BIER-TE Scalability via Unicast MPLS-TE Underlay

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Solution Overview

Problem

Conventional BIER-TE architectures face scalability limitations due to the linear dependency on the length of the BitString, which restricts the size of the network and requires a SDN controller for path computation.

Innovation Solution

The proposed architecture combines BIER with stateful unicast MPLS-TE tunneling, using unicast MPLS-TE tunnels as an underlay for the BIER layer, allowing for scalable BIER-TE deployments without the need for a SDN controller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional BIER-TE architecture is used, then BIER multicast can be implemented, but scalability is limited due to linear dependency on BitString length

Engineering Contradiction:
ImprovescalabilityVSAvoidBitString length dependency
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces unicast MPLS-TE tunnels as an intermediary layer between the BIER control plane and the underlying network infrastructure. These tunnels act as mediators that carry BIER traffic along pre-computed optimal paths, decoupling the BIER forwarding logic from the actual path computation and enabling scalable deployment without SDN controllers.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the BIER-TE architecture into distinct functional layers: the BIER control plane for bitstring-based forwarding decisions, the MPLS-TE tunnel infrastructure for traffic engineering and path computation, and the underlying transport network. This segmentation allows each layer to operate independently, improving scalability and reducing complexity.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If conventional BIER-TE architecture is used, then multicast forwarding can be achieved, but path computation requires SDN controller

Engineering Contradiction:
Improvepath computationVSAvoidSDN controller dependency
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent enables routers to perform autonomous path computation for BIER traffic by leveraging the existing MPLS-TE tunnel infrastructure. Each router can independently compute optimal paths using locally available IGP information and pre-established MPLS-TE tunnels, eliminating the need for centralized SDN controller intervention in path computation operations.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent pre-establishes MPLS-TE tunnels between routers before BIER traffic needs to be forwarded. These tunnels are set up in advance using standard MPLS-TE procedures, so when BIER traffic arrives, the path computation is already complete and the forwarding path is ready, eliminating the need for real-time SDN controller involvement.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If BIER is implemented over traditional infrastructure, then multicast efficiency is improved, but traffic engineering capabilities are limited

Engineering Contradiction:
Improvemulticast efficiencyVSAvoidtraffic engineering
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent merges BIER multicast forwarding with MPLS-TE traffic engineering capabilities into a unified architecture. By overlaying BIER on top of MPLS-TE tunnels, the system combines the efficiency of stateless BIER forwarding with the flexible traffic engineering capabilities of MPLS-TE, enabling both multicast optimization and fine-grained path control simultaneously.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3731475B1Bier traffic engineering (bier-te) using unicast MPLS-te tunnels
Publication Date: 2025.04.23 NOKIA SOLUTIONS & NETWORKS OY
  • EP3731475B1 patent drawingFigure 1
  • EP3731475B1 patent drawingFigure 2
  • EP3731475B1 patent drawingFigure 3A

AI summary

At a router, at least one memory and computer program code stored therein are configured to, with at least one processor, cause the router to: determine source router identification information for a tunnel traversing the router based on a routable source IP address for the tunnel; determine destination router identification information for the tunnel based on a routable destination IP address for the tunnel; program a bit string entry for the tunnel in a Bit Index Forwarding Table (BIFT) for tunnels from a source router to a plurality of destination routers, the BIFT being indexed based on the source router identification information and at least a portion of the destination router identification information; and route packet data received at the router according to the BIFT.