SDN Controller Deadlock-Free Traffic Rerouting

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Solution Overview

Problem

SDN networks face challenges in rerouting traffic without causing transient deadlocks and bandwidth oversubscription, leading to potential network failures due to congestion.

Innovation Solution

A centralized SDN controller determines and initiates rerouting of packet flows to new paths, requesting initial small bandwidth to avoid oversubscription and then adjusts to desired bandwidth levels, ensuring deadlock-free traffic rerouting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional rerouting approach is used to improve network adaptability, then new services can be activated and existing services updated on-demand, but transient deadlocks and bandwidth oversubscription occur leading to network failures

Engineering Contradiction:

Improvenetwork adaptabilityVSAvoidnetwork reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The SDN controller performs preliminary bandwidth reservation and path validation before initiating traffic rerouting. By预先 (in advance) calculating the new path and reserving necessary bandwidth, the system ensures that rerouting can proceed without causing deadlocks or oversubscription, thus maintaining network reliability while enabling adaptability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where the SDN controller continuously monitors network state, bandwidth utilization, and path availability. Based on this feedback, the controller dynamically adjusts rerouting decisions and bandwidth allocations, preventing deadlocks while maintaining the ability to adapt to changing network conditions

Inventive Principle:

Principle #23Feedback

2Reliability

If full bandwidth is allocated to new path during rerouting to maintain service quality, then traffic flow can be successfully rerouted, but bandwidth oversubscription occurs on the new path causing congestion

Engineering Contradiction:

Improvererouting successVSAvoidbandwidth oversubscription

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Instead of allocating full bandwidth immediately, the system uses partial bandwidth allocation during the transition phase. The SDN controller allocates only the necessary portion of bandwidth for the rerouted traffic flow, avoiding oversubscription while still enabling successful rerouting. This partial action principle prevents congestion on the new path

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system dynamically changes bandwidth allocation parameters during the rerouting process. The SDN controller adjusts bandwidth reservations based on the current state of the new path, increasing allocation gradually as the path becomes available and decreasing it when congestion is detected, thus preventing oversubscription while ensuring rerouting success

Inventive Principle:

Principle #35Parameter changes

3Speed

If routers perform distributed rerouting to resolve congestion quickly, then local congestion can be addressed, but deadlock situations arise when multiple routers attempt simultaneous rerouting

Engineering Contradiction:

Improvecongestion resolution speedVSAvoidrerouting stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The control function for rerouting is extracted from the distributed routers and centralized in the SDN controller. This extraction eliminates the deadlock problem caused by simultaneous distributed decisions, as the centralized controller coordinates rerouting globally. The routers focus only on fast packet forwarding while the controller handles the complex rerouting logic

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The SDN controller acts as an intermediary between the network traffic and the routers. It receives rerouting requests, calculates optimal paths considering global network state, and instructs routers on how to reroute. This intermediary coordination prevents deadlocks by ensuring that rerouting decisions are made in a coordinated manner rather than simultaneously by multiple routers

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10728140B2Deadlock-free traffic rerouting in software-deifned networking networks

Publication Date: 2020.07.28 AT&T INTELLECTUAL PROPERTY I L P

AI summary

Concepts and technologies disclosed herein are directed to deadlock-free traffic rerouting in software-defined networking (“SDN”) networks. According to one aspect of the concepts and technologies disclosed herein, a centralized SDN controller can determine that a packet flow along a path within at least a portion of a network is to be rerouted from the path to a new path. The centralized SDN controller can initiate a reroute of the packet flow to the new path. The centralized SDN controller can request a bandwidth for the new path. The bandwidth can be determined such that bandwidth oversubscription on the new path is avoided. In response to the packet flow settling on the new path, the centralized SDN controller can adjust a requested bandwidth of the packet flow to a desired value to complete the reroute of the packet flow from the path to the new path.