Packet Queue Admission Control for Priority-Based Drop Decisions
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Solution Overview
Problem
Existing congestion avoidance algorithms in packet networking do not consider the precedence of already queued frames when making drop decisions, leading to inefficient management of limited packet buffer resources.
Innovation Solution
Implementing queue admission control circuitry that discards already queued lower priority packets to make room for higher priority packets, using buffer reallocation to support higher priority frames and improve drop decisions during congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If congestion avoidance algorithms drop frames based on queue length thresholds, then queue buffer space is preserved for future arrivals, but higher priority frames may be dropped when lower priority frames occupy the queue
Solution Approach 1:
The patent applies local quality by treating different priority frames differently within the same queue. When a drop decision is needed, the system selectively drops lower priority frames while preserving higher priority frames, rather than applying a uniform drop policy. This is implemented by checking the priority of queued frames and making differentiated drop decisions based on priority levels.
Solution Approach 2:
The patent inverts the conventional drop decision logic. Instead of dropping higher priority frames to preserve buffer space (as in traditional WRED), the system drops lower priority frames first when buffer space needs to be freed. This inversion ensures that critical high-priority traffic is preserved while still managing buffer resources effectively.
2Quantity of substance
If packet buffers are shared among all ports and queues, then resource utilization is improved, but management complexity increases when congestion occurs
Solution Approach 1:
The patent applies preliminary action by pre-configuring drop precedence values for different frame types and priorities. When congestion is detected, the system can immediately execute drop decisions based on these pre-established rules without complex real-time calculations. The drop precedence information is prepared in advance, allowing rapid response to congestion while maintaining simple management logic.
3Ease of manufacture
If tail drop is used without considering frame priority, then implementation is simple, but higher priority frames are dropped along with lower priority frames
Solution Approach 1:
The patent extracts the priority consideration from the conventional tail drop mechanism. By introducing a separate drop precedence field that is independent of the basic tail drop logic, the system maintains the simplicity of tail drop while adding priority-awareness. The extraction allows the priority mechanism to be added without fundamentally changing the tail drop implementation, preserving ease of manufacture while improving QoS reliability.
Data Source
AI summary
A packet switch includes an ingress port; queue admission control circuitry connected to the ingress port; one or more egress queues configured to manage packet buffers; and an egress port connected to the packet buffers, wherein the packet buffers are managed such that already queued lower priority packets are discarded from the packet buffers when it is required to drop higher priority packets that should otherwise be accepted in the packet buffers. The queue admission control circuitry can be configured to determine if a packet should be dropped or not, and the queue admission control circuitry communicates to buffer reallocation circuitry that is configured to discard one or more lower priority packets to support enqueuing the higher priority packet.