CALR Rules for Link Aggregation Contraction Loss
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Solution Overview
Problem
Networks experience contraction loss due to congestion-related packet drops when a subset of network links fail, leading to inefficient bandwidth usage and potential network disconnection.
Innovation Solution
A system that dynamically generates Capacity Aware Local Repair (CALR) rules using topology and traffic matrix data to proactively set network links to inactive states when bandwidth falls below a threshold, rerouting traffic to backup links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If network links are grouped into a LAG to simplify configuration and improve routing, then configuration simplicity and routing efficiency are improved, but contraction loss occurs when links fail causing congestion-related packet drops
Solution Approach 1:
The system performs preliminary simulation of link failures and contraction scenarios before they occur in production. By pre-calculating down loss values and contraction loss values through traffic matrix simulations, the system determines appropriate CALR rules and contracted bandwidth thresholds in advance, enabling proactive protection against contraction loss when links actually fail
Solution Approach 2:
The system continuously monitors actual network bandwidth utilization and compares it against the contracted bandwidth threshold defined in the CALR rule. When the active bandwidth falls below the threshold, the system triggers a feedback action to deactivate the LAG, preventing contraction loss. This closed-loop feedback mechanism dynamically adapts to changing network conditions
2Reliability
If the LAG continues operation with reduced capacity after link failure, then network availability is maintained, but congestion-related packet drops increase
Solution Approach 1:
The system dynamically changes the operational state parameter of the LAG based on bandwidth threshold violations. When monitoring detects that active bandwidth falls below the contracted bandwidth threshold, the system changes the LAG state from active to inactive, transforming the parameter to prevent congestion-related packet drops while maintaining overall network availability through backup paths
3Reliability
If preconfigured backup paths are available to handle contracted traffic, then contraction loss can be avoided by deactivating the LAG, but network complexity increases
Solution Approach 1:
The system enables network devices to autonomously monitor their own LAG bandwidth utilization and automatically trigger deactivation when thresholds are violated, without requiring complex external control systems. The CALR rules are self-configured based on simulated traffic scenarios, and the devices self-manage the activation/deactivation decisions based on real-time monitoring, reducing overall system complexity
Data Source
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AI summary
A computerized method reduces contraction loss in a network using dynamically generated rules. Topology and traffic matrix data of a network are obtained, wherein the obtained data includes data associated with a network link of the network. A first traffic scenario is simulated to determine a down loss value of the network link, and a second traffic scenario is simulated to determine a contraction loss value of the network link. A capacity aware local repair (CALR) rule of the network link is generated using the determined down loss value and the determined contraction loss value, wherein the CALR rule includes a contracted bandwidth threshold. The generated CALR rule is provided to a network device associated with the network link, wherein the network device is enabled to set the network link to inactive based on bandwidth of the network link falling below the contracted bandwidth threshold of the generated CALR rule.