Implicit Session Routing in Service Chains
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Solution Overview
Problem
Existing service chain architectures fail to effectively manage session state in service routers, particularly in scenarios involving addition, removal, or failure of appliances and service routers, due to the lack of mechanisms for implicit session routing and centralized signaling overload.
Innovation Solution
Implementing a decentralized system that uses mechanical load balancing to route sessions through a service chain, where virtual routing functions (VRFs) and service routing functions (SRFs) record and maintain previous and next hop information for each session, allowing for implicit session management without explicit signaling, and caching load-balancing decisions in session-routing tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centralized signaling mechanisms are used to manage session state in service routers, then session routing control is centralized and coordinated, but signaling overhead increases and system complexity increases
Solution Approach 1:
Each service router independently manages its own session state information using local VRF/SRF data structures. The routers autonomously determine appliance selection through load balancing functions without requiring centralized signaling or coordination, thereby eliminating signaling overhead while maintaining reliable session state management locally
Solution Approach 2:
The patent extracts the session state management function from a potential centralized controller and distributes it to individual service routers. Each router maintains its own session routing information independently, removing the need for centralized signaling mechanisms while preserving session management capabilities
2Reliability
If explicit signaling mechanisms are implemented for session routing, then session state can be managed across service zones, but signaling overhead increases
Solution Approach 1:
Service routers autonomously manage session state using local VRF/SRF structures without requiring explicit signaling between zones. Each router independently makes appliance selection decisions based on load balancing functions applied to local session information, eliminating the need for energy-consuming explicit signaling messages while maintaining session state coherence
Solution Approach 2:
The patent replaces the mechanical signaling system with a decentralized computational approach. Instead of exchanging signaling messages to manage session state, routers use local load balancing functions and cached session information to autonomously determine routing decisions, substituting communication overhead with local computational processing
3Stability of the object's composition
If session state is managed centrally, then coordination between service zones is improved, but system complexity and single point of failure increase
Solution Approach 1:
The patent segments session state management into independent local units at each service router. Each router maintains its own VRF/SRF session information separately without a centralized repository, distributing the management function across multiple independent nodes. This segmentation eliminates single points of failure while maintaining coordination through consistent load balancing logic applied independently at each router
Solution Approach 2:
Instead of centralizing session state management in a single controller, the patent inverts the architecture by distributing management capabilities to individual service routers. Each router independently manages session state locally rather than reporting to a central authority, thereby reducing system complexity and eliminating single points of failure while maintaining coordination through consistent decentralized decision-making
4Reliability
If mechanical load balancing is applied at each service zone, then session routing becomes decentralized and resilient, but routing decision complexity increases
Solution Approach 1:
The patent applies load balancing functions that operate on session state parameters stored in VRF/SRF data structures. By changing the state parameters (such as appliance selection based on load conditions) through standardized load balancing logic, the system achieves decentralized resilient routing while keeping the decision complexity manageable through parameter-based control rather than complex rule-based logic
Data Source
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AI summary
An example method is provided in one example embodiment and includes receiving a packet of a session from a previous hop router at a service zone of a service chain; recording the previous hop router for the session; determining an appliance to service the packet in the service zone using load balancing; recording an appliance identity for servicing the session in the service zone; determining a next hop router in the service chain for the packet using load balancing; and recording the next hop router for the session.