Cisco Technology, Inc.

Vijay J Savla

Guy Fedorkow

Balachander Chandrasekaran

Donald Edward Banks

Timothy Patrick Donahue

John A Joyce

Kent H Hoult

Denis Leclerc

Nagarajan Swaminathan

Michael B Milano

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

To ensure fair access to upstream trunk bandwidth among a plurality of interface units, a plurality of queues is provided in a first unit. One of the queues is associated with the first interface unit. Each of the remaining queues is associated with one of a plurality of second interface units. Local data is received by the first interface unit and forwarded to the associated queue. Data received from a second, subtended interface unit is forwarded to a queue which associated with the second interface unit. Data is then issued from the queues according to a fairness algorithm. A unique identifier is assigned to each interface unit. Associating a queue with an interface unit is done by associating the queue with the respective interface unit's identifier. In each interface unit, local data is tagged with the instant interface unit's identifier, and received data is forwarded to a queue according to the data's tag. For ATM traffic, data can be tagged by inserting the receiving interface unit's identifier into the generic flow control (GFC) field. Alternatively, a table of associations between virtual channel identifiers (VCIs) and interface unit identifiers may be maintained, and the received data is forwarded to a queue according to the interface unit identifier associated with the data's VCI.

Ensuring fair access to upstream trunk bandwidth in ATM subtended configurations

Growing community of inventors

Nashua, NH, United States of America

Vijay J Savla