Network Flow Control Pre-empting Jumbo Frames
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Solution Overview
Problem
In complex network topologies, conventional flow control mechanisms often result in dropped packets due to insufficient buffer resources, leading to increased traffic and deadlocks, especially at switches, where a single busy port can cause multiple ports to pause transmission, amplifying the issue.
Innovation Solution
The approach involves pre-empting the transmission of Jumbo frames to immediately send flow control messages, reducing buffer size requirements by ensuring that entire Jumbo frames are buffered until transmission is complete, allowing for immediate abortion and retransmission of frames, and implementing a NACK feedback scheme to pause transmission at switches, enabling earlier detection of congestion and reducing packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flow control mechanisms are used, then flow control is maintained, but packet loss increases due to insufficient buffer resources
Solution Approach 1:
The patent applies preliminary action by pre-empting the transmission of Jumbo frames before buffer overflow occurs. The receiver sends flow control messages proactively to prevent the transmitter from sending frames that would overflow the buffer, thereby avoiding packet loss without requiring large buffer resources.
Solution Approach 2:
The patent implements feedback through flow control messages (PAUSE frames) that the receiver sends to the transmitter when buffer space is insufficient. This feedback mechanism allows the transmitter to adjust its transmission rate dynamically, preventing packet loss while maintaining efficient buffer usage.
2Reliability
If buffer size is increased to prevent packet loss, then packet loss decreases, but device complexity and resource consumption increase
Solution Approach 1:
Instead of increasing buffer size, the patent uses preliminary action by pre-empting Jumbo frame transmission before buffer overflow occurs. The flow control mechanism prevents the need for large buffers by stopping transmission in advance when buffer space is insufficient.
Solution Approach 2:
The patent applies dynamics by making the flow control mechanism adaptive and dynamic. The receiver dynamically adjusts transmission by sending flow control messages based on real-time buffer status, allowing the system to handle variable traffic conditions without requiring fixed large buffer allocations.
3Reliability
If flow control messages are sent immediately, then packet loss decreases, but transmission time is increased due to interruptions
Solution Approach 1:
The patent applies preliminary action by pre-empting Jumbo frame transmission before buffer overflow occurs. By sending flow control messages proactively, the system prevents packet loss while minimizing transmission interruptions, as frames are stopped only when necessary rather than continuously.
Solution Approach 2:
The patent maintains continuity of useful action by allowing normal transmission to proceed until buffer space is insufficient. Flow control messages are sent only when necessary to prevent overflow, minimizing interruptions to the overall transmission process while maintaining reliability.
4Speed
If Jumbo frames are transmitted without pre-emption, then transmission speed is maintained, but buffer overflow and packet discarding occur
Solution Approach 1:
The patent applies preliminary action by pre-empting Jumbo frame transmission before buffer overflow occurs. The receiver sends flow control messages to prevent the transmitter from sending frames that would overflow the buffer, thereby avoiding packet loss while maintaining transmission speed during normal operation.
Solution Approach 2:
The patent implements feedback through flow control messages that provide real-time information about buffer status to the transmitter. This feedback allows the transmission speed to be maintained during normal conditions while preventing buffer overflow when necessary, balancing speed and reliability.
Data Source
AI summary
Methods and apparatus for implementing flow control with reduced buffer usage for network devices. In response to detection of flow control events, transmission of a data unit or segment such as an Ethernet frame is preempted in favor of a flow control message, resulting in aborting transmission of the frame. Data corresponding to the entirety of the frame is buffered at the transmitting station until the frame has been transmitted (or after a delay), enabling retransmission of the aborted frame. Preemption of frames in favor of flow control messages results in earlier responses to flow control events, enabling the size of buffers to be reduced.