Stateful Session Rerouting Through Intentional Path Change
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Solution Overview
Problem
Conventional routers fail to efficiently reroute stateful routing sessions when a path fails, leading to prolonged downtime and potential blackholing of traffic, especially in scenarios where IPsec tunnels are involved, without providing mechanisms for timely session reestablishment.
Innovation Solution
A router changes the network path for stateful routing sessions, causing the destination device to reject packets, prompting the source device to establish a new session, thereby avoiding the need for session timeouts and enabling faster rerouting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional router waits for session timeout to reroute stateful routing sessions, then the routing session can be reestablished, but the downtime is prolonged and traffic may be blackholed
Solution Approach 1:
The router proactively changes the network path for a routing session before the session times out. When the router detects that a first network path should no longer be used, it immediately forwards packets along a second network path, causing the destination device to reject the packets. This rejection prompts the source device to establish a new session before the original session times out, thereby avoiding prolonged downtime and preventing traffic blackholing.
2Speed
If a router changes the network path for stateful routing sessions, then rerouting is achieved, but the destination device must reject packets to prompt session reestablishment
Solution Approach 1:
The router intentionally causes packet rejection by changing the network path, converting a harmful effect (packet rejection) into a beneficial outcome (faster session reestablishment). By forwarding packets along a second network path that causes rejection, the router prompts the source device to establish a new session more quickly than waiting for timeout, thus improving rerouting speed while the packet rejection serves as a signal for session renewal.
3Adaptability or versatility
If conventional routers use non-stateful routing, then traffic can be redirected to alternate paths, but stateful routing sessions cannot be migrated selectively
Solution Approach 1:
The router segments traffic management by applying different routing strategies to different sessions. It maintains stateful routing for sessions that require path consistency while enabling selective path changes for sessions that can tolerate or benefit from path changes. This segmentation allows the router to manage complex session states while providing flexible path selection, resolving the contradiction between adaptability and complexity.
Data Source
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AI summary
As described herein, a router signals a source device to establish a new stateful communication session with a destination device by changing a network path used by traffic associated with the session. In one example, a router forwards traffic of a first stateful routing session established by the source device along a first path. In response to determining that that the first path should not be used, the router forwards a packet of the first session along a second path. The destination device recognizes the change in path, which causes the destination device to reject the packet, which in turn causes the source device to establish a second stateful routing session. The router forwards subsequent traffic of the second stateful routing session along the second path.