Coordinated change of protocol data unit session anchors

A method for coordinated change of Protocol Data Unit, PDU, Session Anchors, PSAs, the method comprising:

• at a Session Management Function, SMF, node:
• determining that a PSA change is needed for a first PDU session having a first PSA, where the first PDU session and a second PDU session are redundant PDU sessions with each other;
• sending, to a node for maintaining PSA change status for PDU sessions, a request for the PSA change for the first PDU session;
• receiving, from the node for maintaining PSA change status for PDU sessions, a response to the request for the PSA change for the first PDU session, and:
• if the response to the request for the PSA change for the first PDU session indicates that the PSA change is allowed, initiating the PSA change for the first PDU session;
• and
• if the response to the request for the PSA change for the first PDU session indicates that the PSA change is temporarily prohibited, not initiating the PSA change for the first PDU session.

A method for coordinated change of Protocol Data Unit, PDU, Session Anchors, PSAs, the method comprising:

• at a node for maintaining PSA change and handover status for PDU sessions:
• receiving a request for a handover for a first PDU session having a first PSA, where the first PDU session and a second PDU session are redundant PDU sessions with each other;
• determining whether the handover for the first PDU session is temporarily prohibited;
• upon determining that the handover for the first PDU session is temporarily prohibited, denying the request for the handover for the first PDU session;
• and
• upon determining that the handover for the first PDU session is not temporarily prohibited:
• allowing the handover for the first PDU session;
• setting a change status associated with the first PDU session to indicate that a PSA change or handover for the first PDU session is temporarily prohibited;
• subsequently receiving an indication that the handover for the first PDU session is completed;
• and
• setting the change status associated with the first PDU session to indicate that a PSA change or handover for the first PDU session is allowed,
• wherein determining that the handover for the first PDU session is temporarily prohibited comprises at least one of:
• determining that the first PDU session is currently undergoing a PSA change;
• determining that the second PDU session is currently undergoing a handover;
• and determining that the second PDU session is currently undergoing a PSA change.

A method for coordinated change of Protocol Data Unit Session Anchors, PSAs, the method comprising:

• at a first node being associated with a first PDU session:
• determining that a handover is needed for the first PDU session having a first PSA, where the first PDU session and a second PDU session are redundant PDU sessions with each other;
• determining whether the handover for the first PDU session is temporarily prohibited;
• upon a determination that the handover for the first PDU session is temporarily prohibited, postponing the handover for the first PDU sesssion;
• and
• upon a determination that the handover for the first PDU session is not temporarily prohibited:
• setting the change status associated with the first PDU session to indicate that a PSA change or handover for the first PDU session is temporarily prohibited;
• performing the handover for the second PDU session;
• and
• setting the change status associated with the first PDU session to indicate that a PSA change or handover is allowed,
• wherein determining that a PSA change or handover for the first PDU session is temporarily prohibited comprises at least one of:
• determining that the first PDU session is currently undergoing a PSA change;
• determining that the second PDU session is currently undergoing a PSA change;
• and determining that the second PDU session is currently undergoing a handover.