Backup Router Election for Multicast Traffic Recovery
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Solution Overview
Problem
In network environments, the failure of a Designated Router (DR) in a subnetwork leads to delays in detecting and recovering from the failure, resulting in packet loss due to the time taken for a new DR to be elected and multicast traffic to be rerouted, which is exacerbated in complex networking scenarios.
Innovation Solution
A method for electing a Backup Designated Router (BDR) based on predetermined rules, such as prioritizing PIM equipment by IP address, to rapidly recover multicast traffic forwarding when a DR fails, and ensuring seamless switching without packet loss, even when new PIM equipment joins the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new DR is elected after DR failure using conventional PIM protocol, then the network can recover from failure, but packet loss occurs during the election process due to delays in detection and rerouting
Solution Approach 1:
The patent pre-positions a Backup Designated Router (BDR) in standby mode before failure occurs. The BDR maintains synchronization with the DR and can immediately take over when failure is detected, eliminating the need for a full reelection process. This preliminary preparation of backup infrastructure directly reduces the recovery time and prevents packet loss during failover.
Solution Approach 2:
The patent introduces a BDR as an intermediary component between the DR and other network devices. The BDR acts as a mediator that can assume the DR's role during failure, maintaining communication flows and preventing direct disruption between the DR and network participants. This intermediary buffer smooths the transition during failover.
2Adaptability or versatility
If BDR equipment switching is performed when new PIM equipment joins the network, then the network adapts to new topology, but unnecessary BDR switching occurs that degrades network performance
Solution Approach 1:
The patent implements a mechanism where the BDR election and activation is triggered only by actual DR failure conditions, not by routine network changes. The system continuously monitors for genuine failure events and provides feedback to activate the BDR only when necessary. This feedback-controlled approach prevents spurious activations due to normal topology changes while still responding appropriately to actual failures.
Solution Approach 2:
The patent creates a dynamic BDR system that adapts its state based on actual network conditions. The BDR remains in a low-resource standby mode during normal operation and only becomes active when failure is detected. This dynamic state transition allows the network to maintain adaptability while minimizing performance degradation from unnecessary switching operations.
Data Source
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AI summary
Backup Designated Router (BDR) election and Designated Router (DR) failure processing methods and equipment are provided. When a user joins, a BDR in a subnetwork completes a preparation for forwarding multicast traffic for the user, but does not forward the multicast traffic through an interface; and when detecting that a DR in the subnetwork fails, the BDR is immediately switched to be a DR in the subnetwork, and forwards the multicast traffic for the user through the interface.