SRMS Mediator for Non-Flexible Router Inclusion in Flexible-Algorithm Routing

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Solution Overview

Problem

Current routing protocols, such as Interior Gateway Protocols (IGPs), often exclude non-flexible-algorithm routers from path computations, limiting their participation in flexible-algorithm path computations, especially in multi-vendor networks where not all routers support flexible-algorithm techniques.

Innovation Solution

Incorporating non-flexible-algorithm routers into flexible-algorithm path computations by using existing Type, Length, and Value (TLV) fields in Open Shortest Path First (OSPF) and Intermediate System - Intermediate System (ISIS) packets, where a Segment Routing Mapping Server (SRMS) advertises loopback addresses and flexible-algorithm identifiers to enable their inclusion, allowing routers to configure forwarding information to steer traffic through these routers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If flexible-algorithm path computations are implemented using existing IGP protocols, then non-flexible-algorithm routers can be included in the network, but protocol complexity increases due to the need for extended TLV fields and synchronization mechanisms

Engineering Contradiction:
Improverouter participationVSAvoidprotocol complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces a Segment Routing Mapping Server (SRMS) as an intermediary component that generates and distributes mapping information for non-flexible-algorithm routers. The SRMS creates Type-Length-Value (TLV) structures containing loopback address to router identifier mappings, which are then distributed to flexible-algorithm routers through existing IGP protocols. This intermediary approach allows non-flexible-algorithm routers to participate in flexible-algorithm path computations without requiring protocol modifications to the routers themselves, thus resolving the contradiction between adaptability and protocol complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the flexible-algorithm implementation into distinct functional components: (1) the SRMS that handles mapping information generation and distribution, (2) the flexible-algorithm routers that perform path computations using the mapping information, and (3) the non-flexible-algorithm routers that are included in paths without needing to understand flexible-algorithm protocols. This segmentation allows each component to have specialized functionality, reducing overall system complexity while maintaining high adaptability.

Inventive Principle:
Principle #1Segmentation

2Productivity

If flexible-algorithm path computations are implemented across the entire network, then traffic engineering capabilities are enhanced, but implementation difficulty increases due to the need for synchronized routing topology information across all routers

Engineering Contradiction:
Improvetraffic engineering capabilityVSAvoidimplementation difficulty
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The patent implements flexible-algorithm path computations partially, only in the flexible-algorithm domain where needed, rather than requiring all routers in the entire network to support flexible-algorithm protocols. The SRMS generates mapping information only for non-flexible-algorithm routers that need to be included in flexible-algorithm paths, and distributes this information only to flexible-algorithm routers. This partial implementation approach enhances traffic engineering capabilities in the flexible-algorithm domain without requiring network-wide protocol changes, thus reducing implementation difficulty.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent performs preliminary actions by having the SRMS pre-generate and distribute mapping information (TLV structures containing loopback address to router identifier mappings) to flexible-algorithm routers before flexible-algorithm path computations are performed. This preliminary distribution of mapping information ensures that all flexible-algorithm routers have synchronized routing topology information about non-flexible-algorithm routers, eliminating the need for complex real-time synchronization mechanisms during path computations and simplifying implementation.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If non-flexible-algorithm routers are excluded from flexible-algorithm path computations, then protocol implementation is simpler, but network adaptability decreases and traffic engineering flexibility is limited

Engineering Contradiction:
Improveprotocol implementation simplicityVSAvoidnetwork adaptability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The SRMS acts as an intermediary that translates between the simple world of non-flexible-algorithm routers and the complex world of flexible-algorithm path computations. By generating and distributing mapping information that translates loopback addresses to router identifiers, the SRMS enables non-flexible-algorithm routers to be included in flexible-algorithm paths without requiring these routers to implement complex flexible-algorithm protocols themselves. This maintains protocol implementation simplicity for the majority of routers while achieving network adaptability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a virtual representation or copy of non-flexible-algorithm routers within the flexible-algorithm domain through the mapping information generated by the SRMS. The TLV structures contain loopback address to router identifier mappings that create a virtual model of non-flexible-algorithm routers, allowing flexible-algorithm routers to compute paths through these virtual representations. This copying approach enables network adaptability by including non-flexible-algorithm routers in flexible-algorithm paths while maintaining protocol implementation simplicity, as the complex mapping logic resides only in the SRMS.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP3648420B1Enabling non-flexible-algorithm routers to participate in flexiblealgorithm routing protocols
Publication Date: 2021.09.22 JUNIPER NETWORKS INC
  • EP3648420B1 patent drawingFigure 1
  • EP3648420B1 patent drawingFigure 2A~2B
  • EP3648420B1 patent drawingFigure 3

AI summary

Techniques are described for facilitating the inclusion of a non-flexible-algorithm router to be included in flexible-algorithm path computations. For example, a flexible-algorithm router advertises information associated with a non-flexible-algorithm router to other flexible-algorithm routers in the network such that the flexible-algorithm routers may include the non-flexible-algorithm router when computing a path based on flexible-algorithm. During path computation, if the router determines that its next-hop router is the non-flexible-algorithm router, the router may configure additional forwarding information to cause the router to steer traffic to the non-flexible-algorithm router.