Session Redundancy Using a Replay Model

• US 20090006879A1
• Filed: 08/20/2007
• Published: 01/01/2009
• Est. Priority Date: 06/30/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Foltak, Richard, Haag, Jeffrey David, Henderson, Samuel G., Harris, Gary Lee
• Granted Patent: US 8,074,094 B2
• Time in Patent Office: Days
• US Class Current: 713/375
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/021 Ensuring consistency of routing table updates, e.g. by using epoch numbers
• CPC Class Codes: H04L 45/308 Route determination based on user's profile, e.g. premium users
• CPC Class Codes: H04L 45/56 Routing software
• CPC Class Codes: H04L 45/586 of virtual routers
• CPC Class Codes: H04L 45/64 using an overlay routing layer
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 67/142 Managing session states for stateless protocols; Signalling session states; State transitions; Keeping-state mechanisms

Abstract

A mechanism for synchronizing states of components in a first routing engine to corresponding components in a second routing engine is provided. In order to reduce the amount of data required to synchronize the state of the components and the time and resources required to perform the synchronization, the state-related information transmitted from the first routing engine to the second routing engine is limited to information used to build states of a subset of the components associated with the first routing engine. That subset of components is limited to those components that receive stimuli (e.g., data streams or data packets) from sources external to the routing engine. Other components on the second routing engine synchronize state by receiving information from those components on the second routing engine that received the external stimuli information.

Claims

1. An apparatus comprising:

a first processor comprising a first plurality of components; and

a second processor, coupled to the first processor, comprising a second plurality of components, wherein

the first and second processors are configured to synchronize state information of each component of the first processor with counterpart components of the second processor,

said synchronizing comprises transmitting information used to establish states of a first subset of the first plurality of components from the first processor to counterpart components of the second processor, and

the first subset comprises less than all of the components of the first plurality of components.

2. The apparatus of claim 1 wherein the first subset comprises:

a component that receives stimuli from a source external to the first plurality of components, wherein

the stimuli are used by the component to establish the state of that component.

3. The apparatus of claim 2 wherein the stimuli comprises a data stream.

4. The apparatus of claim 1, wherein

a second subset of the second plurality of components corresponds to the first subset;

and

each component of a remainder of the second plurality of components establishes a state of that component using information received from one or more components of the second subset, wherein

the remainder of the second plurality of components comprises components that are not members of the second subset.

5. The apparatus of claim 1 wherein the first and second processors are further configured to perform said synchronizing state information on a per session basis.

6. The apparatus of claim 1 wherein said synchronizing provides each component of the second plurality of components with a state substantially the same as that of each corresponding component in the first plurality of components.

7. The apparatus of claim 1 wherein said synchronizing further comprises:

providing the information used to establish the state of a component of the first subset to a corresponding component of the second plurality of components in the same order provided to the component of the first subset.

8. A method comprising:

establishing states of a first plurality of components; and

synchronizing states of a second plurality of components with states of corresponding components in the first plurality of components, wherein said synchronizing comprises

transmitting information used to establish state of a subset of the first plurality of components to corresponding components in the second plurality of components, wherein

the subset comprises fewer than all the components of the first plurality of components.

9. The method of claim 8 wherein said establishing the states of the first plurality of components comprises:

determining a state of a first component of the first plurality of components using first information received by the first component from a remote source; and

determining a state of a second component of the first plurality of components using second information received by the second component from the first component.

10. The method of claim 9 wherein said transmitting information comprises:

providing the first information to a first counterpart component in the second plurality of components of the first component; and

establishing a state of a second counterpart component in the second plurality of components of the second component using third information received from the first counterpart component.

11. The method of claim 10 wherein the first information is less than all the information received from the remote source.

12. The method of claim 10 wherein the first information comprises only that information used to establish the state of the first component.

13. The method of claim 9 wherein said establishing the state of the first component further comprises:

executing configuration instructions prior to receiving the first information.

14. The method of claim 13 wherein said synchronizing further comprises:

providing the configuration instructions executed by the first component to the first counterpart component prior to said providing the first information to the first counterpart component.

15. An apparatus comprising:

means for establishing states of a first plurality of components; and

means for synchronizing states of a second plurality of components with states of corresponding components in the first plurality of components, wherein said means for synchronizing comprises

means for transmitting information used to establish state of a subset of the first plurality of components to corresponding components in the second plurality of components, wherein

the subset comprises fewer than all the components of the first plurality of components.

16. The apparatus of claim 15 wherein said means for establishing the states of the first plurality of components comprises:

means for determining a state of a first component of the first plurality of components using first information received by the first component from a remote source; and

means for determining a state of a second component of the first plurality of components using second information received by the second component from the first component.

17. The apparatus of claim 16 wherein said means for transmitting information comprises:

means for providing the first information to a first counterpart component in the second plurality of components of the first component; and

means for establishing a state of a second counterpart component in the second plurality of components of the second component using third information received from the first counterpart component.

18. The apparatus of claim 17 wherein the first information comprises only that information used to establish the state of the first component.

19. The apparatus of claim 16 wherein said means for establishing the state of the first component further comprises:

means for executing configuration instructions prior to receiving the first information.

20. The apparatus of claim 19 wherein said means for synchronizing further comprises:

means for providing the configuration instructions executed by the first component to the first counterpart component prior to said providing the first information to the first counterpart component.