OpenFlow Switch Controller Discovery Without DHCP

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Solution Overview

Problem

Current methods for controller discovery in OpenFlow configured optical communication networks are inefficient, particularly in large networks, as they rely on broadcast-based protocols like DHCP, which limits scalability and only function after IP connectivity is established.

Innovation Solution

A method and apparatus that utilize an OpenFlow capable switch to discover a controller without relying on DHCP, using an out-of-band or in-band communication link discovery protocol, where a link discovery protocol packet is sent from eligible switch ports, ensuring guaranteed responses through mechanisms like Time To Live, and updating a database with the controller's IP address upon successful discovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If DHCP protocol is used for controller discovery, then IP connectivity can be established, but scalability is limited due to broadcast overhead in large networks

Engineering Contradiction:

Improvecontroller discovery reliabilityVSAvoidnetwork scalability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the broadcast-based DHCP mechanical system with an OpenFlow control plane message-based discovery mechanism. The controller discovery is achieved through targeted control messages (CONTROLLER_REQUEST, CONTROLLER_ADVERTISEMENT) instead of broadcast DHCP packets, eliminating the fundamental limitation of broadcast overhead while maintaining reliable discovery through the structured OpenFlow protocol framework

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If standard DHCP mechanism is used, then controller discovery is possible, but it only functions after IP connectivity is established

Engineering Contradiction:

Improvecontroller discovery capabilityVSAvoidnetwork convergence time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent implements preliminary controller discovery actions through pre-configured OpenFlow controller connections and pre-established control plane communication channels. The controller discovery process begins before data plane IP connectivity is needed, using pre-configured controller IP addresses and port information to initiate control messages, thereby reducing network convergence time by performing discovery in advance

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If DHCP relays are deployed for beyond subnet discovery, then controller discovery range is extended, but device complexity and configuration overhead increase

Engineering Contradiction:

Improvecontroller discovery rangeVSAvoidnetwork configuration complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes the OpenFlow control plane universally applicable for controller discovery across all network segments and subnets. The control messages can traverse multiple subnets and routers using standard IP routing, eliminating the need for specialized DHCP relay configurations. The same OpenFlow controller and message format work uniformly whether the switch is in the same subnet or a different subnet, providing multi-functional discovery capability without additional complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9729948B1Systems and methods for discovery of a controller in openflow networks

Publication Date: 2017.08.08 INFINERA CORP

AI summary

Systems and methods for discovery of a controller in an OpenFlow network may include using an OpenFlow capable switch to discover the controller without the help of other components, such as DHCP. The link discovery protocol may be configured on the switch and the discovery process may use an out-of-band or an in-band communication. In one example, a link discovery protocol packet is sent out of all ports of a switch that meet the eligibility criteria. The response is guaranteed because of a TTL like mechanism in the packet. Each port on a switch that receives this link discovery protocol packet takes an action depending on its current state.