Mobile gateways in pool for session resilience

1. A method in a first packet data network gateway (PDN-GW) in a PDN-GW pool of a plurality of PDN-GWs providing data connectivity between user equipment (UE) devices and an external PDN, wherein the first PDN-GW is communicatively coupled to a second PDN-GW in the PDN-GW pool, the method for providing UE session resilience by allowing the first PDN-GW to provide connectivity for a UE session previously serviced by the second PDN-GW after the second PDN-GW becomes non-operational, the method comprising:

receiving, from the second PDN-GW, a Create Session Request message for the UE session, wherein the second PDN-GW received another Create Session Request message for the UE session from a Serving Gateway (SGW), and wherein the second PDN-GW is to become the active PDN-GW for the UE session;

transmitting, to the SGW, a Create Session Response message indicating that the first PDN-GW will be a standby PDN-GW for the UE session and further indicating an Internet Protocol (IP) address of the first PDN-GW;

receiving, from the second PDN-GW, session information of the UE session; and

responsive to detecting that the second PDN-GW has entered or is about to enter into a non-operational state, switching to become the active PDN-GW for the UE session.

2. The method according to claim 1 , wherein said switching to become the active PDN-GW for the UE session comprises:

transmitting, to the SGW, a message indicating that the first PDN-GW is now the active PDN-GW for the UE session.

3. The method according to claim 1 , wherein said switching to become the active PDN-GW for the UE session comprises:

establishing a temporary data tunnel between the first PDN-GW and the second PDN-GW;

receiving, over the temporary data tunnel, traffic of the UE session from the second PDN-GW;

receiving additional traffic of the UE session from the SGW, wherein the additional traffic is not also received by the second PDN-GW; and

removing the temporary data tunnel.

4. The method according to claim 1 , wherein responsive to detecting that the second PDN-GW has entered or is about to enter into the non-operational state, the method further comprises switching to become the active PDN-GW for a second UE session, wherein the second PDN-GW was the active PDN-GW for the second UE session, and wherein the second PDN-GW was also the active PDN-GW for a plurality of other UE sessions that a third PDN-GW is the standby PDN-GW for.

5. The method according to claim 1 , wherein said detecting that the second PDN-GW has entered or is about to enter into the non-operational state comprises:

transmitting status inquiry messages to the second PDN-GW; and

detecting that the second PDN-GW did not respond to one of the status inquiry messages.

6. The method according to claim 1 , wherein said detecting that the second PDN-GW has entered or is about to enter into the non-operational state comprises:

receiving, from the second PDN-GW, a message indicating that it is about to enter into the non-operational state.

7. A first packet data network gateway (PDN-GW) to be used in a PDN-GW pool of a plurality of PDN-GWs to provide data connectivity between user equipment (UE) devices and an external PDN, wherein the first PDN-GW is to be communicatively coupled to a second PDN-GW in the PDN-GW pool, wherein the first PDN-GW is to provide UE session resilience by allowing the first PDN-GW to provide connectivity for a UE session previously serviced by the second PDN-GW after the second PDN-GW becomes non-operational, the first PDN-GW comprising:

a processor;

a memory;

a set of one or more ports coupled to the processor and to be coupled to the second PDN-GW, the set of ports configured to,

receive, from the second PDN-GW, a Create Session Request message for the UE session, wherein the second PDN-GW received another Create Session Request message for the UE session from a Serving Gateway (SGW), and wherein the second PDN-GW is to become the active PDN-GW for the UE session,

transmit, to the SGW, a Create Session Response message indicating that the first PDN-GW will be a standby PDN-GW for the UE session and further indicating an Internet Protocol (IP) address of the first PDN-GW, and

receive, from the second PDN-GW, session information of the UE session; and

a session resilience module configured to,

detect that the second PDN-GW has entered or is about to enter into a non-operational state, and

switch to become the active PDN-GW for the UE session.

8. The first PDN-GW according to claim 7 , wherein, to switch to become the active PDN-GW for the UE session, the session resilience module further is to utilize the set of ports to transmit, to the SGW, a message indicating that the first PDN-GW is now the active PDN-GW for the UE session.

9. The first PDN-GW according to claim 7 , wherein, to switch to become the active PDN-GW for the UE session, the session resilience module further is to utilize the set of ports to:

establish a temporary data tunnel between the first PDN-GW and the second PDN-GW;

receive, over the temporary data tunnel, traffic of the UE session from the second PDN-GW;

receive additional traffic of the UE session from the SGW, wherein the additional traffic is not also received by the second PDN-GW; and

remove the temporary data tunnel.

10. The first PDN-GW according to claim 7 , wherein the session resilience module, responsive to the detection that the second PDN-GW has entered or is about to enter into the non-operational state, is further to switch to become the active PDN-GW for a second UE session, wherein the second PDN-GW was the active PDN-GW for the second UE session, and wherein the second PDN-GW was also the active PDN-GW for a plurality of other UE sessions that a third PDN-GW is the standby PDN-GW for.

11. The first PDN-GW according to claim 7 , wherein the session resilience module, to detect that the second PDN-GW has entered or is about to enter into the non-operational state, is configured to:

utilize the set of ports to transmit status inquiry messages to the second PDN-GW; and

detect that the second PDN-GW did not respond to one of the status inquiry messages.

12. The first PDN-GW according to claim 7 , wherein the session resilience module, to detect that the second PDN-GW has entered or is about to enter into the non-operational state, is configured to utilize the set of ports to:

receive, from the second PDN-GW, a message indicating that it is about to enter into the non-operational state.

13. A method in a first packet data network gateway (PDN-GW) in a PDN-GW pool of a plurality of PDN-GWs providing data connectivity between user equipment (UE) devices and an external PDN, wherein the first PDN-GW is communicatively coupled to a second PDN-GW in the PDN-GW pool, the method for providing UE session resilience by allowing a second PDN-GW to provide connectivity for a UE session previously serviced by the first PDN-GW after the first PDN-GW becomes non-operational, the method comprising:

receiving, from a Serving Gateway (SGW), a Create Session Request message for the UE session;

transmitting, to the SGW, a Create Session Response message indicating that the first PDN-GW will act as an active PDN-GW for the UE session and further indicating an Internet Protocol (IP) address of the first PDN-GW;

transmitting, to the second PDN-GW, a second Create Session Request message to cause the second PDN-GW to act as a standby PDN-GW for the UE session and to transmit a second Create Session Response message to the SGW indicating that the second PDN-GW will act as the standby PDN-GW for the UE session and further indicating an IP address of the second PDN-GW;

transmitting, to the second PDN-GW, session information of the UE session; and

entering a non-operational state, causing the second PDN-GW to switch to become the active PDN-GW for the UE session.

14. The method according to claim 13 , wherein the entering the non-operational state comprises:

establishing a temporary data tunnel between the first PDN-GW and the second PDN-GW;

transmitting, over the temporary data tunnel, traffic of the UE session to the second PDN-GW; and

removing the temporary data tunnel.

15. The method according to claim 13 , wherein the first PDN-GW is further communicatively coupled to a third PDN-GW in the PDN-GW pool, wherein the method further comprises:

receiving, from the SGW, a third Create Session Request message for a second UE session;

transmitting, to the SGW, a third Create Session Response message indicating that the first PDN-GW will act as the active PDN-GW for the second UE session;

transmitting, to the third PDN-GW, a third Create Session Request message to cause the third PDN-GW to act as the standby PDN-GW for the second UE session and to transmit a fourth Create Session Response message to the SGW indicating that the third PDN-GW will act as the standby PDN-GW for the second UE session;

transmitting, to the third PDN-GW, session information of the second UE session; and

wherein the entering the non-operational state further causes the third PDN-GW to switch to become the active PDN-GW for the second UE session.

16. The method according to claim 15 , wherein entering the non-operational state comprises:

establishing a first temporary data tunnel between the first PDN-GW and the second PDN-GW and a second temporary data tunnel between the first PDN-GW and the third PDN-GW;

transmitting, over the first temporary data tunnel, traffic of the UE session to the second PDN-GW;

transmitting, over the second temporary data tunnel, traffic of the second UE session to the third PDN-GW; and

removing the first temporary data tunnel and the second temporary data tunnel.

17. A first packet data network gateway (PDN-GW) to be used in a PDN-GW pool of a plurality of PDN-GWs to provide data connectivity between user equipment (UE) devices and an external PDN, wherein the first PDN-GW is to be communicatively coupled to a second PDN-GW in the PDN-GW pool, wherein the first PDN-GW is to provide UE session resilience by allowing the second PDN-GW to provide connectivity for a UE session previously serviced by the first PDN-GW after the first PDN-GW becomes non-operational, the first PDN-GW comprising:

a set of one or more ports to communicatively couple the first PDN-GW to a network;

a session resilience module coupled to the set of ports and configured to,

receive, from a Serving Gateway (SGW), a Create Session Request message for the UE session,

transmit, to the SGW, a Create Session Response message indicating that the first PDN-GW will act as an active PDN-GW for the UE session and further indicating an Internet Protocol (IP) address of the first PDN-GW, transmit, to the second PDN-GW, a second Create Session Request message to cause the second PDN-GW to act as a standby PDN-GW for the UE session and to transmit a second Create Session Response message to the SGW indicating that the second PDN-GW will act as the standby PDN-GW for the UE session and further indicating an IP address of the second PDN-GW, and

transmit, to the second PDN-GW, session information of the UE session; and

wherein the first PDN-GW, upon entering a non-operational state, causes the second PDN-GW to switch to become the active PDN-GW for the UE session.

18. The first PDN-GW of claim 17 , wherein the session resilience module, upon the first PDN-GW beginning to enter the non-operational state, is further configured to:

establish a temporary data tunnel between the first PDN-GW and the second PDN-GW;

transmit, over the temporary data tunnel, traffic of the UE session to the second PDN-GW; and

remove the temporary data tunnel.

19. The first PDN-GW of claim 17 , wherein:

the session resilience module is further configured to:

receive, from the SGW, a third Create Session Request message for a second UE session,

transmit, to the SGW, a third Create Session Response message indicating that the first PDN-GW will act as the active PDN-GW for the second UE session,

transmit, to the third PDN-GW, a third Create Session Request message to cause the third PDN-GW to act as the standby PDN-GW for the second UE session and to transmit a fourth Create Session Response message to the SGW indicating that the third PDN-GW will act as the standby PDN-GW for the second UE session, and

transmit, to the third PDN-GW, session information of the second UE session; and

the first PDN-GW, upon entering the non-operational state, further causes the third PDN-GW to switch to become the active PDN-GW for the second UE session.

20. The first PDN-GW of claim 19 , wherein the session resilience module, upon the first PDN-GW beginning to enter the non-operational state, is further configured to:

establish a first temporary data tunnel between the first PDN-GW and the second PDN-GW and a second temporary data tunnel between the first PDN-GW and the third PDN-GW;

transmit, over the first temporary data tunnel, traffic of the UE session to the second PDN-GW;

transmit, over the second temporary data tunnel, traffic of the second UE session to the third PDN-GW; and

remove the first temporary data tunnel and the second temporary data tunnel.