Service Function Chain Tag Mapping via Metadata Segmentation
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Solution Overview
Problem
Current service chaining solutions, particularly in mobile networks, face scalability issues due to the limitations of fixed-size Service Function Path ID fields in headers, leading to inefficient forwarding rule configurations and increased lookup times, especially during mobility events.
Innovation Solution
The method involves embedding multiple tags in a Service Function Chain (SFC) Encapsulation header, using a metadata field to carry variable-length tag information, allowing for the generation and replacement of Service Chain Path IDs based on predefined rules, enabling efficient forwarding across service chains without requiring changes to existing SFC encapsulation proposals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flow rules are installed in network forwarding elements for each packet flow, then service chaining can be implemented, but the number of states in forwarding elements increases and lookup time increases
Solution Approach 1:
The patent segments the service chain identification into two parts: a compact service chain ID (SC-ID) for forwarding element lookup and detailed tag information stored in a metadata field. This segmentation allows forwarding elements to use only the compact SC-ID for routing decisions, reducing the number of states they need to maintain while still supporting service chaining functionality.
Solution Approach 2:
The patent introduces a metadata field as an intermediary between the compact SC-ID and the detailed tag information. The metadata field carries additional tag information without requiring forwarding elements to store and process all possible flow rules, thus reducing forwarding element complexity while maintaining service chaining capability.
2Adaptability or versatility
If flow rules are installed in network forwarding elements for each packet flow, then service chaining can be implemented, but lookup time increases
Solution Approach 1:
The patent segments the service chain identification into a compact SC-ID portion and detailed tag information. The compact SC-ID is used for rapid lookup in forwarding elements, while detailed tags are stored in the metadata field. This segmentation enables faster forwarding decisions by reducing the amount of information that needs to be processed during lookup.
3Ease of operation
If fixed-size Service Function Path ID fields are used in SFC encapsulation headers, then forwarding is simplified, but scalability is limited during mobility events
Solution Approach 1:
The patent introduces a metadata field that can dynamically carry variable-length tag information alongside the fixed-size SC-ID. This dynamic extension allows the system to scale during mobility events by accommodating additional tag information without changing the fundamental fixed-size structure that enables simple forwarding.
Solution Approach 2:
The patent adds another dimension to the service chain identification by introducing the metadata field as a supplementary structure. The fixed-size SC-ID handles the primary forwarding function, while the variable-length metadata field provides additional scalability for mobility events, effectively adding a second dimension to the identification system.
Data Source
AI summary
A method performed by a network node includes the network node receiving, from a first portion of a service chain, a packet having a header portion that includes a first service chain path ID and a metadata field. The method further includes the network node retrieving, according to one or more predefined rules, one or more tags included in the metadata field. The method further includes the network node generating a second service chain path ID based on the one or more retrieved tags. The method further includes the network node replacing the first service chain path ID by inserting the second service chain path ID in the header portion, where the packet is forwarded, to a second portion of the service chain, in accordance with the second service chain path ID.