Ethernet Link Active Status During LAN Interface Reset
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Solution Overview
Problem
Ethernet link resets disrupt user work by causing link downtime, as existing methods require resetting the Physical Layer, leading to inactive link status and additional procedures to reestablish the connection, which can be time-consuming and inconvenient.
Innovation Solution
Implementing a method to pause the Ethernet link instead of resetting it, allowing the Physical Layer to remain active during reconfiguration, using 'Pause' packets and data center bridging to manage traffic flow and buffer incoming data, while separating MAC and PHY resets to maintain link continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PHY is reset during Ethernet device reconfiguration, then the device can be reconfigured cleanly, but the link goes down and remains inactive for several seconds
Solution Approach 1:
The patent segments the reset operation into two independent parts: MAC reset and PHY reset. By resetting only the MAC layer while keeping the PHY layer active, the link remains up during reconfiguration. The PHY continues to process signals and maintain link synchronization, while the MAC is reset to achieve clean configuration state.
Solution Approach 2:
The patent extracts the necessary reset function from the PHY layer and applies it only to the MAC layer. This selective resetting removes the harmful effect of link downtime while preserving the beneficial effect of clean configuration. The PHY layer is taken out of the reset operation entirely, allowing it to continue functioning independently.
2Reliability
If the link is taken down during reset, then traffic interruption is avoided, but additional procedures like Auto Negotiation must be repeated
Solution Approach 1:
The patent segments the link functionality into independent MAC and PHY layers. The PHY layer maintains link continuity and handles physical signal processing, while the MAC layer is reset separately. This segmentation allows the link to remain up without requiring complex reconnection procedures like Auto Negotiation, as the PHY layer continues to maintain synchronization.
3Loss of time
If the MAC is reset while the link remains active, then link downtime is minimized, but incoming data must be buffered during reconfiguration
Solution Approach 1:
The patent introduces a buffering mechanism as an intermediary between the PHY layer and MAC layer. The buffer temporarily stores incoming data when the MAC is unavailable, allowing the link to remain active. This intermediary component resolves the conflict between maintaining link availability and handling MAC unavailability during reset.
4Ease of operation
If software treats link loss as far end reset, then connection management is simplified, but TCP connections are unnecessarily interrupted
Solution Approach 1:
The patent extracts the link status notification function from the physical link state and moves it to the MAC layer state. By keeping the link active at the PHY level while resetting only the MAC, the system avoids triggering software link-down handlers that would unnecessarily interrupt TCP connections. The connection stability is preserved while still allowing MAC reconfiguration.
Data Source
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AI summary
Methods and apparatus for supporting active link status during LAN interface reset and reconfigurations. Under one method, in response to a link reset event, transmit (TX) queues for a NIC are suspended and the TX pipe is drained. A PHY "Pause" packet is sent to a link partner for the NIC, and the NIC waits for an Ack to the Pause packet and for its receive (RX) pipe to drain. A link pause status is reported to software (e.g., an operating system or NIC device driver), which informs the software not to take the link down. The (re)configuration update process is performed, and information indicating the pause has ended is reported to the link partner and the software.