Scaled AIGP Attributes for Multi-Domain IGP Path Selection
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Solution Overview
Problem
Existing Interior Gateway Protocol (IGP) systems face challenges in integrating non-uniform IGP domains due to differences in metric scales across Autonomous Systems, leading to inaccurate path selection and loss of link state information when using protocols like BGP.
Innovation Solution
The implementation of a scaled Accumulated Interior Gateway Protocol (AIGP) attribute that adjusts link metrics to conform to the metric scale of adjacent IGP domains, incorporating static metrics for non-IGP links, to provide a unified end-to-end view of network topology and improve path selection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If BGP is used to exchange routing information among Autonomous Systems, then routing reachability information is exchanged, but link state information such as cost metrics is lost
Solution Approach 1:
The patent introduces AIGP as an intermediary mechanism that bridges IGP and BGP protocols. The AIGP attribute acts as a mediator that carries IGP metric information through BGP routing updates, allowing link state information to be preserved and transmitted across Autonomous System boundaries without requiring modification of the core BGP protocol
Solution Approach 2:
The patent applies metric scaling transformations to adapt IGP cost metrics from one Autonomous System to another. By changing the parameter scale of cost metrics through mathematical transformations (scaling factors), the system enables meaningful comparison and path selection across domains with different metric configurations while preserving the original link state information
2Loss of information
If AIGP is used to carry IGP metrics across IGP domains, then link state information is preserved, but path selection accuracy deteriorates due to non-uniform deployment of IGP
Solution Approach 1:
The patent implements metric scaling that transforms cost metrics from different IGP domains into a unified scale. By applying domain-specific scaling factors to the AIGP attributes, the system normalizes metrics across non-uniform IGP deployments, enabling accurate end-to-end path cost calculation and restoration of path selection precision
Solution Approach 2:
The patent creates metric equipotentiality across Autonomous System boundaries by scaling all IGP domains to a common reference scale. This eliminates potential differences in metric interpretation between domains, allowing routers to make accurate path selection decisions based on consistent cost metrics throughout the multi-domain network
3Adaptability or versatility
If metric scaling is applied to conform link metrics to adjacent IGP domain scales, then unified end-to-end topology view is achieved, but device complexity increases
Solution Approach 1:
The patent implements metric scaling in advance at the Autonomous System Boundary Routers before routing information is propagated into the IGP domain. By pre-scaling the AIGP attributes and incorporating them into the IGP link state database beforehand, the system achieves unified topology views without requiring complex real-time calculations or modifications throughout the entire network
Solution Approach 2:
The patent enables IGP domains to self-adapt to different metric scales through autonomous scaling factor application. Each ASBR independently determines and applies its own scaling factor based on local domain characteristics, eliminating the need for centralized coordination or complex inter-domain negotiation mechanisms
Data Source
AI summary
In general, techniques are described by which to provide a scaled end-to-end view of link metrics to integrate multiple non-uniform Interior Gateway Protocol (“IGP”) domains. For example, an Accumulated Interior Gateway Protocol (“AIGP”) attribute, a non-transitive BGP attribute, which includes a link metric assigned to a link within a first IGP domain, is scaled to conform to a metric scale of the second IGP domain. The AIGP attribute may also add link metric assigned to a link within the second IGP domain and may add static metrics of non-IGP links connecting the IGP domains. An IGP domain may set its IGP to the scaled AIGP attribute such that the link metric may include a uniformly scaled end-to-end view of link metrics across the IGP domains. Additionally, a sham-link is assigned a metric value in accordance with the scaling techniques.