Dual Homed Access Network SPBM Virtual Tunnels
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Solution Overview
Problem
Conventional arrangements for defining multiple paths from a transport network to an access network suffer from potential routing loops, increased hops, and inconsistency with forwarding to different types of access networks, failing to leverage the ability of SPBM to support multiple paths and intercept traffic addressed to a shared virtual BMAC.
Innovation Solution
The implementation of dual homing in an SPBM enabled network using virtual tunnels across the transport network, where each partner switching device serves the access network, and routing logic designates primary and secondary paths only when faults occur, avoiding unnecessary hops and traffic redirection without faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multiple path arrangements are implemented, then fault tolerance is improved, but routing loops and increased hops occur
Solution Approach 1:
The system dynamically switches between active and standby paths based on fault conditions. The dual homed access network maintains a primary path for normal operation and a secondary path for failover, allowing the network to adapt its topology dynamically without creating permanent routing loops or unnecessary hops.
Solution Approach 2:
The patent applies different forwarding behaviors to different parts of the network. At the dual homed access network edge, both paths are available but only one is active. In the transport network, routing is optimized to avoid loops. This localized application of different qualities resolves the contradiction between fault tolerance and latency.
2Reliability
If dual homing is implemented with virtual tunnels, then fault tolerance is maintained, but device complexity increases
Solution Approach 1:
The dual homed access network uses a universal interface and addressing scheme (shared virtual BMAC) that works with different transport network configurations. The EVPN framework provides a universal control plane that simplifies the routing logic by abstracting the complexity of multiple paths and failover scenarios into standardized procedures.
Solution Approach 2:
The patent introduces EVPN as an intermediary control plane between the dual homed access network and the transport network. This intermediary handles the complex routing logic, path selection, and failover decisions centrally, reducing the complexity burden on individual forwarding devices while maintaining robust connectivity assurance.
3Adaptability or versatility
If conventional forwarding is used, then simplicity is maintained, but adaptability to different access network types is reduced
Solution Approach 1:
The EVPN framework provides a universal control plane that can adapt to different types of access networks (Ethernet, Wi-Fi, etc.) through a common interface. The dual homing mechanism works consistently across different access network types, providing adaptability without requiring complex type-specific forwarding logic at each device.
Data Source
AI summary
A transport network employs dual homing to an access network to provide connectivity from multiple network switches. Dual homing is a mechanism by which an access network employs pair of switches in the transport network as if it were connecting to a single device. Conventional arrangements for defining multiple paths from a transport network to an access network suffer from the shortcomings of potential routing loops, increased hops to the access network, and inability or inconsistency with forwarding to different types of access networks, and may involve redirecting traffic absent faults in the access network. The dual homed network switches identify the type of access network and perform switching logic corresponding to the access network type to provide comprehensive dual-homed support to the access network independently of the type of transport employed in the access network, and employ redirection only if there is a fault in the access network.