Stateful Switching Between Reliable Transport Modules
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Solution Overview
Problem
Current routing protocols, such as BGP and LDP, face challenges with fail-over in router processors, leading to expensive re-convergence and potential black-holing of traffic due to the loss of Transmission Control Protocol (TCP) sessions.
Innovation Solution
Implementing a stateful switching mechanism between primary and standby reliable transport modules, where both modules maintain the transport layer connection state, allowing seamless failover without restarting the connection, by replicating packets to both modules in the normal operating state and enabling the standby module to take over in case of failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fail-over occurs in a router processor running routing protocols, then the system can continue operating with alternative processors, but the TCP sessions go down causing expensive re-convergence and potential black-holing of traffic
Solution Approach 1:
The standby reliable transport protocol module is pre-configured and synchronized with the primary module before failure occurs. Packet reception is replicated to both modules in advance, so when fail-over happens, the standby module already has the necessary state information to continue TCP sessions without re-convergence, eliminating traffic black-holing and reducing downtime.
2Loss of time
If Graceful restart extensions of routing protocols are deployed, then re-convergence can be minimized, but the solution introduces its own problems and complexity
Solution Approach 1:
The invention segments the reliable transport protocol functionality into independent primary and standby modules. Each module maintains its own state, and the standby module is replicated separately from the primary. This segmentation allows the standby module to take over independently without requiring complex protocol extensions, simplifying the overall system while achieving graceful fail-over.
3Speed
If packet switching technology is used to achieve greater speed and capacity, then network performance improves, but reliable transport layer communication becomes more vulnerable to fail-over issues
Solution Approach 1:
The invention applies local quality by maintaining different states in the primary and standby modules. The standby module replicates the necessary connection state information locally, enabling it to continue packet switching operations independently. This allows high-speed packet switching to continue reliably during fail-over without requiring connection restarts, preserving both speed and reliability.
Data Source
AI summary
Disclosed are, inter alia, methods, apparatus, and means for stateful switching between reliable transport modules for communicating with an external peer without losing the transport layer connection. Primary and standby reliable transport protocol modules each maintain state concerning the reliable transport connection (e.g., data, segmentation, acknowledgements) such that if the primary or standby reliable transport protocol module fails, the other can resume by itself such that the communication with the peer transport application does not need to be restarted. Also, by the communications subsystem of a device providing copies of received reliable transport protocol messages directly to both the primary and standby reliable transport protocol modules, upon failover, the communications subsystem does not need to be reconfigured for resuming operations as, for example, the standby reliable transport protocol module will already be receiving these packets.