Split-Plane AP SSID Hiding During WCP Failure

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Solution Overview

Problem

Current solutions for wireless network failover in split-plane architecture do not adequately address the issue of maintaining connectivity for roaming mobile units during a Wireless Control Plane (WCP) failure, leading to service disruptions as the affected Access Points (APs) continue to operate without complete WCP access, while also failing to leverage the benefits of cellular redundancy.

Innovation Solution

The proposed solution involves detecting WCP failures by APs in split-plane deployments, hiding their SSIDs in beacons, caching information for existing mobile units, and responding only to probes from cached units, allowing affected APs to appear hidden to new units while maintaining service for existing ones, and using cellular redundancy to establish temporary connections with neighboring APs for WCP functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If affected APs continue to broadcast SSIDs in beacons after WCP failure, then new mobile units can associate with the AP, but the AP cannot properly authenticate or manage these new units without WCP access

Engineering Contradiction:

Improveability to accept new associationsVSAvoidauthentication reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent inverts the normal behavior by having the AP hide its SSID in beacons after WCP failure, instead of broadcasting it to attract new associations. This prevents new MUs from attempting to associate with an AP that cannot properly authenticate them, while still allowing existing MUs to maintain connections through cached credentials.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If affected APs hide their SSIDs in beacons to prevent new associations, then authentication reliability is maintained, but existing mobile units cannot discover or reconnect to the AP after roaming away

Engineering Contradiction:

Improveauthentication reliabilityVSAvoidreconnection ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent creates a copy of the SSID information and stores it in the information element cache within the AP. This cached copy is used to respond to probe requests from existing MUs, allowing them to discover and reconnect to the AP even though the SSID is hidden in beacons. This resolves the contradiction by providing selective visibility - hidden from new MUs but visible to existing ones.

Inventive Principle:

Principle #26Copying

3Adaptability or versatility

If the AP responds to all probe requests, then new mobile units can discover the AP, but the AP wastes resources processing probes from units that cannot be properly authenticated without WCP

Engineering Contradiction:

Improvediscovery capabilityVSAvoidAP processing energy

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by differentiating the AP's response behavior based on the source of the probe request. Probes from MUs with cached information receive responses, while probes from new MUs without cached information are ignored. This selective response strategy reduces energy waste on impossible authentications while maintaining service for legitimate existing clients.

Inventive Principle:

Principle #3Local quality

4Reliability

If the AP caches information for existing mobile units, then service continuity is maintained during WCP failure, but the AP consumes additional memory resources

Engineering Contradiction:

Improveservice continuityVSAvoidmemory resources

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent implements partial action by caching only the essential information needed for basic authentication and service continuity (such as MU identifiers and basic credentials) rather than storing complete session state. This allows the AP to maintain service for existing MUs during WCP failure while consuming minimal memory resources, accepting that full functionality will be restored when WCP connectivity returns.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS8824323B2Wireless control plane failure handling in a split-plane deployment

Publication Date: 2014.09.02 SIGNAL POINT NETWORKS LLC

AI summary

A method, apparatus and computer program product for providing wireless control plane failover handling in a split-plane deployment is presented. A first AP in a split-plane deployment detects failure of a Wireless Control Plane (WCP) device. The first AP hides an SSID in beacons broadcast by the first AP. The first AP stores information for existing Mobile Units (MUs) that dissociate after the detection of the failure of the WCP device. The first AP will respond to probes from existing MUs; and also respond to probes from MUs that have their information stored in the AP, such that the first AP appears hidden from new MUs while being exposed to existing MUs.