Router Session Resilience via Priority Queue Redistribution

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Solution Overview

Problem

In router platforms, when a line card fails, existing methods either result in service loss for subscriber sessions or cause packet loss during redistribution, and the addition of a new line card leads to underutilization of resources due to inefficient redistribution processes.

Innovation Solution

Classifying subscriber sessions into priority queues and redistributing them to available line cards in a prioritized order to minimize packet loss and maximize session retention, and efficiently utilizing new line cards by redistributing sessions based on load balancing algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If subscriber sessions are redistributed using random order or time sequence, then the redistribution process is simple to implement, but packet loss occurs during the redistribution process

Engineering Contradiction:

Improvesession retentionVSAvoidredistribution mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments subscriber sessions into multiple priority queues based on their characteristics and requirements. Each queue handles sessions with different priorities, allowing the system to redistribute sessions in an optimized order rather than using a single random or time-based sequence. This segmentation enables differentiated handling that reduces packet loss while maintaining manageable system complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter of session redistribution from random or time-based ordering to priority-based ordering. By introducing priority levels and corresponding queues, the system transforms the redistribution mechanism into a more reliable process that minimizes packet loss. The priority parameter allows sessions to be reordered based on their importance and characteristics.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If all subscriber sessions are redistributed to new line cards, then load balancing is improved, but packet loss occurs for sessions being moved

Engineering Contradiction:

Improveload balancing efficiencyVSAvoidsession continuity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by prioritizing certain sessions for redistribution before others. High-priority sessions are handled first in the redistribution process, ensuring their continuity is maintained. This preliminary handling of critical sessions allows load balancing to proceed efficiently while protecting session continuity for important traffic.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent ensures continuity of useful action by maintaining active session handling throughout the redistribution process. Priority queues ensure that sessions are continuously processed in an optimized sequence, preventing interruptions and packet loss. The redistribution maintains continuous service delivery while achieving load balancing goals.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If no redistribution is performed when a line card fails, then session stability is maintained, but service loss occurs for all sessions on the failed card

Engineering Contradiction:

Improvesession stabilityVSAvoidservice availability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by treating different sessions with different qualities of service during redistribution. Rather than applying a uniform approach to all sessions, the system identifies and prioritizes specific sessions based on their characteristics. This localized differentiation ensures that critical sessions receive enhanced protection while allowing efficient redistribution overall.

Inventive Principle:

Principle #3Local quality

4Adaptability or versatility

If new line cards are added to the system, then system capacity is increased, but resource underutilization occurs due to inefficient redistribution

Engineering Contradiction:

Improvesystem capacityVSAvoidresource utilization

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent introduces dynamics into the redistribution process by using adaptive priority queues that can respond to changing system conditions. When new line cards are added, the system dynamically adjusts the redistribution strategy, prioritizing sessions appropriately to maximize utilization of available resources. This dynamic approach ensures that system capacity increases translate into improved resource utilization rather than underutilization.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8254249B2Session resilience prioritization queuing mechanism to minimize and eliminate packet loss

Publication Date: 2012.08.28 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method for managing a plurality of subscriber sessions tied to mobile devices in a router, each subscriber session of the plurality of subscriber sessions assigned to a line card in the router, the line card implementing a data plane entity and a control card implementing a control plane entity, the method comprising: redistributing each subscriber session in the plurality of subscriber sessions assigned to a failed line card in the router to minimize packets lost and maximize subscriber session retention, redistributing including classifying each subscriber session in the plurality of subscriber sessions into a plurality of priority queues, in response to detection of the failed line card, transferring each subscriber session in the plurality of subscriber sessions assigned to the failed line card to one of a plurality of operating line cards in priority queue order.