Data Plane Learning for Bidirectional Service Chains
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Solution Overview
Problem
Current service chain technologies tightly couple service chain structure and forwarding state, requiring a centralized controller to manage stateful and non-stateful service functions, which increases complexity and state information maintenance, and limits dynamic bidirectional service chain construction and redundancy.
Innovation Solution
Decoupling service chain structure from underlying network forwarding state by using a network service header (NSH) that includes path, location, and opaque metadata, allowing data plane learning and distributed ([service-id]-to-[location]) mappings, enabling each network node to determine and update stateful service functions and create reverse paths dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a centralized controller is used to manage service chain structure and forwarding state, then service chain management is simplified and controlled, but system complexity increases and state information maintenance burden grows
Solution Approach 1:
The patent extracts the forwarding state information from the centralized controller and places it directly in the packet headers (service path headers). This allows network nodes to make forwarding decisions independently based on header information, eliminating the need for complex centralized state management while maintaining controlled service chain operations
Solution Approach 2:
Network nodes perform self-service by using the service path headers embedded in packets to autonomously determine forwarding decisions. Each node reads the header information and forwards packets according to the specified service chain path without requiring centralized controller intervention for each forwarding decision
2Adaptability or versatility
If service chain structure is tightly coupled with forwarding state, then forwarding decisions can be made centrally, but dynamic bidirectional service chain construction is limited and redundancy is reduced
Solution Approach 1:
The patent segments the service chain information into discrete service path headers that can be independently manipulated. Each header contains specific forwarding instructions that can be dynamically modified to create flexible bidirectional service chains without affecting the overall structure stability
Solution Approach 2:
The service path headers enable dynamic service chain construction by allowing forwarding paths to be changed on-the-fly based on packet characteristics and network conditions. Bidirectional service chains can be dynamically created and modified while maintaining structural integrity through the header-based control mechanism
3Reliability
If centralized controller manages all state information, then service chain policies can be enforced uniformly, but state information maintenance burden and processing overhead increase
Solution Approach 1:
The service chain forwarding information is prepared in advance and embedded in the service path headers before packets enter the network. This preliminary action allows network nodes to enforce service chain policies reliably by simply reading the pre-configured header information, without requiring real-time centralized processing
Solution Approach 2:
The patent replaces the mechanical centralized control system with an information-based system where service path headers carry all necessary forwarding instructions. This substitution eliminates the need for continuous centralized state management and processing overhead, improving packet forwarding efficiency while maintaining policy enforcement reliability
Data Source
AI summary
Techniques are provided to decouple service chain structure from the underlying network forwarding state and allow for data plane learning of service chain forwarding requirements and any association between services function state requirements and the forward and reverse forwarding paths for a service chain. In a network comprising a plurality of network nodes each configured to apply a service function to traffic that passes through the respective network node, a packet is received at a network node. When the network node determines that the service function it applies is stateful, it updates context information in a network service header of the packet to indicate that the service function applied at the network node is stateful and that traffic for a reverse path matching the classification criteria is to be returned to the network node.