Server-Layer Path Negotiation with Iterative Constraint Relaxation
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Solution Overview
Problem
Communications networks face challenges in reliably forwarding packets when network topology changes, particularly in establishing and maintaining server-layer paths that meet specific latency, bandwidth, and cost requirements, especially during failures, without over-engineering the network and introducing high latency or shared risk link group constraints.
Innovation Solution
The client-layer network negotiates with the server-layer network to establish and replace server-layer paths by iteratively relaxing constraints such as latency, bandwidth, and Shared Risk Link Group (SRLG) requirements, using existing router interfaces and dense wavelength division multiplexing (DWDM) transponders, allowing for reduced-cost optical network restoration without additional equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network uses strict server-layer path constraints (latency, bandwidth, SRLG) to ensure communication reliability, then packet forwarding reliability is improved, but path establishment fails more often when topology changes occur
Solution Approach 1:
The patent implements dynamic constraint relaxation where the client-layer network iteratively adjusts server-layer path constraints (latency, bandwidth, SRLG) based on network topology changes and availability. The system transitions from static strict constraints to dynamic adaptive constraints, allowing path establishment to succeed under varying network conditions while maintaining reliability through iterative negotiation between client and server layers.
2Reliability
If the network over-engineers server-layer paths to handle failures, then communication reliability during failures is improved, but network cost and complexity increase
Solution Approach 1:
The patent changes the parameter of constraint strictness dynamically. Instead of over-engineering the network with redundant paths, the system adjusts path selection criteria (latency thresholds, bandwidth requirements, SRLG constraints) based on actual network conditions and failure scenarios. This allows the network to achieve failure recovery reliability through intelligent parameter adaptation rather than excessive infrastructure provisioning.
3Adaptability or versatility
If the network uses iterative constraint relaxation to establish paths, then path establishment success rate is improved, but negotiation time and latency increase
Solution Approach 1:
The patent applies preliminary action by pre-establishing multiple potential paths with varying constraint levels before actual communication occurs. The server-layer network pre-computes and prepares alternative paths that satisfy different constraint combinations, so when a path establishment request arrives, the system can quickly select from pre-prepared options rather than performing iterative negotiation in real-time, thus reducing negotiation time while maintaining high success rates.
Data Source
AI summary
In one embodiment, negotiation is performed between the client-layer (e.g., Layer-3 or Layer-2) network and the server-layer (e.g., optical) network to establish a path through the server-layer network with desired server-layer characteristics. This negotiation may include a first iteration of a client-layer request of one or more first server-layer characteristics followed by a negative server-layer response, and a subsequent iteration of a particular client-layer request of one or more particular server-layer characteristics followed by a positive server-layer response, with said particular server-layer characteristics including at least one relaxed server-layer characteristic of said first server-layer characteristics. One embodiment establishes, in response a client-layer request to the server-layer network responsive to the positive server-layer response, a server-layer path between said two client-layer devices that satisfies said particular server-layer characteristics, but does not satisfy said first server-layer characteristics.