Wireless Access Tunnel Redundancy Across Fabric Edges
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Solution Overview
Problem
Existing software-defined access (SDA) networks lack seamless and rapid link and access tunnel redundancy for wireless client devices connected to access points (APs) behind extended nodes (ENs) and policy extended nodes (PENs), leading to potential traffic disruptions during link or node failures.
Innovation Solution
Implement a fast active-standby link redundancy mechanism using an Extended Node (EN) or Policy Extended Node (PEN) to provision dual-homed access tunnels with active and standby roles, enabling seamless traffic steering to a standby fabric edge node upon detecting failures, utilizing a virtual IP address for uninterrupted communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single active access tunnel is used for wireless client devices, then network configuration is simple, but network reliability deteriorates during link or node failures
Solution Approach 1:
The patent pre-configures both active and standby access tunnels before failures occur. The standby tunnel is established in advance with a standby fabric edge node, so that when a failure occurs, the system can immediately switch to the pre-prepared standby tunnel without needing to establish a new connection, thus improving reliability while maintaining manageable complexity through automation.
Solution Approach 2:
The extended node (EN) acts as an intermediary that automatically detects failures and triggers the switch from active to standby tunnels. This intermediary component simplifies the overall system by centralizing the failure detection and tunnel switching logic, reducing the complexity that would otherwise be distributed across multiple devices.
2Speed
If manual tunnel switching is implemented upon failure, then configuration is simple, but convergence time increases导致 traffic disruptions
Solution Approach 1:
The system implements automatic feedback mechanisms where the extended node continuously monitors the health of active tunnels and fabric edge nodes. When a failure is detected, the system automatically triggers the switching process without human intervention. This feedback-driven automation achieves rapid convergence while maintaining manageable complexity through centralized control.
Solution Approach 2:
The network system performs self-service by automatically detecting failures and executing tunnel switching without requiring manual configuration or intervention. The standby tunnel is automatically activated when needed, enabling fast convergence while the automation is managed through predefined policies and automated protocols.
3Reliability
If access tunnel redundancy is implemented for wireless clients, then network availability improves, but system complexity increases
Solution Approach 1:
The system segments the redundancy functionality by introducing extended nodes (ENs) as dedicated components that handle failure detection and tunnel switching. This segmentation isolates the complexity of redundancy management to specific network elements rather than requiring all devices to implement complex redundancy logic, thereby improving availability while containing system complexity.
Solution Approach 2:
The extended node serves multiple functions: it acts as a gateway for wireless clients, monitors tunnel health, detects failures, and triggers switching to standby tunnels. This multi-functionality consolidates redundancy management capabilities into a single component, improving network availability while avoiding the need for each device to independently implement complex redundancy mechanisms.
Data Source
AI summary
In an overlay access network, a first access tunnel between a first fabric edge node and a wireless access point (AP) can be configured as active, based on the first fabric edge node being active. A second access tunnel between a second fabric edge node and the wireless AP can be configured as standby based on the second fabric edge node being standby, with the same virtual IP address attached to the first and second access tunnels. Based on an active failure, a switch to standby for the first fabric edge node and to active for the second fabric edge node is signaled to an Extended Node (EN). The EN steers traffic on the first access tunnel with the virtual IP address to the second fabric edge node, based on the switch and using a portion of the second access tunnel between the EN and the second fabric edge node.