BIER Core Network Stitches PIM Access via Border Routers

Solution Overview

Problem

Existing multicast technologies face challenges in deploying Bit Indexed Explicit Replication (BIER) due to complexities in integration with Protocol Independent Multicast (PIM) networks, requiring stateful routers and explicit tree-building protocols, which limits scalability and flexibility.

Innovation Solution

The implementation of a multicast capability that supports BIER deployment within a network, allowing for the stitching of traditional PIM access networks via a BIER core network using PIM JOIN and PRUNE messages signaled across BIER tunnels, enabling a stateless and scalable multicast solution without the need for multicast states or Border Gateway Protocol (BGP).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional PIM multicast is used, then multicast functionality is provided, but router complexity and state maintenance requirements increase

Engineering Contradiction:

Improvemulticast functionalityVSAvoidrouter complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The network is segmented into a BIER core domain and PIM access domains. The core network uses stateless BIER forwarding while access networks use traditional PIM, dividing the complexity management across different network segments. Border routers act as transition points between the two domains.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Border routers serve as intermediaries between the BIER core domain and PIM access domains. These routers translate and adapt control messages (PIM JOIN/PRUNE) between the two different multicast paradigms, enabling seamless integration without requiring end-to-end PIM or pure BIER throughout the entire network.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If stateful multicast protocols are used, then multicast routing is achieved, but scalability and network efficiency deteriorate

Engineering Contradiction:

Improvemulticast routingVSAvoidnetwork efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The network is segmented into a BIER core domain and PIM access domains. The core network uses stateless BIER forwarding while access networks use traditional PIM, dividing the complexity management across different network segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The BIER core network performs automatic multicast packet replication and forwarding based on bitmasked destination addresses without requiring per-flow state maintenance. Each BIER router independently processes packets using the bitmask information carried in the packet header, eliminating the need for complex state synchronization across the core network.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If BIER is deployed in a full IGP area, then multicast coverage is maximized, but control message propagation complexity increases

Engineering Contradiction:

Improvemulticast coverageVSAvoidcontrol message propagation

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The network is segmented into a BIER core domain and PIM access domains. The core network uses stateless BIER forwarding while access networks use traditional PIM, dividing the complexity management across different network segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of requiring BIER deployment throughout the entire IGP area, the solution applies BIER selectively to the core network portion that benefits most from stateless forwarding. The access networks can continue using traditional PIM, performing partial deployment that achieves the desired efficiency improvements without the full complexity of universal BIER adoption.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11431650B2Multicast based on bit indexed explicit replication

Publication Date: 2022.08.30 NOKIA TECHNOLOGIES OY

AI summary

The present disclosure generally discloses a multicast capability configured to support multicast that is based on use of Bit Indexed Explicit Replication (BIER). The multicast capability may be configured to support deployment of BIER into a network in a manner that continues to support use of Protocol Independent Multicast (PIM) for multicast control within the network. The multicast capability may be configured to support deployment of BIER, into a network including an Interior Gateway Protocol (IGP) area, using a BIER domain that is commensurate with the IGP area or that is only a portion of the IGP area. The multicast capability may be configured to support deployment of BIER into a network in a manner supporting stitching of traditional PIM access networks via a BIER core network.