Keep-alive scheduler in a network device

• US 10,686,890 B2
• Filed: 03/29/2018
• Issued: 06/16/2020
• Est. Priority Date: 05/31/2016
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Inventors: Dutta, Rajib, Li, Michael, Maneti, Aravindu
• Primary Examiner(s): Choudhury, Azizul
• Application Number:
  US15/940,760
• Publication Number:
  US 20180295192A1
• Time in Patent Office: 810 Days
• CPC Class Codes: G06F 2009/45595 Network integration; Enabling network access in virtual machine instances
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects
• CPC Class Codes: H04L 43/103 with adaptive polling, i.e. dynamically adapting the polling rate
• CPC Class Codes: H04L 67/145 avoiding end of session, e.g. keep-alive, heartbeats, resumption message or wake-up for inactive or interrupted session
• CPC Class Codes: H04L 67/146 Markers for unambiguous identification of a particular session, e.g. session cookie or URL-encoding
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 67/61 taking into account QoS or priority requirements
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

A network device may execute a process (e.g., a software keep-alive process (SKAP)) that schedules the transmission of keep-alive messages or packets. The network device maintains a database of keep-alive network sessions storing information that is used for scheduling the transmission of the keep-alive messages or packets for the keep-alive network sessions. The database may be read and a next transmission time and session frequency for one or more keep-alive sessions may be determined. The one or more keep-alive sessions may then be placed in appropriate banks within a timer queue based on the determined next transmission time and session frequency. Each bank is associated with a time period from the current time. The keep-alive sessions having sooner next transmission times are placed in higher priority banks. The scheduler may allow for real-time scheduling of the one or more keep-alive sessions.

Claims

1. A method comprising:

executing on a network device a first virtual machine in an active mode and a second virtual machine in a standby mode;

reading a database configured to store data for a network session for the first virtual machine;

determining, using data read from the database, a next transmission time associated with the network session, wherein the next transmission time determines when to send a keep-alive packet for the network session;

determining that the next transmission time is within a next time period from a current time;

placing, based on determining that the next transmission time is within the next time period, an identifier for the network session in a first bank of a timer queue of the network device, wherein the first bank stores identifiers for network sessions for which keep-alive packets are to be sent upon termination of the next time period, wherein the timer queue executes external to the first virtual machine and the second virtual machine; and

after the first virtual machine fails, transmitting by the network device the keep-alive packet for the network session within the next time period, thereby preventing the network session from terminating.

2. The method of claim 1, wherein the data read from the database includes a previous transmission time and a transmission frequency, wherein a previous keep-alive packet was sent for the network session, and wherein the next transmission time is determined based on the previous transmission time and the transmission frequency.

3. The method of claim 1, wherein the timer queue further includes a second bank configured to store identifiers for network sessions for which keep-alive packets are to be sent within a subsequent time period following the next time period.

4. The method of claim 1, wherein the database is accessible by the first virtual machine and the second virtual machine, and the first and second virtual machines are executed by a line card of the network device.

5. The method of claim 4, wherein at least one of the first virtual machine or the second virtual machine stores data in the database for the network session.

6. The method of claim 4, wherein:

when the first virtual machine operates in the active mode, the first virtual machine performs a set of functions to facilitate forwarding of data packets from the network device; and

the second virtual machine operates in the standby mode while the first virtual machine operates in the active mode, wherein the second virtual machine does not perform the set of functions when operating in the standby mode.

7. The method of claim 1, wherein, when the next transmission time is before the current time, the identifier for the network session is placed in a highest priority bank.

8. The method of claim 1, further comprising:

switching the second virtual machine to the active mode from the standby mode after the first virtual machine fails.

9. The method of claim 8, wherein the keep-alive packet for the network session is transmitted before the second virtual machine switches to the active mode from the standby mode.

10. The method of claim 1, wherein the database is accessible by both the first virtual machine and the second virtual machine.

11. A network device comprising:

a first virtual machine in an active mode executing on the network device;

a second virtual machine in a standby mode executing on the network device;

a database configured to store data for one or more network sessions for the network device;

one or more processors executing a keep-alive subsystem process external to the first virtual machine and the second virtual machine, wherein the keep-alive subsystem process is configured to;

read the database;

determine, using data read from the database, a next transmission time associated with a network session from the one or more network sessions, wherein the next transmission time determines when to send a keep-alive packet for the network session;

determine that the next transmission time is within a next time period from a current time;

place, based on determining that the next transmission time is within the next time period, an identifier for the network session in a first bank of a timer queue of the network device, wherein the first bank stores identifiers for network sessions for which keep-alive packets are to be sent upon termination of the next time period; and

after the first virtual machine fails, transmit the keep-alive packet for the network session within the next time period, thereby preventing the network session from terminating.

12. The network device of claim 11, wherein the data read from the database includes a previous transmission time and a transmission frequency, wherein a previous keep-alive packet was sent for the network session, and wherein the next transmission time is determined based on the previous transmission time and the transmission frequency.

13. The network device of claim 11, wherein the timer queue further includes a second bank configured to store identifiers for network sessions for which keep-alive packets are to be sent within a subsequent time period following the next time period.

14. The network device of claim 11, wherein, when the next transmission time is before the current time, the identifier for the network session is placed in a highest priority bank.

15. The network device of claim 11, wherein the database is accessible by the first virtual machine and the second virtual machine, and the first and second virtual machines are executed by a line card of the network device.

16. The network device of claim 15, wherein at least one of the first virtual machine or the second virtual machine stores data for the one or more network sessions in the database.

17. The network device of claim 15, wherein:

when the first virtual machine operates in the active mode, the first virtual machine performs a set of functions to facilitate forwarding of data packets from the network device; and

the second virtual machine operates in the standby mode while the first virtual machine operates in the active mode, wherein the second virtual machine does not perform the set of functions when operating in the standby mode.

18. A non-transitory computer-readable media storing computer-executable instructions that, when executed by one or more computing devices, cause the one or more computing devices to:

execute on a network device a first virtual machine in an active mode and a second virtual machine in a standby mode;

read a database configured to store data for a network session for the first virtual machine;

determine, using data read from the database, a next transmission time associated with the network session, wherein the next transmission time determines when to send a keep-alive packet for the network session;

determine that the next transmission time is within a next time period from a current time;

place, based on determining that the next transmission time is within the next time period, a identifier for the network session in a first bank of a timer queue of the network device, wherein the first bank stores identifiers for network sessions for which keep-alive packets are to be sent upon termination of the next time period, wherein the timer queue executes external to the first virtual machine and the second virtual machine; and

after the first virtual machine fails, transmit by the network device the keep-alive packet for the network session within the next time period, thereby preventing the network session from terminating.

19. The non-transitory computer-readable media of claim 18, wherein the data read from the database includes a previous transmission time and a transmission frequency, wherein a previous keep-alive packet was sent for the network session, and wherein the next transmission time is determined based on the previous transmission time and the transmission frequency.

20. The non-transitory computer-readable media of claim 18, wherein the timer queue further includes a second bank configured to store identifiers for network sessions for which keep-alive packets are to be sent within a subsequent time period following the next time period.

21. The non-transitory computer-readable media of claim 18, wherein if the next transmission time is before the current time, the identifier for the network session is placed in a highest priority bank.

22. The non-transitory computer-readable media of claim 18, wherein the database is accessible by the first virtual machine and the second virtual machine, and the first and second virtual machines are executed by a line card of the network device.

23. The non-transitory computer-readable media of claim 22, wherein at least one of the first virtual machine or the second virtual machine stores data in the database for the network session.

24. The non-transitory computer-readable media of claim 22, wherein:

when the first virtual machine operates in the active mode, the first virtual machine performs a set of functions to facilitate forwarding of data packets from the network device; and

the second virtual machine operates in the standby mode while the first virtual machine operates in the active mode, wherein the second virtual machine does not perform the set of functions when operating in the standby mode.