TRILL LAN Forwarder Assignment Minimization
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Solution Overview
Problem
Existing methods for appointing forwarders in TRILL LANs fail to consider existing appointments, leading to traffic disruption when changes occur, as they do not ensure equal load distribution among routing bridges.
Innovation Solution
A method that identifies trigger events such as node additions or removals, adjusts the number of VLANs assigned to each node to maintain equal distribution by transferring VLANs in contiguous chunks, minimizing disruption and ensuring each node has an equal load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If simple load-sharing logic is used to assign appointed forwarders (V/N distribution), then the appointment process is simple and fast, but traffic disruption occurs for a large number of VLANs due to frequent changes in appointed forwarder
Solution Approach 1:
The system performs preliminary assessment of the current appointed forwarder state before making any changes. When a trigger event occurs (node addition/removal), the system first identifies which nodes are currently appointed forwarders and which VLANs they serve, then plans the redistribution to minimize disruptions before executing the reassignment.
Solution Approach 2:
The patent applies different treatment to different nodes based on their current role. Nodes that are currently appointed forwarders are given priority retention of their VLAN assignments, while non-appointed nodes are assigned VLANs only after the existing appointed nodes have been considered. This local differentiation minimizes the number of VLANs that need to be moved.
2Productivity
If equal distribution of VLANs among nodes is enforced, then load balancing is improved, but the complexity of the appointment algorithm increases
Solution Approach 1:
The patent segments the VLAN assignment process into distinct phases: identification of trigger events, determination of current appointed forwarders, calculation of target distribution, and incremental reassignment. This segmentation allows the complex problem of equal distribution to be broken down into manageable steps that can be executed systematically.
Solution Approach 2:
The system dynamically adjusts the appointed forwarder assignments based on the current state of the network. Rather than using a static predetermined assignment, the algorithm adapts to trigger events (node additions/removals) and continuously strives for equal distribution while minimizing disruptions, making the system flexible and responsive to changing conditions.
Data Source
AI summary
A methodology is described for achieving efficient forwarder appointments. Such efficient appointment may provide an equal load on each participating routing bridge in the TRILL LAN. Load may be viewed as the number of VLANs for which a given node is an appointed forwarder. Furthermore, efficient appointment may be executed with a minimum of traffic disruption. Minimal disruption may be ensured by forwarder appointments by moving a minimum number of VLANs to ensure an equal load on each participating routing bridge.