End-to-End Flow Control for Packet Transmission Networks
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Solution Overview
Problem
Existing flow control methods in packet transmission networks, such as those defined by IEEE, fail to provide separate flow control for each piece of end-to-end traffic, leading to temporary cessation of all traffic on a physical link when congestion occurs, and prioritize flow control is limited, stopping all traffic with the same priority, which affects quality of service and efficiency.
Innovation Solution
A transmission device with a reception buffer that generates and transmits a control signal to stop data transmission when the buffer exceeds a threshold, specifically targeting end-to-end traffic, allowing for independent flow control of each traffic stream by designating end points for congestion management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flow control is performed in units of physical ports as defined in IEEE 802.3, then the flow control can be implemented simply by transmitting pause frames in units of physical links, but transmission of all traffic within the same physical link is temporarily stopped when congestion has occurred in certain traffic, resulting in loss of traffic differentiation
Solution Approach 1:
The invention segments the flow control mechanism from physical link level to traffic flow level by introducing virtual channel identifiers (VCIs) and destination identifiers (DIs). Instead of controlling all traffic on a physical link uniformly, the pause frames are segmented to target specific traffic flows identified by their unique DI-VCI combinations, enabling selective flow control while maintaining simple pause frame transmission mechanics
Solution Approach 2:
The invention applies local quality by assigning different flow control characteristics to different traffic flows on the same physical link. Each traffic flow is identified by a unique destination identifier and virtual channel identifier combination, allowing the reception device to apply pause frames selectively to specific traffic flows rather than uniformly to all traffic on the physical link
2Reliability
If priority flow control is implemented as flow control for every 8 priorities according to IEEE 802.1Qbb, then quality of service can be secured, but transmission of all traffic belonging to the same priority is temporarily stopped when congestion has occurred in certain traffic, resulting in unnecessary traffic cessation
Solution Approach 1:
The invention further segments flow control from priority level to individual traffic flow level by introducing destination identifiers in addition to priority levels. This allows the system to apply pause frames to specific traffic flows within a priority group rather than stopping all traffic of the same priority, thereby maintaining QoS while avoiding unnecessary traffic cessation
Solution Approach 2:
The invention applies local quality by enabling different flow control actions for different traffic flows within the same priority group. Each traffic flow is uniquely identified by a combination of priority level and destination identifier, allowing selective application of pause frames to only the congested traffic flow while other flows of the same priority continue uninterrupted
3Ease of manufacture
If priority flow control is performed as control in units of hops, then the control mechanism is simple to implement, but separate flow control for traffic between end points is not implemented, resulting in inability to perform end-to-end flow control
Solution Approach 1:
The invention makes the destination identifier field multi-functional by using it both for end-to-end traffic identification and for flow control target specification. The same DI field that identifies the ultimate destination is also used to identify which traffic flow should be targeted by pause frames, enabling end-to-end flow control without requiring separate control mechanisms for each hop
Data Source
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AI summary
Flow control can be performed for every piece of end-to-end traffic. A transmission device includes a reception buffer which temporarily accumulates received transmission unit data, a signal generation section configured to generate a control signal for instructing to stop transmission of transmission unit data by designating another transmission device serving as an end point of a transmission side for traffic of the transmission unit data to be received by its own device as a transmission destination when an amount of accumulation in the reception buffer has exceeded a predetermined upper-limit threshold value, and a transmission section configured to transmit the control signal.