Policy control function fallback
Systems, methods, and devices can be utilized for policy control function (PCF) fallback during the set up of a session utilizing a 5th Generation (5G) core network. An example method includes receiving, from a session management function (SMF), a request for a policy corresponding to a session. The request includes a first policy identifier corresponding to a first policy control function (PCF). The example method further includes determining that the first PCF is unavailable, generating a modified request by replacing the first policy identifier with a second policy identifier in the request. The second policy identifier corresponds to a second PCF. The example method also includes transmitting, to the second PCF, the modified second request.
1. A system, comprising:
one or more processors; and
a memory storing components executable by the one or more processors to perform operations comprising:
receiving, from a session management function (SMF), a first request for a policy corresponding to a session, the first request comprising a first policy identifier corresponding to a first policy control function (PCF);
determining that the first PCF is unavailable;
generating a modified first request by replacing the first policy identifier with a second policy identifier in the first request, the second policy identifier corresponding to a second PCF;
transmitting, to the second PCF, the modified first request;
receiving, from the SMF, a second request that requests the policy associated with the session;
transmitting, to the first PCF, the second request;
receiving, from the first PCF, a response that comprises the first policy identifier;
forwarding, to the SMF, the response;
transmitting, to the second PCF, the second request; and
receiving, from the second PCF, a second response that comprises the second policy identifier.
2. The system of claim 1 , wherein the one or more processors and the memory are comprised in at least one of a service communication proxy (SCP), a building support function (BSF), or an interworking function (IWF).
3. The system of claim 1 , wherein the modified first request comprises at least one of an Rx message originating from an Internet Protocol (IP) Multimedia Subsystem (IMS) network, a policy control update message, or a policy control delete message.
4. The system of claim 1 , wherein the memory comprises a datastore that comprises:
an entry comprising the first policy identifier, the second policy identifier, and an identifier of the session,
wherein generating the modified first request comprises:
identifying the entry based on the first policy identifier; and
identifying the second policy identifier based on the entry.
5. The system of claim 4 , wherein the entry further comprises a subscription permanent identifier (SUPI) and a data network name (DNN) of the session.
6. The system of claim 1 , wherein the session comprises a voice over new radio (VONR) session.
7. The system of claim 1 , the operations further comprising:
receiving, from the SMF, a third request that requests a change to the policy associated with the session, the third request comprising the first policy identifier;
transmitting, to the first PCF, the third request;
receiving, from the first PCF, a third response that comprises the first policy identifier;
transmitting, to the SMF, the third response;
generating a revised third request by replacing the first policy identifier with the second policy identifier in the third request;
transmitting, to the second PCF, the revised third request; and
receiving, from the second PCF, a fourth response that comprises the second policy identifier.
8. A method, comprising:
receiving, from a session management function (SMF), a first request for a policy corresponding to a session, the first request comprising a first policy identifier corresponding to a first policy control function (PCF);
determining that the first PCF is unavailable;
generating a modified first request by replacing the first policy identifier with a second policy identifier in the first request, the second policy identifier corresponding to a second PCF;
transmitting, to the second PCF, the modified first request;
receiving, from the SMF, a second request that requests a change to the policy associated with the session, the second request comprising the first policy identifier;
transmitting, to the first PCF, the second request;
receiving, from the first PCF, a response that comprises the first policy identifier;
transmitting, to the SMF, the response;
generating a revised second request by replacing the first policy identifier with the second policy identifier in the second request;
transmitting, to the second PCF, the revised second request; and
receiving, from the second PCF, a second response that comprises the second policy identifier.
9. The method of claim 8 , wherein the method is performed by at least one of a service communication proxy (SCP), a building support function (BSF), or an interworking function (IWF).
10. The method of claim 8 , wherein generating the modified first request comprises:
identifying, in a datastore, an entry comprising the first policy identifier, the second policy identifier, and an identifier of the session; and
identifying the second policy identifier based on the entry.
11. The method of claim 10 , wherein the entry further comprises a subscription permanent identifier (SUPI) and a data network name (DNN) of the session.
12. The method of claim 8 , wherein the session comprises a voice over new radio (VONR) session.
13. The method of claim 8 , further comprising:
receiving, from the second PCF, a third response based on the modified first request, the third response comprising the second policy identifier;
generating a modified third response by replacing the second policy identifier with the first policy identifier in the response; and
transmitting, to the SMF, the modified third response.
14. The method of claim 8 , the method further comprising:
receiving, from the SMF, a third request that requests the policy associated with the session;
transmitting, to the first PCF, the third request;
receiving, from the first PCF, a third response that comprises the first policy identifier;
forwarding, to the SMF, the third response;
transmitting, to the second PCF, the third request; and
receiving, from the second PCF, a fourth response that comprises the second policy identifier.
15. A system, comprising:
one or more processors; and
a memory storing components executable by the one or more processors to perform operations comprising:
receiving, from a session management function (SMF), a first SIP request that requests a policy associated with a voice session;
transmitting, to a first policy control function (PCF), the first SIP request;
receiving, from the first PCF, a first SIP response that comprises a first policy identifier corresponding to the policy of the voice session;
forwarding, to the SMF, the first SIP response;
receiving, from the SMF, a second SIP request that comprises the first policy identifier;
determining that a communication link with the first PCF is interrupted;
generating a modified second SIP request by replacing the first policy identifier with a second policy identifier in the second SIP request; and
transmitting, to a second PCF, the modified second SIP request.
16. The system of claim 15 , wherein the one or more processors and the memory are comprised in at least one of a service communication proxy (SCP), a building support function (BSF), or an interworking function (IWF).
17. The system of claim 15 , wherein the second SIP request comprises at least one of an Rx message originating from an Internet Protocol (IP) Multimedia Subsystem (IMS) network, a policy control update message, or a policy control delete message.