Multicast Flow Switch-Over via Packet Timestamp Extraction
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Solution Overview
Problem
Existing communication networks face challenges in synchronously switching over multicast flows, particularly in media production and IPTV applications, leading to visible glitches and artifacts due to unsynchronized client group modifications during video frame transitions.
Innovation Solution
A network device with packet processing circuitry that extracts a switch-over time value from packets, such as RTP timestamps, to simultaneously switch over multicast flows from one configuration to another at a video-frame boundary, ensuring system-wide synchronization without requiring time synchronization between network devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multicast flow switch-over is performed without synchronization, then network configuration changes can be applied flexibly, but visible glitches and artifacts occur due to unsynchronized client group modifications during video frame transitions
Solution Approach 1:
The system performs preliminary actions by extracting the switch-over time value from packet fields (such as RTP timestamps) before the actual switch-over occurs. This allows the network device to prepare and schedule the configuration change at the precise moment needed, ensuring synchronization with video frame boundaries without requiring complex real-time coordination between multiple devices.
Solution Approach 2:
Each network device independently extracts the switch-over time value from incoming packets and autonomously determines when to perform the switch-over. This self-service approach eliminates the need for centralized synchronization or complex inter-device communication, as each device uses the timestamp information already present in the packets to trigger the configuration change at the appropriate moment.
2Ease of manufacture
If switch-over time is extracted from a single selected multicast flow, then implementation is simplified, but time synchronization with other network devices cannot be guaranteed
Solution Approach 1:
The invention applies universality by using the switch-over time value extracted from a single multicast flow to control the switch-over of all multicast flows. This single timestamp value serves as a universal reference that coordinates switch-over across multiple flows and network devices, achieving system-wide synchronization without requiring individual timestamp extraction from each flow.
Solution Approach 2:
The patent introduces an intermediary approach by using the extracted switch-over time value as a mediator between different network devices and multicast flows. This timestamp value acts as a common reference point that enables coordination without direct interaction between devices, allowing each device to independently but synchronously perform the switch-over operation.
3Reliability
If multicast configurations are switched over simultaneously at video-frame boundaries, then glitches and artifacts are minimized, but bandwidth usage may be optimized differently
Solution Approach 1:
The system changes the timing parameter of configuration switch-over to occur at video-frame boundaries rather than at arbitrary moments. By aligning the switch-over with natural video frame transitions, the system minimizes visual glitches while maintaining efficient bandwidth usage, as the configuration change is made at a time when video data is naturally being transmitted.
Data Source
AI summary
A network device includes multiple ports, for communicating over a communication network, and packet processing circuitry. The packet processing circuitry is configured to receive via the ports packets belonging to a plurality of multicast flows, to receive, for each of the multicast flows, (i) a first configuration that specifies clients that are to receive the multicast flow prior to a specified switch-over time, and (ii) a second configuration that specifies the clients that are to receive the multicast flow after the specified switch-over time, to forward the multicast flows via the ports in accordance with the first configuration, to extract from a field in at least one of the packets a value that is indicative of the switch-over time, and, based on the extracted value, to switch-over forwarding of the multicast flows from the first configuration to the second configuration simultaneously at the switch-over time.