Tunnel Endpoint Identifier for SDN Routing Stability
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Solution Overview
Problem
In software-defined networking (SDN) environments, tunnel-based routing calculations face challenges such as tunnel flapping, which affects cross-site connectivity and network performance due to dynamic routing protocol sessions and route advertisements between network devices.
Innovation Solution
Implementing a method to retain specific routes in tunnel-based routing calculations, using techniques like configuring next hops and filtering BGP sessions to prevent frequent changes in tunnel availability, thereby stabilizing tunnel connections and reducing downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic routing protocol sessions and route advertisements are used between network devices, then routing adaptability and network flexibility are improved, but tunnel stability deteriorates due to frequent route changes and tunnel flapping
Solution Approach 1:
The patent introduces a tunnel endpoint identifier (TEP) as an intermediary between the routing protocol and the tunnel interface. The TEP acts as a stable anchor point that decouples the dynamic routing advertisements from the tunnel establishment process. Routes are advertised to TEPs rather than directly to tunnel interfaces, allowing the routing protocol to remain dynamic while tunnel endpoints maintain stability. This mediator absorbs the variability of route changes without propagating them to the tunnel layer.
Solution Approach 2:
The patent segments the routing information into two distinct components: stable tunnel endpoint identifiers (TEPs) and dynamic route advertisements. By separating the tunnel establishment function from the route advertisement function, the system allows routing protocols to dynamically advertise routes to specific TEPs without causing tunnel flapping. This segmentation enables independent optimization of routing flexibility and tunnel stability.
2Loss of information
If route advertisements are freely exchanged between tunnel interfaces, then routing information completeness is improved, but tunnel flapping increases due to conflicting route preferences
Solution Approach 1:
The patent applies local quality by making tunnel interfaces selectively receptive to route advertisements based on their specific role and configuration. Instead of uniformly accepting all route advertisements, each tunnel interface is configured with specific criteria for which routes to accept or reject. This localized filtering ensures that routing information completeness is maintained for legitimate routes while preventing conflicting advertisements that would cause tunnel flapping.
Solution Approach 2:
The TEP serves as an intermediary that receives and validates route advertisements before they are propagated to tunnel interfaces. This mediator layer filters out conflicting or inappropriate route advertisements, ensuring that only valid routing information reaches the tunnel interfaces. The TEP thus prevents information loss of legitimate routes while blocking harmful advertisements that would cause instability.
3Productivity
If tunnel routes are dynamically updated based on routing protocol advertisements, then network performance optimization is improved, but cross-site connectivity reliability deteriorates due to tunnel flapping
Solution Approach 1:
The patent performs preliminary actions by pre-establishing stable TEPs before dynamic route advertisements are processed. The TEPs are configured in advance as stable anchor points, and routing protocols are then directed to advertise routes to these pre-established endpoints. This preliminary setup ensures that even as routes dynamically update for performance optimization, the underlying tunnel connectivity remains stable and reliable.
Solution Approach 2:
The TEP acts as a mediator that decouples performance optimization from connectivity stability. Routing protocols can dynamically optimize routes by advertising different paths to TEPs based on network conditions, while the tunnel interfaces maintain stable connections to their configured TEPs. This intermediary layer allows network performance to be optimized through dynamic routing without compromising cross-site connectivity reliability.
Data Source
AI summary
Example methods and network devices for tunnel-based routing calculation. One example method may comprise establishing a tunnel between a first tunnel interface and a second tunnel interface; establishing a first session for routing information exchange between a first tunnel endpoint and an underlay network device; establishing a second session for routing information exchange between the first tunnel interface and the second tunnel interface over the tunnel. In response to receiving first routing information over the first session, the underlay network device may be configured to be a next hop to reach the second tunnel endpoint by updating a routing table to include a first entry. Further, the underlay network device may be retained as the next hop by updating the routing table to include a second entry to override second routing information that advertises, over the second session, the second tunnel interface as the next hop.