Multicast Switchover Signaling for Packet Loss Prevention
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Solution Overview
Problem
The existing techniques for switching from a default multicast distribution tree (MDT) to a data MDT in networking are unreliable, leading to potential packet loss as the head-end router may switch before confirming that all interested receivers have joined the data MDT, resulting in receivers not receiving the multicast stream.
Innovation Solution
Implementing reliable signaling protocols, such as TCP or BGP, to ensure that all egress routers respond to the switchover message before proceeding, and using a data MDT building method that confirms all interested receivers have joined before switching from the default MDT to the data MDT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the head-end router sends a switchover message to PE routers indicating a switch from default MDT to data MDT, then the multicast stream can be offloaded to specific receivers, but some PE routers may not receive the message resulting in packet loss
Solution Approach 1:
The patent applies preliminary action by requiring PE routers to send join requests to join the data MDT before the head-end router performs the switchover. This ensures that the data MDT is pre-established and ready to receive multicast traffic before the switch occurs, preventing packet loss. The head-end router waits for confirmation that all necessary PE routers have joined the data MDT before initiating the switchover from the default MDT.
2Reliability
If the head-end router waits for confirmation from all PE routers before switching, then packet loss is prevented, but the switchover process becomes complex and time-consuming
Solution Approach 1:
The patent implements feedback by having PE routers send join requests and the head-end router tracking these requests to determine when all necessary routers have joined the data MDT. This feedback mechanism provides the head-end router with the information needed to safely perform the switchover without packet loss, while maintaining a manageable level of complexity through systematic tracking and confirmation processes.
3Reliability
If all PE routers are required to join the data MDT before switchover, then interested receivers receive the stream reliably, but uninterested receivers continue to receive data through the default MDT
Solution Approach 1:
The patent applies dynamics by making the data MDT construction a dynamic, receiver-driven process. PE routers send join requests based on their local receivers' interest in the multicast stream. The head-end router dynamically constructs the data MDT by adding PE routers as they send join requests, rather than requiring all PE routers to join in advance. This dynamic approach ensures reliable delivery to interested receivers while avoiding waste of network bandwidth to uninterested receivers.
Data Source
AI summary
Techniques reliably provide the switchover from a default MDT to the data MDT by using reliable signaling and reliable building of a data MDT. The message notifying of the pending switchover to the data MDT is reliably sent using signaling that is reliable. Also, the switchover from the default MDT to the data MDT does not happen until all egress routers have responded to the message. Egress routers join the data MDT if associated receivers are interested in receiving the multicast stream from a source. The router does not send another response upstream until all egress routers downstream from it respond to the message in the positive or the negative.