SRv6 SFF Forwarding via End.PT.SID and Control Flag
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Solution Overview
Problem
The complexity and high overhead of Service Function Forwarders (SFFs) in forwarding packets within an SRv6 service function chain, due to the need to strip and restore Segment Routing Headers (SRHs).
Innovation Solution
The introduction of an endpoint penetrate segment ID (End.PT.SID) that allows the SFF to forward SRv6 packets to an SF device without stripping the SRH, and the use of a control flag to indicate the SF device to offset the SRH for service processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the SFF strips and restores the SRH in the SRv6 packet, then the SRv6 packet can be forwarded to SRv6-unaware SF devices, but the SFF implementation becomes complex and overhead increases
Solution Approach 1:
The patent extracts the SRH processing function from the SFF and transfers it to the SF device. The SFF simply forwards the SRH intact to the SF device, which then strips and restores the SRH during service processing. This extraction eliminates the complexity of SRH management in the SFF while maintaining compatibility with SRv6-unaware devices.
Solution Approach 2:
The SF device acts as an intermediary that handles SRH processing between the SFF and the service processing function. Instead of the SFF directly stripping and restoring SRH, the SF device mediates this process, simplifying the SFF's role to basic packet forwarding while enabling SRv6-unaware device compatibility.
2Productivity
If the SFF strips and restores the SRH for each packet, then service processing can be performed by SF devices, but the processing overhead and time consumption increase
Solution Approach 1:
The time-consuming SRH stripping and restoring operations are extracted from the SFF's processing path and performed by the SF device. This allows the SFF to forward packets more quickly without the overhead of SRH manipulation, while service processing capability is maintained through the SF device's SRH handling.
Solution Approach 2:
The SF device performs SRH stripping as a preliminary action before service processing and restores it after processing. This preliminary action separates the SRH management from the main forwarding path, reducing the time penalty in the critical forwarding path while maintaining complete service processing capability.
3Ease of operation
If the SFF maintains state information for SRH stripping and restoring, then packet forwarding can be performed, but the forwarding plane becomes stateful and complex
Solution Approach 1:
The state management requirements for SRH tracking are extracted from the SFF's forwarding plane and transferred to the SF device. The SFF becomes a stateless forwarder that simply passes SRH-containing packets to the SF device, which maintains the necessary state information for SRH stripping and restoring operations.
Solution Approach 2:
The SF device serves itself by maintaining the state information needed for SRH processing. Instead of the SFF needing to track and manage SRH state across multiple packets, the SF device independently manages its own SRH state, simplifying the forwarding plane to a stateless architecture.
Data Source
AI summary
This application provides a method for forwarding a packet in an SRv6 service function chain, an SFF, and an SF device, and belongs to the field of communication technologies. In this application, an End.PT.SID is used to identify that the SFF forwards an SRv6 packet to the SF device without stripping an SRH. Based on the End.PT.SID, the SFF does not strip the SRH in the SRv6 packet, but sends the SRv6 packet to the SF device. In addition, the SFF includes a control flag in the SRv6 packet, so that the control flag is used to identify a scenario in which an IPv6 extension header needs to be offset. The SF device directly offsets the IPv6 extension header in the SRv6 packet based on the control flag, to skip the SRH for service processing.