Inter-VRF Route Leaking via Border Leaf Nodes

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Solution Overview

Problem

Conventional systems face scalability limitations and sub-optimal forwarding paths when implementing inter-VRF route leaking, as they require configuring VRFs on all leaf nodes, leading to resource inefficiencies and increased routing hops.

Innovation Solution

The solution enables inter-VRF route leaking with optimized forwarding paths by configuring VRFs only on necessary leaf nodes, eliminating the need for additional VRF creation and allowing direct traffic forwarding between end hosts, independent of the fabric overlay, using a Dynamic Fabric Automation (DFA) architecture with MP-BGP and VXLAN/FabricPath technologies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If VRFs are configured on all leaf nodes to enable inter-VRF route leaking, then communication between VRFs is achieved, but device complexity and resource utilization deteriorate

Engineering Contradiction:

Improveinter-VRF communication capabilityVSAvoidVRF configuration complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces a border leaf node as an intermediary device that performs route leaking between VRFs. Instead of configuring VRFs on all leaf nodes, the border leaf node acts as a mediator that receives routes from one VRF and leaks them into another VRF. This centralized approach at the border leaf reduces the complexity of VRF configurations across the entire network while maintaining inter-VRF communication capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If VRFs are configured on all leaf nodes for route leaking, then routing isolation is maintained, but forwarding path optimality deteriorates

Engineering Contradiction:

Improverouting isolationVSAvoidforwarding path efficiency

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent segments the network into two functional parts: leaf nodes that maintain routing isolation for local VRFs, and border leaf nodes that handle inter-VRF route leaking. This segmentation allows most leaf nodes to maintain simple, isolated routing tables for their local VRFs, while only the border leaf nodes contain the additional routing information needed for inter-VRF communication. This reduces the forwarding path complexity and improves forwarding efficiency.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If additional VRFs are created for route leaking, then inter-VRF communication is enabled, but resource utilization deteriorates

Engineering Contradiction:

Improveroute leaking functionalityVSAvoidVRF instance quantity

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The border leaf node is designed to perform multiple functions: it acts as a regular leaf node for local VRF routing, serves as a route leaking point for inter-VRF communication, and functions as a border router for external network connectivity. By making the border leaf node multi-functional, the patent eliminates the need to create additional dedicated VRF instances solely for route leaking, thereby reducing the total quantity of VRF instances while maintaining full route leaking functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3219057B1Optimized inter-VRF (virtual routing and forwarding ) route leaking in network overlay based environments

Publication Date: 2022.07.06 CISCO TECHNOLOGY INC

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AI summary

In one embodiment, a method includes importing a route target for a remote Virtual Routing and Forwarding instance (VRF) at a leaf node in an overlay network, the leaf node comprising at least one local VRF configured thereon, processing routes received for the route target at the leaf node, and installing the routes for the remote VRF at the local VRF at the leaf node to enable inter- VRF communication via the leaf node. An apparatus and logic are also disclosed herein.