SCTP Flow Control for Satellite Links
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Solution Overview
Problem
Stream Control Transmission Protocol (SCTP) flow control mechanisms, inherited from Transmission Control Protocol (TCP), face limitations in managing congestion across long pipes like satellite links, leading to suboptimal performance due to inadequate adjustment of unacknowledged data transmission.
Innovation Solution
Implementing a flow control scheme that sets a maximum congestion window proportional to the available bandwidth and round trip time, with exponential and linear increases based on acknowledgement thresholds, to prevent packet loss and optimize data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional TCP flow control is used, then basic flow control is achieved, but performance is suboptimal on long pipes like satellite links
Solution Approach 1:
The patent applies dynamics by making the congestion window size adjustable and adaptive rather than fixed. The flow control mechanism dynamically modifies the congestion window based on feedback about network conditions, allowing optimal performance on long pipes like satellite links where traditional static TCP flow control fails.
Solution Approach 2:
The patent changes the parameter of congestion window size from a fixed value to a variable that can be adjusted based on network conditions. By modifying this key parameter dynamically, the system achieves better flow control performance and productivity on long-distance communications.
2Reliability
If SCTP flow control is used, then some improvements over TCP are achieved, but limited improvement is realized
Solution Approach 1:
The patent implements feedback by monitoring network conditions and using this information to adjust the congestion window size. This feedback mechanism allows the system to learn from past performance and optimize future data transmission, achieving significant improvement in both reliability and productivity.
Solution Approach 2:
The flow control mechanism performs self-service by automatically adjusting its own parameters based on observed network behavior. The system monitors its own performance and makes self corrections to optimize data transmission without external intervention, realizing substantial improvements over traditional SCTP flow control.
3Productivity
If congestion window is increased to improve transmission speed, then productivity increases, but packet loss due to congestion occurs
Solution Approach 1:
The patent uses feedback to monitor network congestion levels and adjusts the congestion window size accordingly. When signs of congestion are detected, the system reduces the window size to prevent packet loss. When the network is clear, it increases the window to maximize transmission speed, thus balancing productivity and reliability.
Solution Approach 2:
The system dynamically adjusts the congestion window size based on real-time network conditions rather than using a fixed large value. This dynamic adaptation allows the system to maximize transmission speed when possible while preventing packet loss through careful, condition-based adjustment of the window size.
Data Source
AI summary
Described herein is a flow control scheme suitably adaptable to Transmission Control Protocol (TCP) and Stream Control Transmission Protocol (SCTP). In an example embodiment, the guaranteed and maximum allowable bandwidths are employed to determine the size of the congestion window. For example, the flow congestion window size starts proportional to the guaranteed bandwidth and increases until reaching the maximum allowable bandwidth. In particular embodiments, a fixed value is used for determining how fast the congestion window increases. For example the congestion window may increase exponentially while the current size of the congestion window is at or below a fixed value, and increase linearly when the current size of the congestion window is above the fixed value. In an example embodiment, the fixed value does not change even if a collision is detected and the current amount of unacknowledged data allowed is reset to an initial value.