Ethernet Switch PFCC Congestion Control Across VLANs
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Solution Overview
Problem
Current Ethernet flow control mechanisms, such as PFC and QCN, are inadequate in addressing congestion across multiple VLANs and fail to effectively manage both ingress and egress queue congestion, leading to network blocking issues and packet loss.
Innovation Solution
The proposed solution, Priority Flow and Congestion Control (PFCC), involves an Ethernet switch that detects egress congestion, identifies contributing ingress link partners, and propagates flow control messages across VLAN boundaries using IEEE 802.1Qbb pause frames, combining ingress and egress congestion states to prevent head-of-line blocking and ensure lossless services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional PFC is used for flow control, then ingress queue congestion can be managed, but egress queue congestion cannot be effectively addressed
Solution Approach 1:
The patent segments the flow control mechanism into separate ingress and egress queue congestion state determinations. The ingress queue congestion state is determined based on ingress buffer usage, while the egress queue congestion state is determined based on egress buffer usage. This segmentation allows independent monitoring and control of congestion at both ingress and egress points, resolving the limitation of traditional PFC that only addressed ingress congestion.
Solution Approach 2:
The patent extends flow control from a single-dimensional ingress-only approach to a two-dimensional approach by adding egress queue congestion detection and control. The flow control state is determined by combining both ingress and egress congestion states, creating a comprehensive control mechanism that operates across multiple dimensions of queue management and VLAN boundaries.
2Adaptability or versatility
If flow control messages are propagated across VLAN boundaries, then multi-VLAN congestion can be managed, but network complexity increases
Solution Approach 1:
The patent implements a universal flow control mechanism that operates across VLAN boundaries by treating all VLANs uniformly. The same congestion detection, state determination, and message propagation logic applies regardless of VLAN configuration. This multi-functional approach allows a single control mechanism to handle both intra-VLAN and inter-VLAN congestion scenarios, reducing the need for separate complex control logic for different VLAN configurations.
3Reliability
If both ingress and egress congestion states are combined, then head-of-line blocking is prevented, but control logic complexity increases
Solution Approach 1:
The patent merges the ingress queue congestion state and egress queue congestion state to determine the overall flow control state. Both states are considered simultaneously, and the flow control message is transmitted only when both ingress and egress queues are in a congested state. This merging approach ensures comprehensive congestion control while preventing head-of-line blocking, as packets are only paused when both ingress and egress conditions warrant it.
Data Source
AI summary
An apparatus is configured to perform a method for congestion control in an Ethernet network. The method includes determining an egress queue congestion state for each of a plurality of egress queues. The method also includes determining an ingress queue congestion state for each of a plurality of ingress queues. The method further includes determining a flow control state for at least one of the ingress queues based on the determined egress queue congestion states and ingress queue congestion states. In addition, the method includes transmitting a flow control message to the at least one ingress queue based on the determined flow control state.