EVPN Designated Forwarder Assignment for VLAN Load Balancing

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Solution Overview

Problem

The existing RFC 7432 mechanism for designated forwarder (DF) election in Ethernet Virtual Private Networks (EVPNs) can result in unbalanced distribution of Broadcast, Unknown-unicast, and Multicast (BUM) traffic load across Provider Edge (PE) devices, leading to decreased network performance and potential failures.

Innovation Solution

A modified DF election process that generates ordered lists of Provider Edge (PE) devices and Virtual Local Area Network (VLAN) identifiers, ensuring even distribution of BUM traffic by assigning PE devices as designated or non-designated forwarders based on ordinal positions and VLAN identifiers, thereby achieving load balancing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the existing RFH 7432 mechanism for designated forwarder election is used, then the DF election process is simple to implement, but the BUM traffic load distribution becomes unbalanced across PE devices

Engineering Contradiction:

ImproveDF election process simplicityVSAvoidBUM traffic load distribution balance

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent changes the parameter used for DF election from a simple priority-based selection to a hash-based selection using VLAN identifier and PE device identifier. This parameter transformation ensures that the DF selection is distributed evenly across multiple PE devices, achieving balanced BUM traffic load distribution while maintaining election process simplicity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a hash function as an intermediary transformation layer that copies and transforms the combination of VLAN identifier and PE device identifier into a distributed selection result. This copying mechanism through hashing ensures uniform distribution of DF assignments without complicating the underlying election logic

Inventive Principle:

Principle #26Copying

2Ease of manufacture

If the existing RFH 7432 mechanism is used, then the implementation is straightforward, but network performance decreases due to unbalanced traffic load

Engineering Contradiction:

ImproveDF election implementation easeVSAvoidnetwork performance

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

By transforming the DF selection parameter from simple priority to a hash-based value derived from VLAN and PE device identifiers, the patent achieves balanced traffic distribution that improves network performance while keeping the implementation straightforward through the use of standard hashing operations

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If the existing RFH 7432 mechanism is used, then the DF election process is simple, but potential network failures occur due to traffic concentration

Engineering Contradiction:

ImproveDF election process complexityVSAvoidnetwork stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent transforms the DF selection mechanism by using hash functions on VLAN and PE device identifiers, which distributes traffic load evenly across PE devices. This prevents traffic concentration that could cause network failures, improving reliability while adding minimal complexity to the election process

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a distributed DF selection mechanism where each PE device independently determines its DF status based on hash calculations. This feedback-based approach ensures that no single PE device becomes a bottleneck, enhancing network stability through automatic load distribution

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20260005965A1Methods for assigning provider devices as designated forwarders for different vlans

Publication Date: 2026.01.01 RUCKUS IP HOLDINGS LLC

AI summary

A method of forwarding traffic to a client edge (CE) device comprises using an ordered list of virtual local area network (VLAN) identifiers, where each VLAN identifier corresponds to a respective one of a plurality of VLANs, to assign, for each of the plurality of VLANs, one of a plurality of provider edge (PE) devices that are connected to the CE device to forward traffic that is within a class of traffic to the CE device.