RDMA Message Log for Multicast Data Distribution
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Solution Overview
Problem
Multicast data transport in communication systems faces issues such as significant overhead, unnecessary data delivery, latency, and dependency on the publisher for active data delivery and acknowledgment, leading to inefficiencies and potential data loss.
Innovation Solution
A data publisher system that allocates a memory area for Remote Direct Memory Access (RDMA) operations, allowing subscribers to independently read messages stored in a message log using a multicast transport protocol, with headers containing sequence numbers and virtual memory addresses, enabling efficient message retrieval and reducing dependency on the publisher for data delivery and acknowledgment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multicast data transport is used to distribute data to multiple subscribers, then data distribution capability is improved, but overhead at the publisher side increases significantly
Solution Approach 1:
The patent extracts the reliability assurance function from the publisher side and moves it to the subscriber side. Subscribers independently verify message receipt using sequence numbers and autonomously request retransmissions, eliminating the publisher's need to manage complex acknowledgment and retransmission protocols for multiple subscribers.
Solution Approach 2:
Subscribers perform self-service by autonomously detecting missing messages through sequence number verification and independently requesting retransmissions. This self-service mechanism eliminates the need for publisher-side management of delivery reliability, reducing publisher overhead while maintaining data distribution capability.
2Reliability
If reliable data delivery mechanisms are implemented using additional protocol layers, then data delivery reliability is improved, but fabric utilization increases and multicast storms occur
Solution Approach 1:
The patent extracts the reliability management function from the network fabric and protocol layers and places it at the application layer on the subscriber side. Subscribers use sequence numbers to detect missing messages and request retransmissions directly from the publisher, eliminating the need for complex reliable transport protocol layers that consume fabric resources.
Solution Approach 2:
Instead of implementing comprehensive reliable delivery protocols for all messages, the patent uses selective retransmission based on sequence number verification. Subscribers request only the specific missing messages they need, avoiding the excessive fabric utilization that would result from blanket retransmission mechanisms.
3Reliability
If active acknowledgment mechanisms are used for data delivery, then delivery confirmation is improved, but latency increases
Solution Approach 1:
Subscribers perform self-verification of message receipt using sequence numbers included in each message. This immediate local verification eliminates the need for round-trip acknowledgment messages, providing delivery confirmation without the latency penalty of active acknowledgment protocols.
4Stability of the object's composition
If synchronization schemes are implemented between publisher and subscribers, then coordinated data delivery is improved, but system complexity increases
Solution Approach 1:
The patent incorporates sequence numbers in preliminary action within each message packet, enabling subscribers to independently verify message order and detect missing messages without requiring complex synchronization protocols. This preliminary embedding of coordination information simplifies the overall system architecture.
Data Source
AI summary
Device, system, and method of distributing messages. For example, a data publisher capable of communication with a plurality of subscribers via a network fabric, the data publisher comprising: a memory allocator to allocate a memory area of a local memory unit of the data publisher to be accessible for Remote Direct Memory Access (RDMA) read operations by one or more of the subscribers; and a publisher application to create a message log in said memory area, to send a message to one or more of the subscribers using a multicast transport protocol, and to store in said memory area a copy of said message. A subscriber device handles recovery of lost messages by directly reading the lost messages from the message log of the data publisher using RDMA read operation(s).