Following messages are supported by MEF interface:

• Subscriber-Activate-Request

• Subscriber-Modify-Request

• Subscriber-Delete-Request

• Subscriber-Audit-Request

• Subscriber-Audit-Response

Subscriber-Activate-Request

MME sends a Subscriber-Activate-Request message to MEF server whenever the MEC PDN gets created for the UE either through Attach or PDN-Connect procedure. After Modify-Bearer-Request sent to SGW, MME sends this message to MEF with the following details:

Subscriber-Modify-Request

MME sends Subscriber-Activate-Request message to the MEF server, whenever UE mobility occurs through Tracking-Area-Update (TAU), Service-Request, Handovers (S1/X2 Handover), and Location-Report with the ECGI change. MME does not send this event to MEF if any of the earlier procedures resulted only in the TAI change and no change in ECGI. Once the earlier mobility procedure compiled successfully with the ECGI change the MME sends the following details to MEF.

Subscriber-Delete-Request

MME sends Subscriber-Delete-Request message to MEF server, whenever MEC PDN gets terminated for the UE either through Detach or PDN-Disconnect procedure. MME sends this message to MEF with the following details.

MEF performs auditing for each UE periodically or when MEF receives MEC messages for unknown IMSI.

Subscriber-Audit-Request

MEF performs auditing for each UE periodically and when it receives MEC messages for unknown IMSI. It sends the Subscriber-Audit-Request message to MME with the IMSI of the subscriber for which it wants to perform an audit. In case of auditing for Unknown-IMSI, MEF sends the TEID as 0 in GTPv2 header, otherwise MEF fills the TEID information that is received in the Subscriber-Activate-Request from MME. MME responds with Subscriber-Audit-Response to MEF.

Subscriber-Audit-Response

MME sends this message to MEF when it receives the Subscriber-Audit-Request for an IMSI. It responds with success or failure cause based on the availability of UE information. If MME does not have valid UE-Context for the IMSI received in Audit-Request, it responds with cause as “Context-Not-Found”, otherwise it sends the IMSI, PAA (IP address IPv4/v6), ECGI, TAI, APN-NI, UE-Usage-Type and so on.

REQ-ACCEPTED (Successful scenario where the MME can find the UE) and CONTEXT-NOT-FOUND (Failure cases where the MME is unable to find UE or invalid IMSI, and so on) are valid causes that are included in the Subscriber-Audit-Response's for different conditions.

Connection Auditing

MME/MEF performs the connection auditing by sending "ECHO-REQ" after the echo timer expiry which is configurable at MME under egtp-service.

ECHO Request: MME/MEF sends the ECHO-REQ whenever the configured echo-timer expires. MME initiates the ECHO-REQ when it has one valid session at-least towards the peer MEF server.

ECHO Response

MME/MEF responds with ECHO-RESPONSE whenever it receives ECHO-REQ from the peers.

• New MEF messages use the unused Message Type from GTPv2 specification. Any new message type defined by 3GPP for GTPv2 will impact the working of MEF interface.

• When MME requests PDN disconnection at GW-U area change, "Subscriber-Delete-Request" is sent and then re-selection of MEF is done at PDN connection establishment.

• MEF grouping and MEF redundancy (primary/secondary link) are not supported in this release.

• Run-time configuration change of MEF server address and disabling of MEF interworking will take effect only for the new subscribers.

• Run-time configuration change to remove association of MEF service under MME service and removal of MEF service will take effect immediately.

Use the following configuration to associate the given egtp-service for MEF interface at the MME.

configure 
   context context_name 
      mme-service service_name 
         associate egtp-mef-service  egtp_mef_service_name context context_name 
         no associate egtp-mef-service 
         end 

NOTES:

• no Removes the association for MEF interface at the MME.

• egtp-mef-service egtp_mef_service_name : Associates the given egtp-service for MEF interface at the MME.

  egtp_mef_service_name must be a string from 1 to 63.

• context context_name : Specifies the context to which the service belongs.

  context_name must be a string from 1 to 79.

Use the following configuration to configure peer MEF Address.

configure 
   lte-policy  
      tai-mgmt-db db_name 
         tai-mgmt-obj obj_name 
             [ no ] up-address ip_address mef-address ip_address 
             end 

NOTES:

• no : Disables the configuration of peer MEF address.

• mef-addressip_address : Configures the peer MEF server address for MEF signalling. ip_address must be any IPV4 address of notation ##.##.##.## or IPV6 address of notation ####:####:####:####:####:####:####:#### . IPV6 also supports :: notation.

show mme-service all

The output of this command includes the following fields:

• EGTP MEF Context

• EGTP MEF Service

show mme-service name <service-name>

The output of this command includes the following fields:

• EGTP MEF Context

• EGTP MEF Service

Show lte-policy tai-mgmt-db name <db-name>

• MEF-ADDRESS

Show lte-policy tai-mgmt-db name <db-name> tai-mgmt-obj name <obj-name>

• MEF-ADDRESS

Show egtpc statistics

The output of this command includes the following fields:

MEF Messages:

• MEF Subscriber Activate Request:

  • Initial TX:

• MEF Subscriber Modify Request:

  • Initial TX:

• MEF Subscriber Delete Request:

  • Initial TX:

• MEF Subscriber Audit Response:

  • Initial TX:

• MEF Subscriber Audit Request:

  • Initial RX:

Important

MEF statistics block is displayed only when the values are non-zero.

Show egtpc statistics event-statistics

The output of this command includes the following fields:

Event Statistics at EGTPC:

• MEF Subscriber Audit Indication Evt

Request Events (from SAP to EGTPC):

• MEF Subscriber Activate Request Evt

• MEF Subscriber Modify Request Evt

• MEF Subscriber Delete Request Evt

Response Events (from SAP to EGTPC)

• MEF Subscriber Audit Response Evt

Show mme-service statistics debug

The output of this command includes the following fields:

Recovery:

• Failed MEF EGTPC Recovery

• Bad Peer MEF ctxt

• Failed MEF tunnel handles

Checkpoint:

• Bad MEF Ctxt