Managing Service Function Chains

A method in a policy control function (PCF) of moving a session from a service function chain (SFC) to a new SFC, wherein the SFC comprises a first service function (SF) that modifies packets in the session, the method comprising:

• determining to update a second SF in the SFC for the session;
• determining a new SFC for the session comprising new SFs, wherein the new SFs are selected based on the determined update to the second SF and information related to the packet modification performed by the first SF;
• and
• sending a first message to a session management function, SMF, comprising updated policy control rules for the session, wherein the updated policy control rules comprise an indication of the new SFC for the session.

A method in a session management function (SMF) of moving a session from a service function chain (SFC) to a new SFC, wherein the SFC comprises a first service function (SF) that modifies packets in the session, the method comprising:

• responsive to receiving a third message from a user plane function, UPF, associated with the session, the third message indicating that the first SF is modifying packets in the session, sending a second message to a policy control function (PCF) comprising a request for updated policy control rules for the session, wherein the second message comprises information related to the modification being performed by the first SF;
• receiving a first message from the PCF comprising the updated policy control rules for the session, wherein the updated policy control rules comprise an indication of a new SFC for the session, wherein the new SFC comprises new SFs selected by the PCF;
• and
• sending a fourth message to the UPF, the fourth message comprising the updated policy control rules for the session.

A method in a user plane function (UPF) of moving a session from a service function chain (SFC) to a new SFC, wherein the SFC comprises a first service function (SF) that modifies packets in the session, the method comprising:

• sending a third message to a session management function (SMF) the third message indicating that the first SF is modifying packets in the session;
• receiving from the SMF a fourth message, the fourth message comprising updated policy control rules for the session, wherein the updated policy control rules comprise an indication of a new SFC for the session;
• and
• moving the session from the SFC to the new SFC, based on the received updated policy control rules.