Multicast State Synchronization via Incremental Opcodes
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Solution Overview
Problem
Multicast routing services are interrupted during a switchover in network devices due to the rebuilding of multicast state information, which can take several seconds or minutes, and relies on information from neighboring devices, causing downtime and dependency on GenID processing.
Innovation Solution
Implementing incremental updates to synchronize multicast information between active and standby processors, allowing for non-stop routing (NSR) by reducing the number of opcodes needed for updates and enabling the standby processor to take over without rebuilding state information from scratch, thus eliminating the need for GenID processing and reducing dependency on neighboring devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the standby processor rebuilds multicast state information from scratch during switchover, then the system ensures data consistency, but the switchover time increases to several seconds or minutes causing service interruption
Solution Approach 1:
The standby processor performs preliminary synchronization by receiving and processing incremental updates from the active processor before switchover occurs. This allows the standby to have partially or fully synchronized multicast state information in advance, eliminating the need to rebuild from scratch during actual switchover.
Solution Approach 2:
The patent extracts only the essential multicast state information changes (represented as opcodes) from the active processor and transfers them to the standby processor. This selective extraction of critical data elements enables fast synchronization without transferring complete state information.
2Productivity
If the system uses complete state information transfer during switchover, then the standby processor can take over immediately, but the network device complexity and dependency on neighboring devices increase
Solution Approach 1:
The multicast state information is segmented into discrete opcode elements that represent individual changes or updates. Instead of transferring complete state information, only these segmented opcode elements are transmitted, reducing the amount of data and simplifying the synchronization process.
Solution Approach 2:
The patent changes the parameter representation of state information from complete data structures to compact opcode indicators. This parameter transformation enables efficient transmission and processing while maintaining the ability to reconstruct or apply state changes at the standby processor.
3Reliability
If the standby processor waits for complete synchronization before taking over, then multicast service continuity is maintained, but the downtime during switchover increases
Solution Approach 1:
The incremental update mechanism enables continuous synchronization between active and standby processors during normal operation. This continuous useful action ensures the standby processor is always partially or fully synchronized, allowing immediate takeover without service interruption when switchover is needed.
Data Source
AI summary
Techniques that enable a network device such as a router to provide multicast routing services without interruption, even in the event of a switchover. An incremental updates technique is used to synchronize multicast information maintained by a first processor and multicast information maintained by a second processor. The first processor may be a management processor operating in active mode in a network device and the second processor may be a management processor operating in standby mode in the network device. The second processor may also be a processor on a linecard of the network device.