PDP context activation procedure in 2G
For the UE to be able to send and receive data to and from the PDN, the UE should establish a PDP with the GGSN. This is done using the 'PDP context activation' procedure.
Information
Below terms will be used in this procedure,
APN, refers to 'Access Point Name', it is a logical name for the PDN the UE would like to connect to.
PDP address, it is the IP address the GGSN assigned to the PDP context.
QoS, refers to 'Quality of Service', and it describes the priority the nodes shall give to traffic belonging to a certain PDP.
Note
after this process is completed,a PDP context, will be established, on the UE, the SGSN, and the GGSN.
The PDP context, is where, the UE, the SGSN, and the GGSN , stores the information, of this PDP.
PDP context activation procedure in 2G
1. 'Active PDP context request' (UE--> SGSN)
- The UE sends 'Active PDP context request' to the SGSN including the APN it needs to connect to, and the QoS it needs to get.
2. 'Create PDP context' (SGSN <-->GGSN)
Note
The SGSN is already having the subscription data for the UE stored on it from the 'Attach' procedure.
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- The SGSN will validate the APN, and the QoS sent from the UE against the subscription data for this UE.
- If the APN, or the QoS exist in the subscription data is different than the values sent from the UE, the SGSN will use the APN, or QoS exist in the subscription data as the requested values.
- Then, the SGSN will send 'create PDP context request' to the GGSN, including the requested APN, and QoS.
- The GGSN replies to the SGSN with 'Create PDP context response', including the 'IP address', and the QoS the GGSN assigned to this PDP.
5. 'Active PDP context accept' (SGSN --> UE)
- Finally, the SGSN sends 'Active PDP context accept' to the UE, telling the UE that the PDP context activation completed.
- This message will include the IP address the GGSN assigned to this PDP.
Summary
After this procedure is completed,
- 'PDP context' is established on the UE, the SGSN, and the GGSN.
- PDP is established between the UE, and the GGSN.
- The GGSN assigned an IP address, and a QoS to this PDP.
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