SR/LDP Mapping Server for Network Interoperability

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Solution Overview

Problem

The integration of Segment Routing (SR) and Label Distribution Protocol (LDP) enabled nodes in a network domain faces challenges due to differences in packet forwarding mechanisms, making it difficult to implement hybrid networks that include both SR and LDP nodes, as SR nodes cannot exchange labels with LDP nodes, and LDP nodes lack the ability to forward packets based on segment IDs.

Innovation Solution

The introduction of SR/LDP nodes that bridge the differences between SR and LDP nodes by mapping segment IDs to LDP node loopbacks and advertising these mappings, enabling packet transfer between SR and LDP nodes through the use of SR mapping nodes that create or update forwarding tables and segment ID stacks, allowing for the creation of hybrid networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If SR nodes and LDP nodes are integrated in a network domain, then network flexibility and performance are improved, but interoperability challenges arise due to different packet forwarding mechanisms

Engineering Contradiction:
Improvenetwork flexibilityVSAvoidinteroperability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces mapping servers and SR/LDP boundary nodes as intermediary components that translate between SR segment IDs and LDP labels. These intermediaries enable seamless communication between SR and LDP domains by converting packet forwarding identifiers, allowing SR nodes to forward packets to LDP nodes and vice versa without direct protocol compatibility requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent transforms packet forwarding by changing the identifier parameter used in different network domains. SR nodes use segment IDs while LDP nodes use labels; the mapping server establishes correspondence between these different parameter systems, allowing packets to be forwarded using SR segment IDs in the SR domain and automatically translated to appropriate LDP labels when entering the LDP domain.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If SR nodes cannot exchange labels with LDP nodes, then protocol simplicity is maintained, but hybrid network creation is prevented

Engineering Contradiction:
Improveprotocol simplicityVSAvoidhybrid network capability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

Mapping servers act as intermediaries that maintain protocol simplicity for SR and LDP nodes while enabling hybrid network creation. The mapping server stores and manages the correspondence between SR segment IDs and LDP labels, allowing SR nodes to continue using segment IDs and LDP nodes to use labels without requiring direct label exchange between them.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the network into distinct SR domains and LDP domains with mapping servers positioned at the boundaries. This segmentation allows each domain to maintain its own simple protocol operations while the boundary mapping servers handle the complexity of inter-domain translation, enabling hybrid network capability without compromising intra-domain protocol simplicity.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If LDP nodes lack the ability to forward packets based on segment IDs, then LDP forwarding mechanism remains simple, but SR-LDP integration is blocked

Engineering Contradiction:
ImproveLDP forwarding simplicityVSAvoidpacket transfer capability
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

SR/LDP boundary nodes serve as intermediaries that receive packets with SR segment IDs from the SR domain, translate the segment ID to the corresponding LDP label using mapping information, and forward the packet using the LDP label in the LDP domain. This allows LDP nodes to maintain their simple label-based forwarding mechanism while enabling seamless packet transfer from SR nodes.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The boundary nodes perform parameter transformation by converting the packet forwarding identifier from SR segment ID format to LDP label format. This parameter change enables packets to traverse from the SR domain through the LDP domain without requiring LDP nodes to understand or process segment IDs, maintaining LDP forwarding simplicity while achieving integration.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2997699B1Segment routing mapping server for LDP/SR interoperability
Publication Date: 2020.03.04 CISCO TECHNOLOGY INC
  • EP2997699B1 patent drawingFigure 1
  • EP2997699B1 patent drawingFigure 2
  • EP2997699B1 patent drawingFigure 3

AI summary

An apparatus and method for enabling interoperability of segment routing (SR) enabled nodes and LDP enabled nodes in a network domain. In one embodiment, the method may include mapping a first node identifier (ID) to a first segment ID in memory, wherein the first node ID uniquely identifies a first node within a network domain, and wherein the first node is not SR enabled. A message is generated and subsequently transmitted directly or indirectly to another node within the network domain, wherein the message comprises the first node ID mapped to the first segment ID, and wherein the other node is SR enabled.