HA Router Policy Transfer to Eliminate Redundant Packet Lookups

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Solution Overview

Problem

In SDWAN networks, redundant policy lookups are required when transferring packets between HA standby and active routers, leading to inefficient use of computing resources and increased processing time due to multiple NAT methods and application-specific requirements.

Innovation Solution

Perform a policy lookup at a first router and include the policy action in the packet header, allowing the second router to process the packet without performing an additional lookup, thereby optimizing packet handling in HA clusters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If policy lookup is performed at both standby router and active router, then packet processing can be completed, but computing resources are wasted and processing time increases

Engineering Contradiction:
Improvepacket processing completionVSAvoidcomputing resource efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The standby router performs the policy lookup action in advance before taking over traffic. When a packet arrives at the standby router, it looks up the policy action and attaches it to the packet header before forwarding to the active router. This preliminary action eliminates the need for the active router to perform another policy lookup, thus avoiding wasted computing resources while ensuring reliable packet processing.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If policy lookup is performed at both standby router and active router, then packet processing can be completed, but processing time increases

Engineering Contradiction:
Improvepacket processing completionVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The standby router performs the policy lookup action in advance before taking over traffic. When a packet arrives at the standby router, it looks up the policy action and attaches it to the packet header before forwarding to the active router. This preliminary action eliminates the need for the active router to perform another policy lookup, thus avoiding wasted computing resources while ensuring reliable packet processing.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If multiple policy lookups are performed in HA cluster, then application-specific NAT requirements are met, but computational overhead increases

Engineering Contradiction:
Improveapplication-specific NAT supportVSAvoidcomputational overhead
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The packet header acts as an intermediary carrier that transmits the policy action information from the standby router to the active router. By attaching the policy action to the packet header, the system enables application-specific NAT requirements to be met without requiring the active router to perform another policy lookup, thus reducing computational overhead while maintaining adaptability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The standby router performs the policy lookup action in advance before taking over traffic. When a packet arrives at the standby router, it looks up the policy action and attaches it to the packet header before forwarding to the active router. This preliminary action eliminates the need for the active router to perform another policy lookup, thus avoiding wasted computing resources while ensuring reliable packet processing.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4704397A1Efficient policy handling in high availability network
Publication Date: 2026.03.04 CISCO TECHNOLOGY INC
  • EP4704397A1 patent drawingFigure 1
  • EP4704397A1 patent drawingFigure 2
  • EP4704397A1 patent drawingFigure 3

AI summary

In one aspect, a method includes receiving, at a first router, a data packet from a network device via a communication channel, executing, by the first router, a policy lookup for the data packet to determine a policy action for handling the data packet, including, by the first router, the policy action in a header of the data packet, and transmitting, by the first router, the data packet to a second router where the second router processes the data packet based on the policy action included in the header of the data packet.