Transport Endpoint Segments for Inter-Domain Segment Routing Stability
Solution Overview
Problem
Traditional inter-domain segment routing techniques experience control plane churn due to changes in intra-domain tunnels, leading to unnecessary updates and cascading BGP updates, despite no end-to-end path changes.
Innovation Solution
The introduction of transport endpoint segments, which remain constant regardless of intra-domain tunnel changes, allowing dynamic binding to intra-domain tunnels and local updates at provisioning routers, eliminating the need for frequent updates to other routers or controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional inter-domain segment routing uses binding segment identifiers (BSIDs) of intra-domain tunnels, then the routing can be established, but control plane churn occurs when intra-domain tunnels change, causing unnecessary updates and cascading BGP updates
Solution Approach 1:
The patent segments the routing information into two distinct parts: transport endpoint segments (TES) with stable TESIDs that represent end-to-end transport services, and intra-domain tunnel segments with volatile BSIDs. This segmentation allows the stable TESIDs to be advertised internationally while the volatile intra-domain changes are contained locally, eliminating cascading BGP updates when tunnels change.
Solution Approach 2:
The transport endpoint segment acts as an intermediary between intra-domain tunnel changes and inter-domain routing. When intra-domain tunnels change, the TES remains bound to the new tunnel locally at the provisioning router without triggering external updates. This intermediary absorbs the changes and presents a stable interface to the rest of the network.
2Measurement precision
If intra-domain tunnel changes are propagated to other routers and controllers, then routing accuracy is maintained, but network-wide updates occur causing control plane churn and reduced efficiency
Solution Approach 1:
The patent applies local quality by allowing the provisioning router to maintain local knowledge of intra-domain tunnel bindings while advertising only the stable TESID externally. Other routers and controllers need only the stable TESID information, not the volatile intra-domain details. This local differentiation maintains routing accuracy where needed while improving overall network efficiency by minimizing unnecessary updates.
3Stability of the object's composition
If a constant transport endpoint SID is used across intra-domain tunnel changes, then control plane churn is reduced, but dynamic adaptation to tunnel changes requires local binding updates
Solution Approach 1:
The provisioning router performs self-service by automatically detecting intra-domain tunnel changes and re-binding the TES to new tunnels without external intervention. The router monitors its own intra-domain routing state and updates the TES binding locally, eliminating the need for external controllers to manage these changes while maintaining TESID stability.
Data Source
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AI summary
Techniques are described for inter-domain segment routing using transport endpoint segments. A transport endpoint segment provisioned on a router within a domain represents any intra-domain tunnel originated at the router and having reachability to an indicated endpoint within the same domain. The provisioning router advertises a transport endpoint segment identifier (TESID) for the transport endpoint segment to other routers or a controller for use in segment routing. The TESID for the transport endpoint segment remains constant regardless of which intra-domain tunnel is bound to the transport endpoint segment. The provisioning router dynamically binds the transport endpoint segment to at least one intra-domain tunnel, and any changes to the bound intra-domain tunnel are updated locally at the provisioning router. In this way, an inter-domain segment routing tunnel may be constructed as a list TESIDs that are not affected by intra-domain tunnel changes.