Methods and apparatuses for establishment of PDU session
Methods and apparatuses for establishment of protocol data unit (PDU) session are disclosed. A first network function determines whether a first session management function (SMF) for a PDU session to be established for a terminal device supports insertion/change of a second SMF. When determining that the first SMF for the PDU session does not support insertion/change of the second SMF, the first network function sends, to a second network function, a query request for discovering at least one second SMF that can serve whole public land mobile network (PLMN) to which the first network function belongs. The first network function receives a query response from the second network function.
1 . A method performed by a first network function, comprising:
receiving a protocol data unit (PDU) session establishment request from a terminal device of a location change;
determining whether a first session management function (SMF), operative with the terminal device, supports deployments topologies with specific SMF service areas (DTSSA) for a PDU session to be established for the terminal device at another SMF;
in response to determining that the first SMF for the PDU session does not support DTSSA, sending, to a second network function, a query request for discovering a second SMF that can serve a whole public land mobile network (PLMN) of the first network function; and
receiving a query response from the second network function to the query request regarding discovery of the second SMF and wherein the query response comprises information about a third SMF that cannot serve the whole PLMN, when the second SMF that can serve the whole PLMN is not available.
2 . The method according to claim 1 , wherein the first SMF is a home SMF (H-SMF) and the second SMF is a visited SMF (V-SMF), wherein the first SMF is an anchor SMF and the second SMF is an intermediate SMF (I-SMF), wherein the first network function is an access and mobility management function (AMF), or any combination thereof.
3 . The method according to claim 1 , wherein the second network function is a network repository function (NRF).
4 . The method according to claim 1 , wherein the query request comprises an indicator indicating to discover only SMFs that can serve the whole PLMN and wherein the indicator is a query parameter of Boolean type with a value “TRUE” indicating to discover one or more SMFs that can serve the whole PLMN.
5 . The method according to claim 1 , wherein the query request comprises an indicator indicating to preferentially discover SMFs that can serve the whole PLMN and wherein the indicator is a query parameter of Boolean type with a value “TRUE” indicating to preferentially discover one or more SMFs that can serve the whole PLMN.
6 . The method according to claim 1 , wherein the query request comprises, as a query parameter for one or more SMFs to be discovered, a predefined tracking area identity (TAI) representing the whole PLMN.
7 . A method performed by a second network function, comprising:
receiving, from a first network function, a query request, wherein the query request is generated by the first network function upon receiving a protocol data unit (PDU) session establishment request from a terminal device of a location change, wherein the first network function determines whether a first session management function (SMF), operative with the terminal device, supports deployments topologies with specific SMF service areas (DTSSA) for a PDU session to be established for the terminal device at another SMF, and wherein in response to determining that the first SMF for the PDU session does not support DTSSA, generates the query request for discovering a second SMF that can serve a whole public land mobile network (PLMN) of the first network function;
discovering the second SMF; and
sending a query response, to the query request, to the first network function regarding discovery of the second SMF and wherein the query response comprises information about a third SMF that cannot serve the whole PLMN, when the second SMF that can serve the whole PLMN is not available.
8 . The method according to claim 7 , wherein the query request indicates to preferentially discover the second SMF; wherein the query response comprises information about the second SMF; or wherein the query request indicates to preferentially discover the second SMF and the query response comprises information about the second SMF.
9 . The method according to claim 7 , wherein the second network function is a network repository function (NRF), wherein the first network function is an access and mobility management function (AMF), or wherein the second network function is the NRF and the first network function is the AMF.
10 . The method according to claim 7 , wherein the query request comprises an indicator indicating to discover only SMFs that can serve the whole PLMN and wherein the indicator is a query parameter of Boolean type with a value “TRUE” indicating to discover one or more SMFs that can serve the whole PLMN.
11 . The method according to claim 7 , wherein the query request comprises an indicator indicating to preferentially discover SMFs that can serve the whole PLMN and wherein the indicator is a query parameter of Boolean type with a value “TRUE” indicating to preferentially discover one or more SMFs that can serve the whole PLMN.
12 . The method according to claim 7 , wherein the query request comprises, as a query parameter for SMFs to be discovered, a predefined tracking area identity (TAI) representing the whole PLMN.
13 . A network node comprising:
at least one processor; and
at least one memory, the at least one memory containing instructions which, when executed by the at least one processor, cause the network node to:
receive a protocol data unit (PDU) session establishment request from a terminal device of a location change;
determine whether a first session management function (SMF), operative with the terminal device, supports deployments topologies with specific SMF service areas (DTSSA) for a PDU session to be established for the terminal device at another SMF;
in response to determining that the first SMF for the PDU session does not support DTSSA, send, to a second network node, a query request for discovering a second SMF that can serve a whole public land mobile network (PLMN) of the network node; and
receive a query response from the second network node to the query request regarding discovery of the second SMF and wherein the query response comprises information about a third SMF that cannot serve the whole PLMN, when the second SMF that can serve the whole PLMN is not available.
14 . A second network node comprising:
at least one processor; and
at least one memory, the at least one memory containing instructions which, when executed by the at least one processor, cause the second network node to:
receive, from a first network node, a query request, wherein the query request is generated by the first network node upon receiving a protocol data unit (PDU) session establishment request from a terminal device of a location change, wherein the first network node determines whether a first session management function (SMF), operative with the terminal device, supports deployments topologies with specific SMF service areas (DTSSA) for a PDU session to be established for the terminal device at another SMF, and wherein in response to a determination that the first SMF for the PDU session does not support DTSSA, generates the query request for discovering a second SMF that can serve a whole public land mobile network (PLMN) of the first network node;
discover the second SMF; and
send a query response, to the query request, to the first network node regarding discovery of the second SMF and wherein the query response comprises information about a third SMF that cannot serve the whole PLMN, when the second SMF that can serve the whole PLMN is not available.