EVPN Multicast Forwarding with Backup PE Tunnels

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Solution Overview

Problem

Current multicast networks face inefficiencies in content delivery when an ingress provider edge device is unaware of the correct provider edge device to connect with for receiving multicast content, leading to data loss and network flooding due to incorrect forwarding paths.

Innovation Solution

Establishing reverse path forwarding tunnels and unicast tunnels between ingress and egress provider edge devices within an EVPN instance, using Virtual Routing and Forwarding (VRF) extended community information to ensure correct multicast content delivery, and designating backup provider edge devices to temporarily forward content when the egress device stops receiving from the source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If current bridging strategies are used to ensure subscriber receives multicast content when connected to a provider edge device not receiving content from source, then subscriber availability is improved, but network flooding and inefficiency occur

Engineering Contradiction:

Improvesubscriber availabilityVSAvoidnetwork flooding

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent establishes reverse path forwarding tunnels and unicast tunnels between provider edge devices in advance, before content delivery issues occur. This preliminary setup of forwarding paths allows the network to efficiently redirect multicast content without causing flooding when a provider edge device fails to receive content from the source.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces designated provider edge devices as intermediaries that receive multicast content from sources and forward it through established tunnels to ingress provider edge devices. This intermediary approach replaces inefficient bridging strategies with structured tunneling through selected intermediate devices, preventing network flooding while ensuring content delivery.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If ingress provider edge device is unaware of correct egress provider edge device location, then network flexibility is improved, but data loss occurs due to incorrect forwarding paths

Engineering Contradiction:

Improvenetwork flexibilityVSAvoiddata loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent implements feedback mechanisms where egress provider edge devices send content announcements to ingress provider edge devices through established unicast tunnels. This feedback loop allows ingress devices to learn the correct location of content sources and adjust forwarding paths accordingly, preventing data loss while maintaining network flexibility.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent pre-establishes unicast tunnels between ingress and egress provider edge devices before content delivery begins. This preliminary action ensures that when ingress devices need to locate content sources, pre-configured communication paths are already in place, enabling reliable information exchange without data loss.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If backup provider edge devices are designated to temporarily forward content, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvecontent delivery continuityVSAvoidforwarding path management

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent designates backup provider edge devices and establishes their forwarding capabilities in advance, before failures occur. This preliminary designation includes pre-configuring unicast tunnels and forwarding rules, so when the primary egress device fails, backup devices can immediately take over without complex runtime decision-making, reducing operational complexity while maintaining reliability.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12549401B2Optimal multicast forwarding for sources behind EVPN fabric

Publication Date: 2026.02.10 CISCO TECHNOLOGY INC

AI summary

A system and associated methods provide procedures for establishing multicast connections and forwarding multicast content from a source to a subscriber when an ingress provider edge in communication with the subscriber is connected to an egress provider edge device belonging to an EVPN instance, especially in cases where the egress provider edge device is not receiving content from the source. The system configures “backup” provider edge devices belonging to the EVPN instance to temporarily forward the multicast content to the egress provider edge device on behalf of the source, enabling the ingress provider edge device and subscriber to continue to receive the multicast content from the source while the multicast network adjusts to recognize a new egress provider edge device. Methods of establishing connections between the ingress provider edge device and the correct egress provider edge device are also provided to avoid flooding and inefficient content forwarding throughout the network.