The following call flow illustrates, at a high-level, the IDFT support without S-GW Relocation.

The following call flow illustrates the IDFT support with S-GW Relocation.

The above call flow describes the IDFT tunnels establishment and deletion with S-GW relocation and without MME change.

If IDFT tunnels are not deleted by MME, then S-GW initiates the local delete of IDFT tunnels.

This feature supports the following scenarios for the Pure-S and Collapse calls:

• S-GW relocation with same MME

• S-GW relocation with same MME and different eNodeB

• S-GW relocation with different MME

• S1-based eNodeB Handoff

• EUTRAN to UTRAN Handoff

  Note	S4 interface is not supported in CUPS. Hence any EUTRAN to UTRAN handoffs (and vice-versa) involving S4 interface is also not supported.

• EUTRAN to UTRAN Handoff with S-GW relocation

• UTRAN to EUTRAN Handoff

• UTRAN to EUTRAN Handoff with S-GW relocation

• Sx transaction timeout during IDFT setup or removal

• Pending Sx transaction (event from PCRF or OCS) and IDFT request comes in

• Create Bearer Request (CBR) during Active IDFT

• Update Bearer Request (UBR) during Active IDFT

• Delete Bearer Request (DBR) during Active IDFT

• Modify Bearer Request (MBR) behavior on other PDN during Active IDFT

• Source MME path failure

• Target MME path failure

• MME path failure with NTSR enabled

• eGTP-C S5 path failure

• eGTP-C S5 path failure with P-GW restart notification enabled

• Sx path failure (clean IDFT and calls)

• Abort session (clear sub all, local abort, and so on.)

• CBR, UBR on other PDN during Active IDFT

• DBR on other PDN/bearer during Active IDFT

• S1-u path failure for target eNodeB

• S-GW path failure for target S-GW

• S1-u error indication on the default bearer while Active IDFT

• S1-u error indication on the dedicated bearer while Active IDFT

• S1-u error indication from the target S-GW to source S-GW bearer

• S1-u error indication from the target eNodeB to target S-GW bearer

The IDFT feature supports the following functionality:

• Create IDFT request for Collapsed, Pure-S, combination of Collapsed and Pure-S multi-PDN calls with multiple bearers.

• Data transfer on downlink and uplink IDFT bearers.

• Deletion of IDFT request from MME. Also, timer-based deletion of IDFT bearer after expiration of a default value of 100 seconds, if the MME does not send an IDFT request for deletion.

• Deletion of IDFT PDN, including Clear/Delete subscribers from MME/P-GW, when normal PDN goes down.

• Sx-Path failure handling in case of Pure-S and collapsed calls during IDFT Active/ IDFT Create Sx-Pending state.

• Message interaction and collision during IDFT PDN establishment or deletion with any other procedure.

• S11/S5 and Sx Path Failure Handling on non-IDFT PDN is now supported when IDFT PDN is Active.

Important

Transport GTP-U address capability is assumed to be same across eNodeB and S-GW.

On Control Plane, use the following CLI commands to enable or disable the IDFT feature.

configure 
   context context_name 
      sgw-service service_name 
         [ default | no ] egtp idft-support 
         end 

NOTES:

• idft-support : Enables/Disables the IDFT feature in CUPS.

• By default, the IDFT feature is disabled and this CLI command is applicable on run-time change.

This section provides information regarding show commands and their outputs in support of the feature.