Radio Access Bearer/Modify Bearer Request Failure and Error Handling

This section covers the Radio Access Bearers (RAB), Modify Bearer Request and Response (MBR) from PGW and User Plane (UP) failure scenarios.

The following table summarizes cnSGW-C behavior during different stages of call processing for various failure types:

cnSGW-C Behavior for Radio access Bearer and Modify Bearer Response Procedure Failure Scenarios

Message Type

Failure Interface

Failure Response Recevied

Failure Response to be sent

Handling

MBR initial attach

Sx

CONTEXT_NOT_FOUND

EGTP_CAUSE_

NO_RESOURCES_

AVAILABLE

Cleanup PDN with DSR towards PGW and DBR towards MME

Other Failure Response

EGTP_CAUSE_

NO_RESOURCES_

AVAILABLE

Cleanup PDN with DSR towards PGW and DBR towards MME.

Sx_Modification_Req/

Sx_Session_Delete to cleanup resource on UP

Timeout

Timeout on PFCP

EGTP_CAUSE_

NO_RESOURCES_

AVAILABLE

Cleanup PDN with DSR towards PGW and DBR towards MME.

Sx_Modification_Req/

Sx_Session_Delete to cleanup resource on UP

MBR Service Request

Sx

CONTEXT_NOT_FOUND

EGTP_CAUSE_

NO_RESOURCES_

AVAILABLE

Cleanup PDN with DSR towards PGW and DBR towards MME

Other Failure Responses

EGTP_CAUSE_

NO_RESOURCES_

AVAILABLE

Do not update anything in PDN, Ignore S5 Signaling

Timeout

EGTP_CAUSE_

NO_RESOURCES_

AVAILABLE

Do not update anything in PDN, Ignore S5 Signaling

S5

EGTP_CAUSE_

CONTEXT_NOT_

FOUND

EGTP_CAUSE_

CONTEXT_NOT_

FOUND

Sx_Session_Delete send to UP

MBRsp failure to MME (No DBR/DSR)

Other Failure Responses

Failure Response received from PGW

Do not update PDN/DB

Timeout

Timeout from PGW

EGTP_CAUSE_

PEER_NOT_

RESPONDING

Do not update PDN/DB

RAB

Sx

CONTEXT_

NOT_FOUND

(Single PDN call)

EGTP_CAUSE_

REQ_ACCEPTED

Cleanup PDN with DSR towards PGW and DBR towards MME

CONTEXT_

NOT_FOUND

(Multi PDN call and context not found for one PDN)

Send RAB Resp

(EGTP_CAUSE_

REQ_ACCEPTED)

Cleanup the PDN for which context not found received with DSR towards PGW and DBR towards MME

Move other PDN/UE to IDLE

Other Failure Response

EGTP_CAUSE_

REQ_ACCEPTED

Move PDN/UE to IDLE

Timeout

EGTP_CAUSE_

REQ_ACCEPTED

Move PDN/UE to IDLE