Tear Down indication in Gtpv1 (Teardown Ind)

Tear Down indication in Gtpv1 (Teardown Ind)

As you have seen a parameter named teardown Ind in Delete PDPContext GTP message from SGSN to GGSN. This parameter has a great significance in Deleting already existed PDP Contexts.

Teardown Indication IE has only two possible values 0 and 1.

For deleting existing PDP Context , there are 4 different scenarios where tear down indicator IE plays its role :

1.       If 1, then all the PDP Context that share same PDP address ( UE is allocated an IP/PDP address, say 70.70.70.1 for primary PDP context  and secondary PDP context linked with this primary PDP context has same IP/PDP address) is deleted.

Example:  If secondary PDP context is deleted with tear down set to 1 then with secondary PDP context as well as primary PDP context  gets deleted and vice versa.

2.       If 0, then only PDP context identified by NSAPI (bearer-ID) in Delete PDP Context gets deleted not all PDP context linked with the same UE/PDP address.

Note: If primary context is deleted with tear down indication to zero then primary PDP context  gets deleted and secondary context linked if any, with this primary PDP context  gets the primary PDP context role.

3.       If not mentioned any value for tear down indication then PDP context identified by NSAPI (bearer-ID) in Delete PDP Context gets deleted not all PDP context linked with the same UE/PDP address.

4.       If 0 or no value, and only primary PDP Context is activated/available, then GGSN ignore the Delete PDP Context message and discard.