SDN Path Switch Coordination via Controller-Mediated End Markers

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Solution Overview

Problem

The existing 3GPP wireless network path switch coordination mechanism, which relies on 'end-markers' for packet reordering, is not compatible with evolving software-defined networking (SDN) architectures proposed for 5G, as signaling functions like end-markers cannot be sent by switches in these architectures.

Innovation Solution

A method where a controller instructs a switch to change from one tunnel to another, receives acknowledgement, and notifies network elements that no further packets will be sent via the first tunnel, using a sequence number if necessary, to manage path switching in SDN architectures, ensuring seamless resource allocation and de-allocation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the traditional 3GPP path switch coordination mechanism using end-markers is used, then packet reordering can be assisted in the target base station, but it is not compatible with SDN architectures where signaling functions must be centralized

Engineering Contradiction:

Improvecompatibility with SDN architectureVSAvoidsignaling function distribution

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the end-marker signaling function from the data plane (switch) and relocates it to the control plane (controller). The controller now generates end-marker messages and sends them to network elements through the control plane, separating signaling functions from data forwarding functions. This extraction enables compatibility with SDN architecture while maintaining packet reordering assistance capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The controller acts as an intermediary between the switch and network elements for end-marker signaling. Instead of switches directly sending end-markers to network elements, the controller mediates this communication by receiving path switch instructions from switches, generating appropriate end-marker messages, and forwarding them to the relevant network elements through the control plane.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Extent of automation

If switches send end-markers directly in the data plane, then path switching can be coordinated locally, but centralized control required for SDN architecture cannot be maintained

Engineering Contradiction:

Improvecentralized controlVSAvoidlocal path switching coordination

Core Design Contradiction:

Extent of automationVSEase of operation

Solution Approach 1:

The patent segments the path switching coordination function into two parts: local data plane actions (switch receiving path switch instructions and tearing down tunnels) and centralized control plane actions (controller generating and sending end-marker messages). This segmentation allows both centralized automation and local operational simplicity to coexist.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The controller receives feedback from switches about path switching status (when switches send acknowledgments indicating no further data packets will be sent via the first tunnel). This feedback mechanism enables the controller to accurately track path switch status and send appropriate end-marker messages to network elements, maintaining centralized control while allowing local switch operations.

Inventive Principle:

Principle #23Feedback

3Reliability

If path switching is implemented without proper coordination signaling, then network elements can quickly adapt to new paths, but packet reordering may be affected and resources not properly released

Engineering Contradiction:

Improvepacket reorderingVSAvoidresource release timing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The controller performs preliminary actions by sending end-marker messages to network elements before actually tearing down the tunnel. This ensures that network elements are prepared to stop expecting packets on the first tunnel path, allowing for reliable packet reordering and timely resource release without waiting for packet flow to naturally terminate.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical/data-plane based end-marker sending mechanism with a control-plane based messaging system. The controller uses structured control messages to coordinate path switching, providing more precise and reliable timing control for resource release compared to traditional data-plane end-markers.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9516554B2Method of coordinating a path switch and network elements associated therewith

Publication Date: 2016.12.06 ALCATEL LUCENT SA

AI summary

In one embodiment, the method includes instructing, by a controller, a switch to change from sending data via a first tunnel to sending data via a second tunnel. The first tunnel is between the switch and a first network element, and the second tunnel is between the switch and a second network element. The method further includes receiving, by the controller, acknowledgement from the switch, and notifying, by the controller, the second network element that packets will no longer be sent via the first tunnel in response to the received acknowledgement.