Chassis Type Switch Line Card Failure Detection and Forced Flooding
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Solution Overview
Problem
Chassis type switches experience prolonged communication interruption due to the time required for switching over to a backup route after detecting a line card failure, with existing technologies taking several hundreds of milliseconds to complete the FDB flush and route switching.
Innovation Solution
Incorporating a failure detection unit and a forced flooding processing unit within each line card to quickly detect and respond to line card failures by forcibly changing the frame type in the intra-device transfer header, allowing unicast frames to be flooded to all ports and other line cards when a failure is detected, thereby enabling immediate switching to a backup route.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FDB flush is executed with software after detecting line card failure, then route switching is performed, but communication interruption lasts several hundreds of milliseconds
Solution Approach 1:
The patent replaces the software-based FDB flush mechanism with a hardware-based failure detection and frame flooding mechanism. Line cards use hardware circuits to detect failures of other line cards and automatically flood unicast frames to all ports when failures are detected, eliminating the software processing delay that caused hundreds of milliseconds of communication interruption.
Solution Approach 2:
The patent implements preliminary failure detection capabilities in each line card's hardware, allowing the system to detect failures and switch to backup routes before software-based FDB flush can be executed. This preliminary hardware-level detection and response mechanism reduces the overall failure recovery time significantly.
2Reliability
If FDB entries are erased with software to switch to backup route, then communication can be restored, but the process takes several hundreds of milliseconds
Solution Approach 1:
The patent substitutes the software-based FDB entry erasure process with a hardware-based frame flooding mechanism. When a line card detects a failure, its hardware circuit automatically floods unicast frames to all ports without requiring software intervention to erase FDB entries, thereby restoring communication much faster than the software-based approach.
Solution Approach 2:
Each line card is equipped with autonomous failure detection and frame flooding capabilities in hardware, allowing it to self-respond to failures of other line cards without requiring central controller intervention or software-based FDB flush operations. This self-service mechanism at the hardware level dramatically reduces the time required for communication restoration.
Data Source
AI summary
A chassis type switch is provided which can shorten a time required for switching-over to a backup route when a failure has occurred in a line card. In a chassis type switch including a plurality of line cards within a chassis, the switch further includes a failure detection unit for detecting a failure in each of the plural line cards, and a forced flooding processing unit included in each of the plural line cards and operating such that when, in trying to transfer a received unicast frame to another line card, a failure is detected in the relevant line card at a transfer destination, the received unicast frame is forcibly transferred to all ports of the own line card other than a reception port thereof and to all other line cards.