Dual-Homing Port Selection via Peer Status Feedback
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Solution Overview
Problem
Dual-homing access technologies experience overprotection due to delay policies, leading to unnecessary network transmission interruptions when both network side devices implement delay policies simultaneously, causing both ports to be in a non-operational state.
Innovation Solution
A method is introduced where network devices determine the status of both ports and selectively switch one port to an operational state, skipping the delay state to ensure continuous network connectivity by advertising port statuses using protocols like RISAP or VRRP, allowing the access side device to maintain connectivity without both ports being in a non-operational state at the same time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If delay policy is implemented on both network side devices to prevent frequent intermittent disconnections, then network stability is improved, but network transmission is unnecessarily interrupted when both ports enter delay state simultaneously
Solution Approach 1:
The patent implements a feedback mechanism where network devices advertise their port statuses to each other using protocols like RISAP or VRRP. When one device detects that its peer's port is in delay state, it receives this status information and adjusts its own port state accordingly, skipping the delay state to maintain network connectivity. This feedback loop prevents both ports from being in delay state simultaneously, resolving the contradiction between stability and continuity.
Solution Approach 2:
The patent introduces dynamic state adjustment where port states are not fixed but can be adaptively changed based on real-time network conditions. When a port would normally enter delay state, it dynamically checks the peer's status and transitions directly to UP state if needed, making the system flexible enough to prevent simultaneous delay states while maintaining the protective function of delay policies.
2Reliability
If delay policy is used to gain recovery time when network side device restarts, then system recovery capability is improved, but traffic interruption occurs when both devices implement delay policy at the same time
Solution Approach 1:
During device restart scenarios, the feedback mechanism allows the recovering device to detect when its peer is already in delay state or has recovered. The recovering device uses this information to skip its own delay state and transition directly to operational state, reducing traffic interruption time while still allowing the peer device to maintain its protective delay policy for system recovery.
Solution Approach 2:
The patent enables preliminary state adjustment where a device preparing to enter delay state first checks the peer's current status. If the peer is already recovering or in delay state, the device takes preliminary action to skip its own delay transition, preventing simultaneous delay states and minimizing traffic loss during restart scenarios.
Data Source
AI summary
A port selection method applied to a first network device and a second network device includes determining that a port status of a first port that is in the first network device and that is used for dual-homing access can switch from a first state to an UP state; receiving a port status of a second port that is in the second network device and that is used for dual-homing access; and selecting, based on the port status of the first port and the port status of the second port, a port to be switched to the UP state from the first port and the second port.