Active-Active Multi-Homing PE Router Link Aggregation
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Solution Overview
Problem
Traditional multi-homed deployments in virtual private local area networks (VPLS) typically utilize an 'active-standby' link topology, which is wasteful of resources as only a single link is used to handle network traffic at any given time and can lead to issues like packet duplicates and MAC moves.
Innovation Solution
Implementing an 'active-active' link topology by configuring all multi-homing PE routers to form a multi-chassis link aggregation group for both physical access links and pseudowires, allowing concurrent active operation and avoiding duplicate packets and data loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active-standby link topology is used in multi-homed deployments, then issues like packet duplicates and MAC moves are avoided, but network resources are wasted as only a single link handles traffic at any given time
Solution Approach 1:
The patent implements dynamic link activation where multiple PE routers can simultaneously act as active designated forwarders based on real-time link status and traffic conditions. This transforms the static active-standby model into a dynamic active-active model, allowing all links to participate in traffic forwarding while maintaining reliability through coordinated control.
Solution Approach 2:
The patent introduces a control mechanism that acts as an intermediary between multiple PE routers to coordinate their forwarding decisions. This control plane component manages the active-active state across routers, preventing packet duplicates and MAC moves while enabling full utilization of all physical links through intelligent traffic distribution.
2Productivity
If all PE routers operate as active designated forwarders concurrently, then network resources are fully utilized, but issues like packet duplicates and data loops may occur without proper coordination
Solution Approach 1:
The patent implements feedback mechanisms where PE routers exchange status information and forwarding decisions with the control plane. This feedback loop allows the system to monitor traffic flow, detect potential duplicates or loops, and dynamically adjust forwarding behavior to maintain network integrity while maximizing resource utilization.
Solution Approach 2:
The control plane acts as an intermediary that coordinates forwarding decisions among all active PE routers. It receives traffic information, determines optimal forwarding paths, and distributes commands to prevent packet duplicates and data loops, enabling all routers to operate actively without causing network issues.
3Device complexity
If traditional active-standby configuration is used, then system complexity is reduced with clear role assignment, but redundancy is insufficient as standby links remain idle
Solution Approach 1:
The patent makes all PE routers multi-functional by enabling each router to simultaneously serve as an active designated forwarder for different traffic flows or time periods. This universal active capability replaces the specialized active-standby roles, allowing any router to handle traffic on any link, thereby maximizing redundancy while maintaining manageable complexity through standardized behavior.
Data Source
AI summary
Techniques are described for forwarding packets in a VPLS using multi-homing PE routers configured in an “active-active” link topology. A router includes a control unit that forms a customer-facing multi-chassis link aggregation group (LAG) to include a plurality of active access links that couple the router and a second router to a multi-homed customer site associated with the VPLS domain. The control unit also forms a core-facing multi-chassis LAG within the VPLS domain to include a plurality of pseudowires that connect the router and other member routers of the core-facing LAG to a common remote router of the VPLS domain. The router receives layer two (L2) packets from the multi-homed customer site on one or more of the active access links and forwards the L2 packets to the remote router over one or more of the pseudowires using the core-facing multi-chassis LAG.