Multicast Port Adaptation in RSTP Ring Networks

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Solution Overview

Problem

The RSTP ring network hampers the development of broadband video services due to issues with IGMP REPORT packet transmission and source port checking, leading to potential loss of video streams and unauthorized multicast packets, especially when the port used for communication changes dynamically.

Innovation Solution

Implementing a method where access equipment configures corresponding ports for multicast programs to fixed, root port binding, or querier port following modes, updating ports when changes occur, and using a combination of ingress port, source IP, and multicast IP for strict packet validation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If IGMP REPORT packet is transmitted on a fixed port in RSTP ring network, then the multicast service can be maintained, but when the root port changes dynamically, the IGMP REPORT packet may be transmitted on the wrong link causing video stream loss

Engineering Contradiction:

Improvemulticast service reliabilityVSAvoidport change adaptability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the IGMP REPORT transmission port dynamic rather than fixed. The access equipment dynamically selects the transmission port based on the current root port status in the RSTP ring network, ensuring that IGMP REPORT packets are always sent through the active path to the aggregation equipment, thus adapting to port changes while maintaining multicast service reliability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback mechanisms where the access equipment continuously monitors the root port status and IGMP query responses from the aggregation equipment. Based on this feedback, the access equipment adjusts the IGMP REPORT transmission port to match the current active path, ensuring reliable multicast service even when network topology changes

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If source port checking is performed on multicast packets, then unauthorized packets can be blocked, but when the ingress port changes dynamically, normal video packets may be incorrectly discarded

Engineering Contradiction:

Improveunauthorized packet blockingVSAvoidvideo stream delivery reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies dynamics by making the source port checking mechanism adaptive to dynamic port changes. Instead of using a fixed source port in the multicast forwarding table, the system dynamically updates the source port based on the current root port status, ensuring that normal video packets are accepted while still blocking unauthorized packets

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by continuously monitoring the root port status and updating the source port in the multicast forwarding table accordingly. This feedback mechanism ensures that the source port checking remains synchronized with the actual network path, preventing false rejection of legitimate video packets while maintaining security

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If IGMP REPORT packet is transmitted to all uplink ports to avoid link availability issues, then link adaptation is improved, but other equipment may receive unnecessary packets and CPU processing burden increases

Engineering Contradiction:

Improvelink availability adaptationVSAvoidCPU processing burden

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent extracts the unnecessary action of transmitting IGMP REPORT packets to all uplink ports. Instead, it selectively transmits the IGMP REPORT packet only through the current root port, which is the active path to the aggregation equipment. This eliminates wasted transmission and reduces CPU processing burden on other equipment while maintaining link availability adaptation

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8045487B2Method for implementing multicast in rapid spanning tree protocol ring network

Publication Date: 2011.10.25 KONINKLIJKE PHILIPS NV

AI summary

The present invention discloses a method for implementing multicast in RSTP (Rapid Spanning Tree Protocol) ring network. In the method, the port mode of a program is configured to a fixed port mode, a root port binding mode or an upper layer querier port following mode; a multicast module on access equipment traverses a program table on receiving a root port switching message, updates the corresponding port of each program whose mode is configured to the root port binding mode as the changed root port; or on receiving an IGMP (Internet Group Management Protocol) QUERY packet from a port which is different from a recorded global querier port, the multicast module updates the global querier port as the port receiving the IGMP QUERY packet, traverses the program table, and updates the corresponding port of each program whose mode is configured to the upper layer querier port following mode as the port receiving the IGMP QUERY packet.