Upstream PORT Routing Link Switchover

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional link switchover processes in multicast protocols result in packet loss and delay due to the downstream routing elements waiting for routing information convergence before selecting a new forwarding interface, even when an alternate active link is available.

Innovation Solution

The proposed solution moves the link switchover logic from downstream to upstream PORT routing elements, allowing the upstream element to select and install a new forwarding interface for multicast datastreams, reducing downtime and packet loss by performing link switchover without waiting for routing convergence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If downstream routing elements wait for routing information convergence before selecting a new forwarding interface, then routing stability is maintained, but packet loss and delay increase

Engineering Contradiction:

Improverouting stabilityVSAvoidswitchover delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent pre-establishes multiple candidate forwarding interfaces and performs preliminary routing calculations at downstream routing elements. When a link failure occurs, the system can immediately switch to a pre-identified candidate interface without waiting for full routing convergence, thus reducing switchover delay while maintaining routing stability through pre-validation of candidate paths

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism where downstream routing elements maintain a list of candidate forwarding interfaces and communicate link status changes to upstream elements. This intermediary layer allows for faster local decision-making at the downstream element while still coordinating with upstream elements, balancing speed with stability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If downstream routing elements perform link switchover after routing convergence, then correct routing paths are ensured, but packet loss occurs during the waiting period

Engineering Contradiction:

Improverouting path accuracyVSAvoidpacket loss

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent pre-calculates and stores multiple valid forwarding interfaces at downstream routing elements before any failure occurs. These candidate interfaces are pre-validated to ensure they lead to correct routing paths. When a link fails, the system immediately activates a pre-validated candidate interface, eliminating packet loss during the switchover while ensuring routing path accuracy through pre-validation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent prepares backup forwarding interfaces in advance as a cushion against potential link failures. By maintaining pre-validated candidate interfaces ready for immediate activation, the system cushions against packet loss that would otherwise occur during routing convergence, while ensuring the backup paths are pre-validated for correctness

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Speed

If upstream PORT routing elements perform link switchover, then switchover speed increases, but downstream element coordination becomes more complex

Engineering Contradiction:

Improvere-routing speedVSAvoidswitchover coordination complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent extracts the link switchover decision-making function from downstream routing elements and relocates it to upstream PORT routing elements. This extraction simplifies the downstream elements by removing the complex logic of candidate interface management and switchover timing, while the upstream elements handle the switchover based on notifications from downstream elements, achieving fast re-routing without over-complicating downstream devices

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS9246797B2PORT based redundant link protection

Publication Date: 2016.01.26 CISCO TECHNOLOGY INC

AI summary

The present disclosure provides for avoiding packet loss and delay that occurs during conventional link switchover by moving link switchover logic from a downstream PORT (Protocol Independent Multicast Over Reliable Transport) routing element to an upstream PORT routing element. An upstream PORT routing element detects the failure of a forwarding interface for a multicast datastream, where the forwarding interface is coupled to a downstream PORT routing element. In response to detecting the failure, the upstream PORT routing element determines a set of candidate interfaces that are also coupled to the downstream PORT routing element. The upstream PORT routing element selects a new interface from the set of candidate interfaces and installs the new interface as a replacement forwarding interface for the multicast datastream.