Multi-homing ISP Switchover via Zero-Lifetime Router Advertisements
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Solution Overview
Problem
In multi-homed information handling systems, client devices fail to switch traffic from a default router device to an alternative Internet service provider when the link between the default router and ISP goes down, due to IPv6 router advertisement standards that continue to declare the default router as available, causing dropped traffic.
Innovation Solution
A system that includes a default router determination engine to send router advertisements with zero lifetime information for the unavailable ISP, allowing client devices to select a new default router from available ISP systems, and includes security measures to prevent malicious router advertisements from triggering switchover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If IPv6 router advertisement standards are used to maintain default router availability, then network stability is improved, but traffic loss occurs when the link between default router and ISP goes down
Solution Approach 1:
The system performs preliminary detection of ISP link availability before traffic is sent. The determination engine checks whether the ISP is actually reachable through the default router, and only then allows the router to advertise itself as available. This prevents the contradiction by acting in advance to avoid the situation where stability mechanisms cause traffic loss.
Solution Approach 2:
The system implements a feedback mechanism where the determination engine continuously monitors ISP link status and provides this information to the router advertisement process. When the ISP becomes unavailable, the feedback loop triggers the router to stop advertising, thereby maintaining network stability while preventing traffic loss through real-time status updates.
2Ease of operation
If router advertisements continue to declare default router as available, then client devices maintain stable connections, but traffic is dropped when ISP link is down
Solution Approach 1:
The determination engine performs preliminary checks of ISP link status before the router advertises availability to client devices. This ensures that routers only declare themselves as available when they can actually deliver traffic to the ISP, preventing the scenario where connection stability mechanisms cause traffic drops.
Solution Approach 2:
A feedback mechanism is established where the determination engine continuously monitors ISP reachability and communicates this status to the router advertisement process. This feedback ensures that connection stability is maintained only when actual traffic delivery is possible, resolving the contradiction between ease of operation and reliability.
3Reliability
If switchover mechanism is implemented to detect unavailable ISP, then traffic can be redirected to alternative providers, but security risks from malicious router advertisements increase
Solution Approach 1:
The determination engine acts as an intermediary between the router and client devices, mediating the router advertisement process. It verifies ISP link status before allowing advertisements to be sent, thereby enabling reliable traffic switchover while filtering out potentially malicious advertisements. This intermediary role resolves the security vulnerability by adding a verification layer.
Solution Approach 2:
The system performs preliminary verification of ISP link availability through the determination engine before allowing router advertisements to be transmitted. This preliminary action ensures that only legitimate switchover events trigger advertisements, preventing malicious actors from exploiting the switchover mechanism while maintaining reliable traffic delivery.
4Difficulty of detecting and measuring
If neighbor detection is used to detect unavailable ISP, then link failures can be identified, but default router link-local address remains reachable causing traffic to be dropped
Solution Approach 1:
The invention extracts the ISP availability check from the local link detection scope and extends it to the remote ISP level. The determination engine actively tests whether the ISP is actually reachable beyond just checking if the default router's link-local address is responsive. This extraction of the detection function to a higher level resolves the contradiction by detecting true ISP unavailability while preventing traffic drops to unreachable destinations.
Data Source
AI summary
A multi-homing Internet service provider switchover system includes a plurality of Internet service provider systems and a respective router device coupled to each Internet service provider system. Each router device is configured to determine that a route to its respective Internet service provider system is unavailable and, in response, advertise as a non-default router device with router lifetime information and lifetime information for an address of its respective Internet service provider system set to zero. A client device receives a router advertisement from a first router device that was selected as a default router device, and determines that it includes lifetime information for an address of its first Internet service provider system set to zero. In response, the client device selects a second router device as the default router device such that traffic is switched from the first router device to the second router device.