Hierarchical Policer for Multiplex Network Receive Queue Fairness
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Solution Overview
Problem
In the producer-consumer software model, shared queues lead to fairness issues where heavy producers dominate access to the queue, excluding light producers, and existing solutions fail to provide adequate fairness, especially in network environments where congestion control is not always necessary.
Innovation Solution
A hierarchical policer system with two levels of meters and three label types (type-1, type-2, type-3) is implemented to manage packet access to a multiplex network receive queue, ensuring each network flow has minimal access by labeling and relabeling packets based on available credits, with type-3 packets being dropped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If a shared queue is provided for multiple producers and consumers, then the memory footprint is reduced, but queue fairness is compromised as heavy producers exclude light producers
Solution Approach 1:
The patent segments the packet processing into multiple stages by introducing a hierarchical policer with two levels (level-1 and level-2 meters). Each level performs specific functions: level-1 meters perform initial packet marking based on flow classification, while level-2 meters perform final admission control. This segmentation allows the system to manage queue access rights in a structured manner, ensuring fairness while sharing the queue resource.
Solution Approach 2:
The patent introduces an intermediary mechanism - the hierarchical policer - that sits between the network interface and the receive queue. This intermediary uses packet marking and credit-based admission control to mediate access to the shared queue. The policer marks packets with different identifiers and uses credit counters to control which marked packets are admitted to the queue, thereby enforcing fairness policies without requiring separate queues for each flow.
2Reliability
If separate queues are provided for each producer-consumer pair, then queue fairness is ensured, but the memory footprint grows linearly with the number of consumers
Solution Approach 1:
The patent merges multiple separate queues into a single shared receive queue by using the hierarchical policer to manage access rights. Instead of allocating dedicated queues for each producer-consumer pair, the system combines all flows into one queue and uses the policer's marking and admission control mechanisms to ensure fair access. This merging approach maintains fairness while significantly reducing memory consumption.
3Reliability
If a hierarchical policer with two levels of meters is implemented, then queue fairness is provided, but device complexity increases
Solution Approach 1:
The hierarchical policer is segmented into two functional levels: level-1 meters for packet marking and level-2 meters for admission control. This segmentation allows each level to perform its specific function efficiently, with level-1 handling the bulk of packet marking and level-2 handling final admission decisions. The modular structure makes the complex system more manageable and implementable.
Solution Approach 2:
The patent applies partial action by having level-1 meters perform initial marking of packets that may need special handling, while level-2 meters perform the complete admission control. Not all packets need to go through both levels - the system can be configured to admit certain marked packets directly without level-2 processing. This partial processing approach reduces the effective complexity while maintaining fairness.
Data Source
AI summary
In one embodiment, a network device, including a network interface to receive packets over a packet data network, and a hierarchical policer to provide queue fairness for a plurality of network flows competing for access to a multiplex network receive queue, and including level one meters to label the received packets, a level two meter to receive at least some of the labeled packets and relabel the at least some labeled packets, and queueing logic add the packets labeled with a first label-type to the multiplex network receive queue and drop the packets labeled with a third label-type.