ERP MAC-Flush Rerouting for Multihomed Ethernet Ring Traffic Loss

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Solution Overview

Problem

In Ethernet Ring multihomed networks, data traffic loss occurs due to link failures between customer sites and service provider networks, as existing Ethernet Ring Protection (ERP) protocols do not effectively reroute traffic when the failure is outside the ring, leading to 'black holing' of data packets.

Innovation Solution

Extending ERP to include a Media Access Control (MAC)-flush mechanism that reroutes data packets to a standby border router without activating the Ring Protection Link (RPL), even in the absence of a link failure within the Ethernet Ring, ensuring continuous data flow by updating MAC addresses and forwarding paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing ERP protocols are used to block the RPL under normal conditions, then loop avoidance is achieved, but data traffic loss occurs when link failures happen outside the ring

Engineering Contradiction:

Improvedata traffic continuityVSAvoidERP protocol complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring the standby border router and establishing backup forwarding paths before failures occur. When a link failure is detected, the system can immediately switch to the pre-prepared standby path without complex real-time calculations, thus maintaining data traffic continuity while managing protocol complexity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism (MAC-flush operation) that acts as a mediator between the failure detection and traffic rerouting processes. This intermediary triggers a controlled MAC address table flush that enables seamless transition to standby paths without requiring complex protocol modifications or activating the RPL

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the RPL is activated to reroute traffic around ring failures, then traffic continuity is maintained, but data packets are black-holed when failures occur outside the ring

Engineering Contradiction:

Improvetraffic rerouting capabilityVSAvoiddata packet loss

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent applies inversion by reversing the traditional approach: instead of activating the RPL to handle failures, the system flushes MAC address tables to enable traffic to be rerouted through standby border routers. This inverted approach prevents packet black-holing by ensuring packets are redirected through alternative paths rather than being trapped by RPL activation

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the operational parameter from RPL activation to MAC-flush operation. By changing the state of MAC address tables through the flush operation, the system enables dynamic rerouting of data packets to standby border routers, maintaining reliability while avoiding the harmful effect of packet loss associated with traditional RPL activation

Inventive Principle:

Principle #35Parameter changes

3Reliability

If MAC addresses are updated to reroute packets to standby border router, then data traffic loss is prevented, but network convergence time increases

Engineering Contradiction:

Improvedata traffic continuityVSAvoidnetwork convergence time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies periodic action through the MAC-flush operation that periodically updates MAC address tables in a controlled manner. This periodic refresh mechanism ensures that routing information is current while maintaining data traffic continuity, managing the trade-off between reliability and convergence time by using structured, time-managed updates

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS9979632B2Avoiding data traffic loss in a ring multihomed, in an active-standby manner, to a transport network

Publication Date: 2018.05.22 JUNIPER NETWORKS INC

AI summary

Data traffic loss in a an Ethernet Ring that is multihomed, in an active-standby manner, to a VPLS transport network (such as a Border Gateway Protocol (BGP) multihomed Ethernet Ring, an MC-LAG multihomed Ethernet Ring, or some other type of active-standby multihomed Ethernet Ring, etc.) (ring) is avoided. The exemplary multihomed ring running Ethernet Ring Protection (ERP) protocol includes a Ring Protection Link (RPL), a first node and a second node linked with a designated border router and a standby border router of the network, respectively. The data traffic loss in the multihomed ring is avoided by (i) receiving an indication that the link between the first node and the designated border router has failed; and (ii) invoking, responsive to the received indication, an ERP Media Access Control (MAC)-flush in the ring, even in the absence of a failed link in the ring and without activating the specified RPL. The ERP MAC-flush causes subsequent data packets from each of the plurality of nodes in the ring to be forwarded to the standby border router via the second node.