Network Topology Discovery via Link Classification

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Solution Overview

Problem

In communication networks, it is challenging for controllers to determine appropriate network forwarding paths due to the presence of non-client switches that do not communicate with the controller, making it difficult to maintain network topology information and manage networks with equipment from multiple vendors.

Innovation Solution

A controller maintains a link discovery table by sending and processing discovery packets to classify links between client switches, identifying direct and broadcast links, and using this information to classify switch ports and determine network domains, thereby establishing a network domain topology.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a controller attempts to control all switches in a network including non-client switches, then complete network topology control is achieved, but device complexity and control difficulty increase significantly due to vendor incompatibility

Engineering Contradiction:

Improvenetwork topology controlVSAvoidcontroller complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The network is segmented into client switches (controlled by the controller) and non-client switches (uncontrolled). The controller focuses on discovering and managing only the client switches and their interconnections, rather than attempting to control all switches. This segmentation allows the controller to maintain topology awareness without the complexity of controlling heterogeneous vendor equipment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The controller implements a universal discovery mechanism that works across multi-vendor environments by sending standardized discovery packets to all switches. This universal approach allows the controller to gather topology information from both client and non-client switches without requiring vendor-specific control capabilities, thus reducing controller complexity while maintaining reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If discovery packets are sent frequently to maintain accurate topology information, then measurement precision of network topology is improved, but network traffic overhead and processing time increase

Engineering Contradiction:

Improvetopology information accuracyVSAvoiddiscovery packet processing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The controller sends discovery packets periodically at configured intervals rather than continuously or on every topology change event. This periodic action maintains adequate topology information accuracy while significantly reducing the frequency of discovery operations and associated processing time overhead on the network.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Client switches automatically respond to discovery packets by forwarding them to the controller with their identity information. This self-service mechanism allows the controller to obtain topology information efficiently without requiring complex active probing or repeated verification, reducing processing time while maintaining accuracy.

Inventive Principle:

Principle #25Self-service

3Loss of information

If the controller discovers and classifies all links in the network, then network topology information completeness is improved, but the quantity of processing data and computational requirements increase

Engineering Contradiction:

Improvetopology information completenessVSAvoidtopology processing efficiency

Core Design Contradiction:

Loss of informationVSProductivity

Solution Approach 1:

The controller extracts only the essential topology information needed for forwarding decisions, specifically the identities of client switches and their interconnections. Non-essential details about non-client switches and internal link configurations are not processed or stored, reducing data quantity and computational requirements while maintaining sufficient topology completeness for network control.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The controller performs preliminary classification of links as direct or broadcast during the initial discovery phase. This preliminary action organizes the topology data into structured categories before further processing, reducing the computational complexity of subsequent routing calculations and improving overall processing efficiency.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9654380B1Systems and methods for determining network topologies

Publication Date: 2017.05.16 ARISTA NETWORKS INC

AI summary

A controller may control client switches in a network including client and non-client switches. The controller may maintain a link discovery table including entries that identify links between client switches. The controller may classify the links as direct or broadcast links. To classify links of the link discovery cable, the controller may direct client switches to send broadcast and directed discovery packets from switch ports. Client switches that receive the discovery packets from other client switches may forward the discovery packets to the controller. The controller may use the discovery packets to classify the links of the link discovery table. The controller may classify ports as broadcast or regular ports based on the classified links. Non-client broadcast domains of the network topology may be identified from the broadcast ports using the broadcast and direct links of the link discovery table.