Routing Controller PCEP Extension for Multi-Domain Path Computation
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Solution Overview
Problem
Current multi-domain routing architectures in communications networks, such as those employing the Optical Interworking Forum (OIF) External Network-Network Interface (E-NNI) Routing, face limitations in intra-domain routing information dissemination and path computation, leading to suboptimal network resource utilization due to the reliance on minimum TE metric values, which results in high blocking probabilities and inefficient resource allocation.
Innovation Solution
A lightweight PCEP extension is introduced, incorporating a novel Lower Bound (LB) flag within the PCEP Metric Object, allowing for the computation and advertisement of multiple path metrics across domains, enabling abstraction schemes that improve blocking probability performance and stability without compromising the advertised service level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only minimum TE metric values are advertised for intra-domain links, then the routing information dissemination is simplified, but network resource utilization becomes suboptimal and blocking probability increases
Solution Approach 1:
The patent segments the path metric information into multiple tiers: minimum TE metric values for simplified routing decisions, and alternative path metric values for load balancing opportunities. This segmentation allows different levels of detail to be used in different contexts, resolving the contradiction between simplicity and resource utilization.
Solution Approach 2:
The patent introduces dynamic path selection by advertising multiple metric values (minimum and alternative) that enable load balancing across different paths. Instead of a static single-metric approach, the system dynamically selects paths based on current network conditions and load distribution requirements, improving resource utilization without significantly increasing complexity.
2Productivity
If multiple path metrics are computed and advertised across domains, then load balancing and resource utilization improve, but the complexity of path computation and information dissemination increases
Solution Approach 1:
The patent extracts only the necessary alternative path metric information from the complete path computation results, rather than advertising all possible path details. This extraction approach provides sufficient information for load balancing while avoiding the complexity of disseminating exhaustive path data.
Solution Approach 2:
The patent changes the parameter representation by advertising multiple metric values (minimum and alternative) for the same link rather than a single complex path description. This parameter change simplifies the information structure while enabling load balancing functionality.
3Ease of operation
If abstracted intra-domain routing information is disseminated to other domains, then inter-domain path computation is simplified, but blocking probability increases due to loss of detailed path information
Solution Approach 1:
The patent performs preliminary path computations within each domain to identify and advertise alternative path metrics before inter-domain path computation occurs. This preliminary action ensures that when abstracted routing information is exchanged between domains, the necessary load balancing options are already prepared, preventing blocking without requiring detailed end-to-end path information.
Data Source
AI summary
A system, method, and node for a Routing Controller (RC) to obtain from a Path Computation Element (PCE), network resource path metrics across a plurality of domains in a communication network in which each domain includes a plurality of Border Nodes (BNs). The RC sends to the PCE, a first message requesting a first path computation between each pair of BNs. The first message contains a maximum metric-value that a path computation must not exceed for a Path Computation Client (PCC) to consider the path computation acceptable. The RC then sends a second message requesting the PCE to compute a subsequent path computation for each BN pair for which the first path computation did not exceed the maximum metric-value. The second message contains a minimum metric-value that a path metric must exceed for the PCC to consider the path metric acceptable. The RC then receives the computed subsequent path computation.