Segment Routing Multicast Identifier Distribution for Accurate Forwarding

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Solution Overview

Problem

The Interior Gateway Protocol and Border Gateway Protocol (BGP) have not clearly defined the distribution and learning of multicast segment identifiers in segment routing label networks, leading to errors in the use of multicast segment identifiers.

Innovation Solution

A method for supporting multicast in segment routing label networks by advertising a network node's host address with a multicast segment identifier, allowing nodes to multicast or unicast forward traffic based on the identifier, and defining the distribution and learning of multicast segment identifiers using ISIS, OSPF, and BGP protocols.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing gateway protocols (IGP and BGP) are used without clear definition, then device complexity is reduced and ease of operation is maintained, but multicast segment identifier distribution and learning become error-prone and unreliable

Engineering Contradiction:
Improvemulticast segment identifier distribution and learningVSAvoidprotocol definition and implementation
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extends existing gateway protocols by introducing new parameters: multicast segment identifiers, a multicast flag bit in TLV structures, and specific sub-TLV fields for multicast information. These parameter changes enable reliable multicast segment identifier distribution while maintaining compatibility with existing protocol frameworks, thus improving reliability without requiring complete protocol redesign

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the routing information by introducing distinct TLV (Type-Length-Value) structures and sub-TLV fields specifically for multicast segment identifiers. This segmentation allows multicast-specific information to be carried separately within the existing protocol framework, enabling clear definition and reliable distribution of multicast identifiers without affecting unicast routing operations

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If multicast segment identifiers are not clearly defined in gateway protocols, then protocol simplicity is maintained, but forwarding accuracy and precision deteriorate

Engineering Contradiction:
Improvemulticast segment identifier usage accuracyVSAvoidprotocol structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces intermediary structures (TLV headers, sub-TLV fields, and multicast flag bits) that act as mediators between the existing gateway protocol framework and multicast segment identifier requirements. These intermediaries provide a structured way to carry and identify multicast information, improving usage accuracy without fundamentally changing the underlying protocol architecture

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent establishes preliminary actions by defining specific TLV types and sub-TLV structures that pre-configure multicast segment identifier distribution mechanisms. By pre-defining these structures in the protocol specification, the patent ensures accurate multicast identifier handling from the outset, eliminating the need for ad-hoc implementations that would reduce precision

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4668700A1Method and device for supporting segment routing label network multicast, and medium
Publication Date: 2025.12.24 ZTE CORP
  • EP4668700A1 patent drawingFigure 1~2
  • EP4668700A1 patent drawingFigure 3~4
  • EP4668700A1 patent drawingFigure 5

AI summary

The present application relates to the technical field of communications, and discloses a method and device for supporting segment routing label network multicast, and a medium. The method is applied to a network node executing a multicast forwarding operation in a segment routing label network, and comprises: notifying other network nodes in the segment routing label network of a first host address of the current network node, wherein the first host address is configured with a first multicast segment identifier of the current network node, the first multicast segment identifier is used for instructing the current network node to forward first traffic in a multicast mode, and is used for instructing the other network nodes in the segment routing label network to forward the first traffic in a unicast mode, and the first traffic is traffic having forward information matching the first multicast segment identifier.