Cisco Technology, Inc.

Denis Leclerc

Donald Edward Banks

Timothy Patrick Donahue

Balachander Chandrasekaran

Thomas W Uban

Vijay J Savla

A system and method for supporting a 'hitless' switchover from an Active to a Standby processor uses a hybrid synchronization of interface states to allow applications that have been modified to have HA aware features and non-modified applications to function on the system. An interface description data block on the Standby RP is synchronized to the interface description data block on the Active RP and is maintained in a shadow state when the Active RP controls the system. In the event of a switchover between the RPs the interface description data block on the Standby RP is copied from the shadow state to a real state and applications on the Standby RP are notified of a status change.

Hybrid interface synchronization method and driver-client model for high availability systems

A method is disclosed for providing interoperation of a first execution image of a first version and a second execution image of a second version. A compatibility matrix specifies whether the versions are compatible, base-level compatible, or incompatible. In one embodiment, the compatibility matrix may comprise a sparse table that stores a compatibility indicator for all permutations of a plurality of versions of a network operating system. As part of initialization of a system that includes the first execution image and second execution image, version information for the execution images is determined. An entry in the compatibility matrix corresponding to the versions is identified. The execution images are operated in a fully synchronized state when the identified entry of the compatibility matrix specifies that the versions are either compatible or base-level compatible. Individual components of the execution images interoperate according to the results of individual session negotiations. If the versions are incompatible, an alternative redundancy operation mode may be used. Embodiments provide for negotiation of compatible message versions and capabilities among peer components or clients of the execution images as source information to generate the compatibility matrix.

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Sterling, MA, United States of America

Denis Leclerc