Access Device Failover for Cloud Network Disconnection Recovery
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Solution Overview
Problem
When a cloud-controlled and managed access device loses connectivity with its cloud controller due to faults or bugs, it disrupts layer 3 connectivity, preventing LAN devices from accessing the Internet, and traditional rebooting or manual intervention is ineffective.
Innovation Solution
The access device implements a dual network service system, including a main network service with cloud CaC functionality and a backup service without cloud interaction, allowing it to automatically switch to the backup service upon loss of connectivity, thereby maintaining layer 3 connectivity through a reboot process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the access device uses cloud-controlled network management, then network management functionality is improved, but connectivity reliability deteriorates when cloud controller fails
Solution Approach 1:
The network service is segmented into a main network service that interfaces with the cloud controller and a backup network service that operates independently. This segmentation allows the access device to maintain connectivity through the backup service when the main service loses cloud connectivity, resolving the contradiction between advanced cloud management and connectivity reliability.
Solution Approach 2:
The backup network service acts as an intermediary fallback mechanism. When the main network service cannot communicate with the cloud controller, the backup service mediates by providing alternative network management functionality, ensuring continuous operation without complete dependency on the cloud controller.
2Reliability
If the access device implements automatic failover to backup service, then connectivity reliability is improved, but device complexity increases
Solution Approach 1:
The backup network service is pre-configured and ready before any failure occurs. The access device maintains the ability to switch to the backup service without needing to analyze failure conditions in real-time, as the failover mechanism is prepared in advance. This preliminary preparation reduces the complexity of implementing automatic failover.
Solution Approach 2:
The access device automatically monitors its own connectivity status and initiates failover to the backup service without external intervention. This self-service capability simplifies the overall system architecture by eliminating the need for complex external monitoring and control mechanisms.
3Speed
If the access device continuously monitors network connectivity, then response time to failures is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous monitoring, the access device performs periodic connectivity checks to the cloud controller. This periodic action provides sufficient response time for failure detection while significantly reducing energy consumption compared to continuous monitoring, resolving the contradiction between fast failure response and energy efficiency.
Data Source
AI summary
An access device communicatively coupled to a local area network (LAN) and to an aggregation device in a service provider network establishes layer 3 connectivity with the service provider network via a main network service. Subsequent to establishing layer 3 connectivity to the service provider network, the access device determines that the main network service has lost layer 3 connectivity to the service provider network. The access device attempts to re-establish layer 3 connectivity with the service provider network using a backup network service.