Enhanced Event Logging

This chapter describes the MME's Event Logging functionality which occurs at the subscriber level, from the MME to an external server.

Feature Description

The MME handles numerous subscriber calls from different eNodeBs in the network. In order to troubleshoot any issues for a particular subscriber, the events that caused the issue is recorded. The events could be individual procedures listed below:

  • Attach Procedures

  • Detach Procedures

  • TAU Procedures

  • Handover Procedures

  • All types of Service Requests

  • Paging based on different triggers

  • PDN Connectivity Requests

  • All types of PDN detach and network initiated PDN detach procedures

  • Dedicated Bearer Activation Requests

  • Dedicated Bearer Deactivation Requests

  • All types of Bearer modification procedures

  • CSFB procedures

  • SRVCC procedures

  • eCSFB procedures

  • eSRVCC procedures

The Event Data Record is a proprietary feature of StarOS. In this feature, MME provides a debugging framework to capture procedure level information for each subscriber. On the completion of a procedure successfully or unsuccessfully, the MME generates a procedure summary. This summary provides details of the events and issues, which is nearly comparable to real-time debugging.


Important

This feature is license controlled. Please consult your Cisco Account Representative for information about the specific license.

MME supports the following functionality in this feature:

  • Event Logging for 4G subscribers.
  • The Event Records are stored in CSV file format.
  • A framework to collect information and eventually provide log information. The framework is extensible to hold more procedures and information fields.
  • The order of fields are easily changeable.
  • The event logs are generated on completion of the procedure successfully or unsuccessfully. The procedure could be unsuccessful because of local reasons such as – HSS/Peer element triggered reasons, Timeouts for responses, arrival of procedures and so on.
  • Each record has a smgr-no and sequence-no field. If there is no guaranteed delivery of events, the sequence number will help in identifying the lost events.

  • Event reporting can be enabled or disabled through the CLI command reporting-action mme-event-record under the Call Control Configuration mode. For detailed information on feature configuration see the Configuring Event Logging section in this feature chapter.

How Event Logging Works

Event Logging in the MME is implemented by providing subscriber event information to an external server. Data analyzers use the event information in the record, which is stored in the external server, to debug and troubleshoot subscriber issues.

Architecture

This section describes the framework designed in the MME to support Event Logging.

Figure 1. Event Logging - Interfaces


The interface between the MME and the external server is based on SFTP. Each record (CSV record) is generated as comma-separated ASCII values. The MME sends one ASCII formatted CSV record per line. The CSV records are stored in a file. If configured, these files can be compressed before sending it to the external server.

The transfer of CSV record files between the MME and the external server is based on either PULL or PUSH model. In case of the PULL model, the external server is responsible for initiating the SFTP with MME, and in the PUSH model, MME is responsible for sending the CSV record file to external server based on the configured PUSH timer interval.

The event report includes the information in CSV format as shown in the table given below.

Table 1. Information Fields in the EDR

Sl.No

Description

Format information

Range

1

smgr_number

Number

1 up to 1023

2

sequence_no

Number

1 up to 4294967295

3

Time

YYYY-MMM-DD+HH:MM:SS

4

event-idenity

enum: Attach; Detach; TAU; Handover ; Service Request; Paging; PDN Connect/Disconnect; Bearer Activation/Deactivation; CSFB and SRVCC procedures.

5

Result

enum: 0-Success; 1-failure; 2-Aborted;3-eps_only

6

mme-address

Dotted-string

7

Msisdn

String of decimal digits

8

imsi

String of decimal digits

1 - 15 digits

9

Imei (sv)

String of decimal digits

14 or 16 digits

10

old-guti

mcc: mnc: mmegroup: mmecode: mtmsi

11

old-guti-type

Enumeration [0 - native, 1 - mapped]

12

guti

mcc: mnc: mmegroup: mmecode: mtmsi

0 up to 65535

13

Ecgi

mcc: mnc: cellid

14

current-tac

Tac

15

enodeB-id

20 bit value

1 - 1048574

16

disc-reason

Number

0 up to 65535

17

ebi

Number

5-15

18

linked-ebi

Number

19

apn

String

20

pdn-type

Number

1-4

21

ipv4-address

Dotted String

22

ipv6-address

Dotted String

23

pti

Number

1-255

24

qci

Number

1-9,65,66, 69,70,128-254

25

arp

Number

1-255

26

qos-change

Enum [0-No, 1-Yes]

0/1

27

lai

mcc-mnc-lac

If a particular information is not relevant for the procedure being logged or if particular information isn't available, the event record is left blank. For example, if the IMEI is unavailable after the completion of an Attach procedure, the event record is left blank.


Important

All enumerations will be listed by Cisco for every software release. The external server is designed to be aware of the same listing and to interpret the number accordingly. The event records contain 0-based index value of such enumerations to save space and processing overhead.

The Event IDs that are tracked as part of the EDR logging is shown in the below table:

Events

ENUM Value

Attach Procedures

MME_EDR_EVENT_ID_EPS_ATTACH

1

MME_EDR_EVENT_ID_EMERGENCY_ATTACH

2

MME_EDR_EVENT_ID_COMBINED_ATTACH

3

MME_EDR_EVENT_ID_EPS_HO_ATTACH

4

MME_EDR_EVENT_ID_ATTACH_TYPE_MAX

Detach Procedures

MME_EDR_EVENT_ID_UE_INITIATED_DETACH

51

MME_EDR_EVENT_ID_NW_INITIATED_DETACH

52

MME_EDR_EVENT_ID_HSS_INITIATED_DETACH

53

MME_EDR_EVENT_ID_CSFB_UE_INIT_IMSI_DETACH

54

MME_EDR_EVENT_ID_CSFB_NW_INIT_IMSI_DETACH

55

MME_EDR_EVENT_ID_DETACH_TYPE_MAX

TAU Procedures

MME_EDR_EVENT_ID_TAU_SGW_RELOC

101

MME_EDR_EVENT_ID_TAU_NO_SGW_RELOC

102

MME_EDR_EVENT_ID_TAU_COMBINED_SGW_RELOC

103

MME_EDR_EVENT_ID_TAU_COMBINED_NO_SGW_RELOC

104

MME_EDR_EVENT_ID_TAU_PERIODIC

105

MME_EDR_EVENT_ID_TAU_ATTACH_SGW_RELOC

106

MME_EDR_EVENT_ID_TAU_ATTACH_NO_SGW_RELOC

107

MME_EDR_EVENT_ID_TAU_ATTACH_COMBINED_SGW_RELOC

108

MME_EDR_EVENT_ID_TAU_ATTACH_COMBINED_NO_SGW_RELOC

109

MME_EDR_EVENT_ID_TAU_TYPE_MAX

Handover Procedures

MME_EDR_EVENT_ID_S1_HO_SGW_RELOC

151

MME_EDR_EVENT_ID_S1_HO_NO_SGW_RELOC

152

MME_EDR_EVENT_ID_X2_HO_SGW_RELOC

153

MME_EDR_EVENT_ID_X2_HO_NO_SGW_RELOC

154

MME_EDR_EVENT_ID_INBOUND_S10_HO_SGW_RELOC

155

MME_EDR_EVENT_ID_INBOUND_S10_HO_NO_SGW_RELOC

156

MME_EDR_EVENT_ID_INBOUND_S3_HO_SGW_RELOC

157

MME_EDR_EVENT_ID_INBOUND_S3_HO_NO_SGW_RELOC

158

MME_EDR_EVENT_ID_INBOUND_GNGP_HO

159

MME_EDR_EVENT_ID_OUTBOUND_S10_HO

160

MME_EDR_EVENT_ID_OUTBOUND_S3_HO

161

MME_EDR_EVENT_ID_OUTBOUND_GNGP_HO

162

MME_EDR_EVENT_ID_HO_TYPE_MAX

Service Request Procedures

MME_EDR_EVENT_ID_SERV_REQ_UE_INITIATED

201

MME_EDR_EVENT_ID_SERV_REQ_NW_INIT_PROC

202

MME_EDR_EVENT_ID_SERV_REQ_EXTENDED

203

MME_EDR_EVENT_ID_SERV_REQ_TYPE_MAX

Paging Procedures

MME_EDR_EVENT_ID_PAGING_DDN_TRIGGER

251

MME_EDR_EVENT_ID_PAGING_DETACH_TRIGGER

252

MME_EDR_EVENT_ID_PAGING_BRR_TRIGGER

253

MME_EDR_EVENT_ID_PAGING_IDR_QUERY_TRIGGER

254

MME_EDR_EVENT_ID_PAGING_PCSCF_RESTORATION

255

MME_EDR_EVENT_ID_PAGING_UE_OFFLOAD_TRIGGER

256

MME_EDR_EVENT_ID_PAGING_SGS_TRIGGER

257

MME_EDR_EVENT_ID_PAGING_GMLC_TRIGGER

258

MME_EDR_EVENT_ID_PAGING_PGW_NODE_RESTORATION

259

MME_EDR_EVENT_ID_PAGING_S102_TRIGGER

260

MME_EDR_EVENT_ID_PAGING_IPNE_QUERY_TRIGGER

261

MME_EDR_EVENT_ID_PAGING_TYPE_MAX

PDN Connectivity Requests

MME_EDR_EVENT_ID_PDN_CONN_REQ

301

MME_EDR_EVENT_ID_PDN_EMERGENCY_CONN_REQ

302

MME_EDR_EVENT_ID_PDN_CONN_TYPE_MAX

UE and Network Initiated PDN Detach

MME_EDR_EVENT_ID_UE_PDN_DISCONN_REQ

351

MME_EDR_EVENT_ID_MME_PDN_DISCONN_REQ

352

MME_EDR_EVENT_ID_HSS_PDN_DISCONN_REQ

353

MME_EDR_EVENT_ID_NW_PDN_DISCONN_REQ

354

MME_EDR_EVENT_ID_PDN_DISCONN_TYPE_MAX

Dedicated Bearer Activation Requests

MME_EDR_EVENT_ID_DED_BEARER_ACT_REQ

401

MME_EDR_EVENT_ID_DED_BEARER_ACT_MAX

Dedicated Bearer Deactivation Requests

MME_EDR_EVENT_ID_UE_DED_BEARER_DEACT_REQ

451

MME_EDR_EVENT_ID_MME_DED_BEARER_DEACT_REQ

452

MME_EDR_EVENT_ID_PGW_DED_BEARER_DEACT_REQ

453

MME_EDR_EVENT_ID_DED_BEARER_DEACT_MAX

Bearer Modification Requests

MME_EDR_EVENT_ID_NW_BEARER_MODIF

501

MME_EDR_EVENT_ID_HSS_BEARER_MODIF

502

MME_EDR_EVENT_ID_BEARER_MODIF_TYPE_MAX

CSFB Prodecures

MME_EDR_EVENT_ID_CSFB_MO_CALL

551

MME_EDR_EVENT_ID_CSFB_MT_CALL

552

MME_EDR_EVENT_ID_CSFB_MO_PRIORITY_CALL

553

MME_EDR_EVENT_ID_CSFB_MT_PRIORITY_CALL

554

MME_EDR_EVENT_ID_CSFB_MO_EMERGENCY_CALL

555

MME_EDR_EVENT_ID_CSFB_MO_SMS

556

MME_EDR_EVENT_ID_CSFB_MT_SMS

557

MME_EDR_EVENT_ID_ECSFB_MO_CALL

561

MME_EDR_EVENT_ID_ECSFB_MT_CALL

562

MME_EDR_EVENT_ID_ECSFB_EMERGENCY

563

SRVCC Procedures

MME_EDR_EVENT_ID_SRVCC_SV_CSPS

601

MME_EDR_EVENT_ID_SRVCC_SV_CS

602

MME_EDR_EVENT_ID_SRVCC_SV_NO_DTM

603

MME_EDR_EVENT_ID_SRVCC_1XRTT

604

MME_EDR_EVENT_ID_SRVCC_MAX

The status of each event is as shown in the table given below:

Table 2. Event Status
Sl No. Format Information ENUM Value
1 MME_EDR_EVENT_RESULT_SUCCESS 0
2 MME_EDR_EVENT_RESULT_FAILURE 1
3 MME_EDR_EVENT_RESULT_ABORT 2
4 MME_EDR_EVENT_RESULT_EPS_ONLY 3

Limitations

The reliability of event generation is limited by the CDRMOD framework – particularly in the following ways:

  • Any reboot of the chassis, will result in loss of records that are not yet flushed to the hard-disk or an external server
  • In case of overload of the CDRMOD, the SESSMGR ignores event records if the queue is full.

  • EDR sequence numbers are within the scope of the Session Manager. If a different Session Manager is selected, the EDR sequence number may reset or continue from the last sequence number allocated in that Session Manager.

  • The statistics are key parameters for logging EDRs, if the statistics have any discrepancies the EDRs are not generated. Listed below are some scenarios where the EDRs are not generated due to discrepancies in statistics:

    • Network or MME initiated dedicated bearer de-activation during SRVCC procedures.

    • HSS initiated modification failures.

    • HSS initiated PDN disconnect failures.

Relationship with Other Products

The SGSN has a similar function, GMM-SM Event Logging. For information about this functionality refer to the SGSN Administration Guide.

Configuring Event Logging

The following configurations are discussed in this section for Event Data Records (EDRs):

Enabling Event Logging

The following CLI configuration is executed in the Call Control Profile mode to enable Event Logging on the MME. 

config 
 call-control-profile profile_name  
 reporting-action mme-event-record  
            exit

Notes:

  • The call-control-profile configuration enables Event Logging for MME, provided this profile is associated to the mme-service through operator policy and subscriber map.
  • reporting-action enables procedure reports.
  • mme-event-record reports MME procedures in the form of event records using CDRMOD.

Enabling EDR Logs

The CDRMOD proclet writes the individual records into a single file received from several session managers. The CDRMOD proclet is enabled with the configuration below. 

config 
 context context_name  
 edr-module active-charging-service reporting 
                  cdr { push-interval interval_time | remove-file-transfer | use-harddisk | transfer-mode { pull | push primary { encrypted-url | url } url [ secondary { encrypted-secondary | secondary-url } url_ ]  } [ module-only ] }   
                   end

Configuring File Parameters

File parameters can be configured using the configuration given below. 

config 
 context context_name  
 session-event-module  
                  file name file_name current-prefix current_file_prefix rotation volume file_rotation_size rotation time file_rotation_time  field-separator underscore sequence-number padded charging-service-name include compression gzip }  
                  end

EDR Profile Association

The Call Control Profile configuration enables event Logging for MME, provided the EDR profile is associated to the MME-Service through Operator Policy and Subscriber Map (LTE-Policy). 

config 
 operator-policy name  policy_name  
 associate call-control-profile edr_profile_name 
            exit 
 lte-policy  
 subscriber-map map_name  
 precedence precedence_value match-criteria all operator-policy-name policy_name  
                  exit 
            exit 
 context context_name  
 mme-service service_name  
 associate subscriber-map map_name  
                  end

Verifying the Event Logging Configuration

The following commands are used to verify the parameters for Event Logging.

  • show call-control-profile full all
  • show operator-policy full all
  • show lte-policy subscriber-map name sub1
  • show mme-service all

Monitoring and Troubleshooting Event Logging

This section provides information on how to monitor Event Logging.

Event Logging Show Command(s) and/or Outputs

This section provides information regarding show commands and/or their outputs in support of Event Logging.

The show commands in this section are available in support of the Event Logging.

show call-control-profile full all 

Call Control Profile Name = TEST 
SAMOG Home PLMN                                            : Not configured 
Accounting Mode (SGW/SaMOG)                    : None 
Accounting stop-trigger (SGW)                : Not configured 
Accounting Policy (SaMOG)                        : Not configured 
Event Data Records (MME)                          : Enabled

show cdr statistics

On running the above command , the following statistics are displayed: 

EDR-UDR file Statistics: 
CDRMOD Instance Id: 2 
    Overall Statistics: 
      Files rotated:                                                                                30 
      Files rotated due to volume limit:                                          0 
      Files rotated due to time limit:                                              3 
      Files rotated due to tariff-time:                                            0 
      Files rotated due to records limit:                                    11 
      File rotation failures:                                                                0 
      Files deleted:                                                                                  7 
      Records deleted:                                                                              0 
      Records received:                                                                    23754 
      Current open files:                                                                        0 
 
Time of last file deletion:                              Sunday November 08 23:32:53 EST 2015 
Session-Event Record Specific Statistics: 
Session-Event files rotated:                                                        30 
Session-Event files rotated due to volume limit:                  0 
Session-Event files rotated due to time limit:                      3 
Session-Event files rotated due to tariff-time:                    0 
Session-Event files rotated due to records limit:              11 
    Session-Event file rotation failures:                                    0 
    Session-Event files deleted:                                                      7 
    Session-Event records deleted:                                                  0 
    Session-Event records received:                                        23754 
    Current open Session-Event files:                                            0 
Time of last Event file deletion:                Sunday November 08 23:32:53 EST 2015