Cisco Cisco ASR 5000
Network Requested Secondary PDP Context Activation
▀ How It Works
▄ SGSN Administration Guide, StarOS Release 18
Figure 64. Call Flow: Successful Network Requested Secondary Activation (Gn.Gp)
GGSN initiates secondary PDP activation by sending an Initiate PDP Context Activation Request (linked NSAPI,
requested Qos, TFT, PCO, correlation-Id) to SGSN. The SGSN sends a Requested Secondary PDP Context Activation
(linked Ti, Ti, Qos Requested, TFT, PCO) message to MS. The QoS Requested, TFT and PCO are transparently passed
through the SGSN.
requested Qos, TFT, PCO, correlation-Id) to SGSN. The SGSN sends a Requested Secondary PDP Context Activation
(linked Ti, Ti, Qos Requested, TFT, PCO) message to MS. The QoS Requested, TFT and PCO are transparently passed
through the SGSN.
The TFT sent by the GGSN contains the uplink packet filters to be applied at the MS. The GGSN uses the Correlation-
Id is to correlate the subsequent Secondary PDP Context Activation procedure with the Initiate PDP Context Activation
Request. The SGSN includes this correlation-Id in the subsequent Create PDP Context Request to GGSN.
Id is to correlate the subsequent Secondary PDP Context Activation procedure with the Initiate PDP Context Activation
Request. The SGSN includes this correlation-Id in the subsequent Create PDP Context Request to GGSN.
The MS sends an Activate Secondary PDP Context Request (linked Ti, Ti, NSAPI, PCO, QoS Requested). Linked Ti,
Ti, Qos Requested will be the same as received in a previous message from SGSN. The TFT sent by the MS will
contain the downlink packet filters to be applied at GGSN.
Ti, Qos Requested will be the same as received in a previous message from SGSN. The TFT sent by the MS will
contain the downlink packet filters to be applied at GGSN.
On receiving a successful response (Activate Secondary PDP Context Request), the SGSN sends an Initiate PDP
Context Activation Response with cause as Accepted to the GGSN. Additionally the SGSN sends a Create PDP Context
Request (correlation-Id, linked NSAPI, NSAPI, TFT, PCO) to the GGSN. After the GGSN responds with a Create PDP
Response with cause Accepted, the SGSN completes the procedure by sending an Activate Secondary PDP Context
Accept to the MS.
Context Activation Response with cause as Accepted to the GGSN. Additionally the SGSN sends a Create PDP Context
Request (correlation-Id, linked NSAPI, NSAPI, TFT, PCO) to the GGSN. After the GGSN responds with a Create PDP
Response with cause Accepted, the SGSN completes the procedure by sending an Activate Secondary PDP Context
Accept to the MS.
Unsuccessful Activation for Gn/Gp SGSN
After sending a Requested Secondary PDP Context Activation to the MS, the SGSN starts the T3385 radio interface
retransmission timer. Upon expiry the SGSN resends the message a maximum of four retries. Upon the fifth expiry, the
SGSN releases all allocated resources and sends an Initiate PDP Context Activation Response to the GGSN with cause
as “MS is not GPRS responding”.
retransmission timer. Upon expiry the SGSN resends the message a maximum of four retries. Upon the fifth expiry, the
SGSN releases all allocated resources and sends an Initiate PDP Context Activation Response to the GGSN with cause
as “MS is not GPRS responding”.
The MS may choose to reject the Secondary Activation by the network. In such cases, the MS sends a Requested
Secondary PDP Context Activation Reject message with appropriate cause. The SGSN informs the GGSN by sending it
an Initiate PDP Context Activation Response with an appropriate GTP cause mapped from SM (Session Management)
cause. SM-to-GTP cause mapping is listed in the table below.
Secondary PDP Context Activation Reject message with appropriate cause. The SGSN informs the GGSN by sending it
an Initiate PDP Context Activation Response with an appropriate GTP cause mapped from SM (Session Management)
cause. SM-to-GTP cause mapping is listed in the table below.