VPLS Active-Active Multi-Homing via Dynamic Role Assignment
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Solution Overview
Problem
Existing VPLS networks are limited to active-standby multi-homing, which creates forwarding issues and restricts the ability to achieve active-active multi-homing, leading to inefficiencies in frame forwarding and address learning across interconnected VPLS nodes.
Innovation Solution
The implementation of a VPLS network with three or more interconnected nodes that are actively communicatively coupled to an external node, using Multiprotocol Label Switching (MPLS) packets with label stacks that include pseudowire or point-to-multipoint labels to prevent frame looping and flooding, while performing address learning and forwarding table convergence, enabling active-active multi-homing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active-standby multi-homing is implemented in VPLS networks, then redundancy is provided, but forwarding efficiency is reduced and active-active multi-homing is restricted
Solution Approach 1:
The patent implements dynamic role assignment where VPLS nodes can transition between active and standby roles based on traffic conditions and node availability. The load assignment module dynamically adjusts which nodes handle traffic for different customer devices, enabling flexible active-active multi-homing while maintaining redundancy. This resolves the contradiction by making the system adaptable rather than static.
Solution Approach 2:
The patent segments the VPLS network into multiple independently operable nodes that can simultaneously handle traffic. By dividing the network functionality across multiple nodes with distinct roles (active/standby) that can be dynamically reassigned, the system achieves both redundancy and forwarding efficiency. Each node can independently forward frames, eliminating the bottleneck of single-active architectures.
2Productivity
If multiple VPLS nodes are actively coupled to the same external node, then active-active multi-homing is enabled, but frame looping and flooding issues arise
Solution Approach 1:
The patent implements a feedback mechanism where VPLS nodes monitor traffic patterns and node states to dynamically adjust forwarding decisions. The load assignment module receives feedback about which nodes are actively handling traffic and uses this information to prevent duplicate frame forwarding and looping. This feedback loop enables active-active multi-homing while automatically preventing the harmful effects of frame duplication.
Solution Approach 2:
The patent introduces a control plane intermediary that mediates between multiple active VPLS nodes and the data plane forwarding operations. This intermediary coordinates the activity of multiple nodes, ensuring that frames are forwarded efficiently without causing loops or flooding. The intermediary manages the complex interactions between actively coupled nodes, enabling them to work together harmoniously.
3Reliability
If address learning is performed across multiple actively coupled VPLS nodes, then forwarding table convergence is achieved, but address learning conflicts occur
Solution Approach 1:
The patent changes the parameters of address learning by introducing node-specific identifiers and role-based learning rules. Instead of uniform address learning across all nodes, the system modifies the learning parameters based on node roles (active/standby) and assigns unique identifiers to distinguish learning entries from different nodes. This parameter modification enables forwarding table convergence while preventing conflicts by making learning entries distinguishable and non-conflicting.
Data Source
AI summary
In one embodiment, single-homing and active-active multi-homing is provided in a Virtual Private LAN Service (VPLS). A customer edge node actively communicates frames of a same Virtual Private Network (VPN) instance with two or more VPLS nodes of a VPLS network. The VPLS nodes are configured to appropriately forward frames throughout the VPLS network: without looping of a frame sent by the same external node back to the same external node, without flooding multiple copies of a frame to the same external node, and while performing learning of addresses in forwarding tables of said VPLS nodes such that said forwarding tables of said VPLS nodes converge despite frames of the same LAN service being received by said at least two of said VPLS nodes from the same external node.