LSP Stitching Without Inter-Domain RSVP-TE Sessions
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Solution Overview
Problem
Current methods for establishing end-to-end Label Switched Paths (LSPs) across multiple domains require running a Resource Reservation Protocol-Traffic Engineering (RSVP-TE) session over inter-domain links, increasing complexity and cost in network operations.
Innovation Solution
The method involves creating and stitching LSP tunnel segments across multiple autonomous system (AS) or area domains without running an RSVP-TE session, using Explicit Route Objects (EROs), next-hop node labels, and cross-connects managed by border nodes and Path Computation Elements (PCEs, with stitching and nesting labels enabling seamless path creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RSVP-TE session is run over inter-domain links to establish end-to-end LSP across multiple domains, then reliable LSP establishment is achieved, but device complexity and operational complexity increase
Solution Approach 1:
The patent divides the end-to-end LSP establishment process into separate domain-specific LSP segments. Each domain establishes its own LSP segment independently using local RSVP-TE sessions, rather than running a single RSVP-TE session across all inter-domain links. The border nodes then stitch these segments together using label swapping, achieving reliable end-to-end LSP establishment while limiting RSVP-TE complexity to individual domains only.
2Reliability
If RSVP-TE session is run over inter-domain links, then end-to-end LSP can be established, but cost of network operations increases
Solution Approach 1:
The patent segments the LSP establishment into domain-specific operations, allowing each domain to manage its own LSP segment independently. This reduces the scope of RSVP-TE sessions to local domains rather than requiring them across all inter-domain links, thereby reducing operational costs while maintaining end-to-end LSP functionality through border node stitching.
Solution Approach 2:
Border nodes act as intermediaries that stitch together LSP segments from different domains. These border nodes perform label swapping to connect segments without requiring RSVP-TE sessions across inter-domain links, reducing operational complexity and cost while maintaining end-to-end connectivity.
3Ease of operation
If LSP segments are stitched without session crossing domains, then operational complexity is reduced, but coordination between domains becomes more challenging
Solution Approach 1:
Border nodes serve as intermediaries that facilitate coordination between domains by performing label swapping operations. They receive LSP segments from one domain, apply appropriate label transformations, and forward them to the next domain. This intermediary function simplifies coordination by localizing the complexity to border nodes rather than requiring complex inter-domain session management.
Solution Approach 2:
Each domain independently establishes its own LSP segment using local RSVP-TE sessions and local path computation, making domain-specific decisions without requiring complex inter-domain coordination. The domains essentially serve themselves by establishing local segments, while border nodes handle the stitching, thereby reducing overall coordination complexity.
Data Source
AI summary
Methods and apparatus are provided for stitching and/or nesting label-switched path (LSP) segments for creating an end-to-end (E2E) LSP without running a Resource Reservation Protocol-Traffic Engineering (RSVP-TE) session over an inter-domain link. The present disclosure is applicable to various types of domains including, but not limited to, autonomous system (AS) domains and area domains. Advantages of the disclosed embodiments include providing an easy and efficient method for creating E2E LSP, simplifying network operations, and reducing the cost of network Operations, Administration, and Maintenance (OAM).