Link Interruption Signal for Dynamic PHY Speed Changes
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Solution Overview
Problem
In Ethernet systems, dynamic changes to link speed by physical layer devices (PHYs) often result in hard link down events, causing frame drops and requiring link restarts, which adversely affect the status seen by media access controllers (MACs).
Innovation Solution
The use of a link interruption signal transmitted by the PHY to the MAC facilitates dynamic changes in link speed without triggering link restart protocols, allowing the MAC to buffer frames and maintain link status, enabling advanced and dynamic PHY capabilities without disrupting upper layer protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic changes to link speed are performed by PHYs, then adaptability and link optimization are improved, but link stability deteriorates due to hard link down events and frame drops
Solution Approach 1:
The PHY asserts the link interruption signal before performing dynamic link speed changes or reconfigurations. This preliminary action prepares the MAC to buffer incoming frames, preventing frame drops during the transition. The link interruption signal is asserted in advance of the actual link parameter change, ensuring the MAC is ready to handle the interruption without losing data.
Solution Approach 2:
The link interruption signal serves as an intermediary mechanism between the PHY and MAC layers. It communicates the impending link interruption to the MAC, allowing the MAC to take appropriate buffering actions. This intermediary signal bridges the gap between PHY's dynamic capabilities and MAC's need for stable link status, enabling seamless transitions without frame drops.
2Reliability
If extensive buffering is implemented in PHY to prevent frame drops, then link reliability is improved, but device complexity increases
Solution Approach 1:
The buffering function is extracted from the PHY and relocated to the MAC layer. Instead of implementing extensive buffering in the PHY to prevent frame drops, the invention uses the link interruption signal to prompt the MAC to perform the buffering. This extraction reduces PHY complexity while maintaining frame drop prevention capability.
Solution Approach 2:
The MAC layer serves itself by buffering frames in response to the link interruption signal from the PHY. Rather than requiring the PHY to provide complex buffering services, the MAC autonomously handles frame buffering when notified of impending link interruptions, simplifying the PHY's design and reducing its buffering requirements.
3Adaptability or versatility
If link restart protocols are triggered during dynamic changes, then link adaptability is improved, but loss of time increases due to link restart overhead
Solution Approach 1:
The link interruption signal is asserted in advance of the link reconfiguration, allowing the MAC to buffer frames before the actual change occurs. This preliminary notification prevents the need for link restart protocols, as the MAC is already prepared to handle the interruption. The dynamic change can proceed without triggering time-consuming link restart sequences.
Solution Approach 2:
By using the link interruption signal to prepare the MAC beforehand, the useful action of data transmission continues uninterrupted during the link reconfiguration. The MAC buffers frames during the transition, ensuring continuous data flow without gaps caused by link restarts. This maintains the continuity of useful action despite the underlying link parameter changes.
Data Source
AI summary
Advanced and dynamic physical layer device capabilities utilizing a link interruption signal. The physical layer device can use a link interruption signal to signal to a media access controller device that the link has temporarily been interrupted. This link interruption signal can be generated in response to one or more programmable modes of the physical layer device that are used to support the advanced and dynamic physical layer device capabilities.