SR App-Segment Integration with SFC Header Metadata
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Solution Overview
Problem
In segment routed networks, integrating segment routing (SR) with service function chaining (SFC) poses challenges as service functions are not configured to process extraneous information like SR forwarding labels, requiring complex reclassification and coordination between services and network configuration.
Innovation Solution
The solution involves inserting an indication of forwarding labels into the metadata of the SFC header, allowing SR information to be retained during and after packet processing by service functions, eliminating the need for complex reclassification and coordination by storing and retrieving the SR label stack using an app-segment ID or moving the entire label stack into metadata.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SR forwarding labels are processed through service functions, then service function chaining can be implemented, but service functions cannot process extraneous SR information requiring complex reclassification
Solution Approach 1:
The patent extracts SR forwarding labels from the packet header before service function processing and stores them separately in a label stack. This removes the extraneous SR information that service functions cannot process, while preserving it for post-processing restoration of the original SR path
Solution Approach 2:
The patent introduces an intermediary data structure (label stack) that temporarily holds SR forwarding labels during service function processing. This mediator allows the service functions to operate on simplified packets without SR labels while enabling restoration of SR routing information after service processing
2Ease of operation
If SR labels are removed before service processing, then service functions can process packets without extraneous information, but SR path information must be preserved for post-processing
Solution Approach 1:
The patent temporarily discards SR forwarding labels from the packet header before service function processing by moving them to a separate label stack. After service processing completes, the original SR labels are recovered and restored to enable continuation of SR routing. This approach simplifies service function operation while preserving necessary SR path information
Data Source
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AI summary
In one embodiment, a device in a network receives a packet that includes one or more forwarding labels and a service function chaining (SFC) header. The device removes the one or more forwarding labels from the packet. The device inserts an indication of the one or more forwarding labels into metadata of the SFC header. The device forwards the packet with the inserted indication of the one or more forwarding labels to a service function.