L2 Switch Session Redundancy via Upstream Copying

Solution Overview

Problem

In a network with redundant L2 switches, if a failure occurs in the master L2 switch, downstream communication is disrupted due to the lack of session information in the slave switch, leading to session interruptions and packet drops.

Innovation Solution

An L2 switch configuration that includes a receiving unit for copying upstream communication, an apparatus specifying unit to identify the transmission source based on MAC addresses, a session information processing unit to store and update session information, and a transferring unit to route downstream communication to the correct network apparatus using the stored information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a master L2 switch is used to manage session information for upstream communication, then the system achieves centralized control and proper session management, but the system lacks redundancy and becomes vulnerable to single points of failure

Engineering Contradiction:

Improvesession continuityVSAvoidswitch configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The slave L2 switch performs preliminary actions by receiving and storing copies of upstream communication packets and their session information in advance. When the master switch fails, the slave switch already has the necessary session information ready to immediately take over without interruption to downstream communication.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The slave L2 switch creates and stores copies of upstream communication packets and their associated session information. These copies enable the slave switch to function as a backup, maintaining session continuity if the master switch fails without requiring complex real-time synchronization mechanisms.

Inventive Principle:

Principle #26Copying

2Reliability

If session information is stored only in the master L2 switch, then the system maintains simple data management, but the slave L2 switch cannot handle downstream communication when the master fails

Engineering Contradiction:

Improvefailover capabilityVSAvoidsession information availability

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The slave L2 switch performs preliminary actions by receiving and storing copies of upstream communication packets and their session information in advance. When the master switch fails, the slave switch already has the necessary session information ready to immediately take over without interruption to downstream communication.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The slave L2 switch prepares backup session information in advance by storing copies of upstream communication packets. This beforehand cushioning ensures that when the master switch fails, the slave switch can immediately provide failover capability without loss of session information or communication interruption.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If the slave L2 switch does not store session information, then the system maintains simple storage requirements, but downstream communication is interrupted when the master L2 switch fails

Engineering Contradiction:

Improvecommunication continuityVSAvoidstored data volume

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The slave L2 switch performs preliminary actions by receiving and storing copies of upstream communication packets and their session information in advance. When the master switch fails, the slave switch already has the necessary session information ready to immediately take over without interruption to downstream communication.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11936490B2L2 switch, communication method, and communication program

Publication Date: 2024.03.19 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

Upon receiving a copy of upstream communication from a first switch, a second switch specifies an NF apparatus serving as a transmission source of the upstream communication, based on apparatus information indicating a MAC address of each apparatus and a transmission source MAC address contained in the copy of the upstream communication. The second switch refers to the apparatus information, and MAC address information indicating, for each port of the switch, a MAC address of an apparatus connected via the port, thereby specifying a port of the second switch connected to the NF apparatus, and a MAC address of the transmission source via the port. The second switch stores session information in which information on the specified port and MAC address is associated with header information set for the copy of the upstream communication. Upon receiving downstream communication, the second switch transfers the downstream communication to the NF apparatus.