETION_FAILED (21) MonSub: Unable to delete .pcap file in Destination Path!
MONSUB_RESPONSE_NPUMGR_MONSUB_SESS_FAILED (23) MonSub: Messenger Failure during Session Notification to NPUMGR!
MONSUB_RESPONSE_NPUMGR_MONSUB_CFG_FAILED (24) MonSub-Config push to NPUMGR!
MONSUB_RESPONSE_NPUMGR_MONSUB_MONITOR_FAILED (25) MonSub-Monitor Notification to NPUMGR!
MONSUB_RESPONSE_COPROC_FAILED (27) MonSub: File Handling Process Failed!
MONSUB_RESPONSE_FILE_TRANSFER_SUCCESS (28) MonSub: File Transfer successful.
MONSUB_RESPONSE_FILE_TRANSFER_FAILED (29) MonSub: File Transfer failed!
MONSUB_ADMINISTRATIVE_DISCONNECT (30) MonSub: Administrative Disconnect!
MONSUB_FILECOPY_DESTINATION_DISK_FULL (31) MonSub: No space left in Destination Path!
MONSUB_FILECOPY_COPROC_ABRUPTLY_KILLED (32) MonSub: File copy co-proc terminated abruptly!
MONSUB_LOGGING_COPROC_ABRUPTLY_KILLED (33) MonSub: Logging co-proc terminated abruptly!
MONSUB_SM_DISCONNECT (34)
MONSUB_FILECOPY_STATUS_MAX (35)
Other Internal Error adding protocol monitor trace - aborting…