Asymmetric Routing Minimization via Flow Table Tunnel Mapping
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Solution Overview
Problem
Asymmetric routing in networks leads to scalability issues, particularly for large routers, as they need to independently select routes for both outbound and inbound traffic flows, requiring significant intelligence and increasing complexity.
Innovation Solution
Implementing a method where network nodes maintain a flow table to record packet flows and corresponding tunnels, with one node acting as a selector and the other as a follower, allowing the follower node to transmit packets through tunnels selected by the selector without needing to independently choose paths, thus reducing the need for intelligence at each node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If each router independently selects routes for both outbound and inbound traffic flows, then routing flexibility is improved, but device complexity and scaling capability deteriorate
Solution Approach 1:
The patent applies asymmetry by designating one router as the 'selector' that independently chooses tunnels for packet flows, while the other router becomes the 'follower' that automatically uses the same tunnels in reverse direction. This asymmetric role assignment eliminates the need for both routers to have independent routing intelligence, reducing complexity while maintaining routing flexibility through the selector's decisions.
Solution Approach 2:
The patent introduces tunnel identifiers as an intermediary mechanism that carries routing information between selector and follower routers. Instead of requiring the follower to independently make routing decisions, the tunnel identifier acts as a mediator that encodes the path information, allowing the follower to simply look up and use the pre-determined tunnel for returning traffic.
2Adaptability or versatility
If routers require independent route selection intelligence, then routing adaptability is improved, but scalability deteriorates
Solution Approach 1:
By creating asymmetric router roles where only the selector needs routing intelligence and the follower automatically mirrors the selector's tunnel choices, the system maintains routing adaptability through the selector while enabling network scaling by eliminating the intelligence burden from followers. This allows the network to scale to more routers without proportionally increasing total routing intelligence requirements.
Data Source
AI summary
In some examples, an example method to minimize asymmetric routing at a network node may include maintaining a flow table including one or more records, each record indicating a packet flow and a corresponding tunnel, receiving a data packet to process at a network node, and determining whether to process the data packet as a follower node. The method may also include, responsive to a determination to process the data packet as a follower node, determining whether there is an entry in the flow table for a packet flow associated with the received packet, and, responsive to a determination that there is an entry in the flow table for the packet flow, transmitting the received data packet through a tunnel corresponding to the packet flow.