Single Stage Switching Topology Packet Rate Limiting
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Solution Overview
Problem
Packet switching networks face challenges in managing congestion, leading to large reordering buffers due to unequal congestion in the fabric, which can cause buffer overflow and reduce network efficiency.
Innovation Solution
Implementing a method to distribute and rate-limit packets across multiple paths in a single stage switching topology, using a reordering node that stores packets in queues and sends them in original order, while requesting rate limiting from packet switching devices experiencing low queueing delay to alleviate buffer overflow through Priority-based Flow Control (PFC) messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If packets are distributed across multiple paths in a single stage switching topology, then load balancing and bandwidth are improved, but unequal congestion causes large reordering buffers and buffer overflow risk
Solution Approach 1:
The system performs preliminary rate limiting at the packet switching devices before packets reach the reordering node. By proactively controlling the packet transmission rate based on queueing delay feedback, the system prevents buffer overflow before it occurs, eliminating the need for large reordering buffers while maintaining high bandwidth utilization through multi-path distribution
Solution Approach 2:
The system implements a feedback mechanism where the reordering node monitors queueing delay at packet switching devices and sends rate limiting requests back to those devices. This closed-loop feedback allows dynamic adjustment of packet rates to balance load across multiple paths while preventing congestion that would require large buffers
2Reliability
If rate limiting is applied to packet switching devices with low queueing delay, then buffer overflow is prevented, but network efficiency may be reduced
Solution Approach 1:
The system dynamically adjusts rate limiting based on real-time queueing delay conditions. Rate limiting is applied selectively and temporarily only to packets from paths experiencing low queueing delay, allowing the system to adapt to changing network conditions and maintain high efficiency while preventing buffer overflow
Solution Approach 2:
The system changes the transmission rate parameter dynamically based on queueing delay measurements. By adjusting the packet rate parameter in response to monitored conditions, the system prevents buffer overflow while minimizing impact on overall network efficiency through selective and temporary rate adjustments
Data Source
AI summary
One embodiment includes multiple distribution nodes sending packets of different ordered sets of packets among multiple packet switching devices arranged in a single stage topology to reach a reordering node. The reordering node receives these packets sent over the different paths and stores them in reordering storage, such as, but not limited to, in queues for each distribution node and packet switching device combination. The reordering node sends packets stored in the reordering storage from the reordering node in original orderings. In response to determining that an aggregation quantum of packets received from the multiple distribution nodes via a particular packet switching device and stored in the reordering storage is outside a range or value, packets being communicated via the particular packet switching device to the reordering node are rate limited.