Forwarding Inter-Switch Connection Frames in NNI Topologies

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Solution Overview

Problem

Existing Network-to-Network Interconnect (NNI) topologies face challenges in efficiently forwarding Inter-Switch Connection (ISC) frames across distinct networks with separate management and administration, often requiring costly hardware for frame tagging or encapsulation to avoid network bottlenecks and maintain high availability.

Innovation Solution

The solution involves using a method that allows sharing a single physical link for both local network and NNI traffic without tagging or encapsulation, utilizing logical connections to manage frame forwarding based on Virtual Local Area Network Identifiers (VLAN IDs) and implementing primary and secondary forwarders to ensure frames are delivered across the NNI only once, thereby avoiding duplication and maintaining network resilience.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frame tagging or encapsulation is implemented to identify local traffic vs. NNI traffic, then frame forwarding accuracy is improved, but device complexity and hardware cost increase significantly

Engineering Contradiction:

Improveframe forwarding accuracyVSAvoidhardware complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the traffic identification function from complex frame tagging/encapsulation mechanisms and implements it through a simpler VLAN ID-based classification system. The switching element examines VLAN IDs in incoming frames to determine whether they are local or NNI traffic, eliminating the need for costly hardware tagging or encapsulation schemes while maintaining accurate frame forwarding.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces VLAN IDs as an intermediary mechanism to identify and differentiate between local and NNI traffic. Instead of using complex frame tagging or encapsulation, the system uses VLAN ID examination as a中介 to route frames appropriately through the switching element, simplifying the forwarding decision process without sacrificing accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If redundant nodes and links are deployed to ensure NNI availability, then network reliability is improved, but device complexity and cost increase

Engineering Contradiction:

ImproveNNI availabilityVSAvoidnetwork topology complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple NNIs to share a common ISC link, allowing the same physical infrastructure to support multiple network interconnections. This consolidation reduces the total number of redundant components needed while maintaining availability through logical redundancy management, thereby lowering device complexity and cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent enables a single ISC link to serve multiple NNIs simultaneously, making the link multi-functional. The switching element intelligently manages traffic from different NNIs over the shared link, allowing one physical connection to fulfill multiple roles and reducing the need for dedicated redundant hardware for each NNI.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Quantity of substance

If multiple NNIs share a common ISC link, then hardware cost is reduced, but frame forwarding complexity increases

Engineering Contradiction:

Improvehardware resourcesVSAvoidframe forwarding logic

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent performs preliminary classification of incoming frames based on their VLAN IDs before forwarding decisions are made. The switching element examines the VLAN ID field in each frame to pre-determine whether it is local or NNI traffic, enabling efficient routing without complex real-time analysis and reducing overall forwarding complexity despite multiple NNIs sharing the link.

Inventive Principle:

Principle #10Preliminary action

4Productivity

If frame duplication is prevented in multi-NNI topologies, then network efficiency is improved, but forwarding logic complexity increases

Engineering Contradiction:

Improvenetwork efficiencyVSAvoidforwarding logic

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the switching element tracks which NNIs have already received specific frames. When a frame is forwarded to one NNI, the system uses this feedback information to prevent duplicate forwarding to other NNIs, maintaining network efficiency through intelligent frame delivery control without requiring overly complex forwarding logic.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9882838B2Forwarding inter-switch connection (ISC) frames in a network-to-network interconnect topology

Publication Date: 2018.01.30 EXTREME NETWORKS INC

AI summary

Systems, mechanisms, apparatuses, and methods are disclosed for forwarding Inter-Switch Connection (ISC) frames in a Network-to-Network Interconnect (NNI) topology, for example, via a network switch which includes a first physical switch port to receive a physical switch link from a second network switch; logic to implement a first logical ISC and a second logical ISC′ connection to the second network switch via the physical switch link; a second physical switch port to receive an interface connection from a third network switch; and switch forwarding logic to forward frames received at the first network switch to the second network switch via the logical ISC or logical ISC′ based on whether or not the physical switch link is part of an active topology upon which the network switch operates or is not part of the active topology upon which the network switch operates. Other embodiments are disclosed.