MAC Merge Sublayer Encapsulation for Link Layer Preemption
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Solution Overview
Problem
High-speed data networks face challenges in prioritizing packet transmission, where high-priority packets may need to interrupt low-priority packets in transit, requiring efficient methods to preempt and re-establish transmission without increasing errors or impacting throughput.
Innovation Solution
The implementation of a Media Access Control (MAC) merge sublayer that supports link layer preemption through encapsulation techniques, allowing high-priority packets to interrupt low-priority packets and resume transmission seamlessly, while maintaining data integrity and minimizing impact on network throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If link layer preemption is implemented to allow high-priority packets to interrupt low-priority packets, then latency for high-priority packets is reduced, but complexity of the network device increases
Solution Approach 1:
The packet transmission process is segmented into preemptible and non-preemptible portions. High-priority packets can preempt the initial portion of low-priority packet transmission, while the remaining portion continues separately. This segmentation allows latency reduction for high-priority traffic without requiring complete interruption and retransmission of low-priority packets, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent implements preliminary marking of packet portions as preemptible or non-preemptible before transmission begins. By pre-designating which portions can be interrupted, the system prepares the transmission structure in advance, enabling efficient preemption decisions without complex real-time analysis during transmission, thus reducing device complexity while maintaining low latency capability.
2Speed
If preemption is implemented without encapsulation, then high-priority packet transmission is accelerated, but error rate increases due to interrupted low-priority packets
Solution Approach 1:
An encapsulation layer is introduced as an intermediary between the preemption mechanism and the packet data. This encapsulation wraps packets with headers that identify preemptible and non-preemptible portions, allowing the preemption process to operate on structured data units rather than raw packets. This intermediary structure prevents errors by ensuring that preemption boundaries are clearly defined and properly handled, maintaining reliability while enabling high-speed preemption.
Solution Approach 2:
The patent changes the parameter structure of packets by adding encapsulation headers that specify preemption characteristics. These parameter changes include markers indicating which portions of packets can be preempted and which cannot. By modifying packet parameters rather than the fundamental transmission mechanism, the system achieves high-speed preemption while maintaining error rates at acceptable levels through proper parameter management.
3Reliability
If traditional encapsulation methods are used, then data integrity is maintained, but throughput is degraded due to overhead from retransmission protocols
Solution Approach 1:
The patent extracts the preemption control information from the traditional retransmission protocol overhead and implements it directly in the encapsulation layer. By taking out the preemption management function from higher-layer protocols and embedding it in the link layer encapsulation, the system maintains data integrity through proper tracking of preempted portions while eliminating redundant retransmission overhead, thereby improving throughput.
Data Source
AI summary
Devices implement encapsulation to support link layer preemption. The device may include a encapsulation logic that encapsulates data, such as an Ethernet frame, to produce an encapsulated frame. The encapsulated frame may include an encapsulation element that indicates whether the encapsulated data includes non-preemptible data, such as Distinguished Minimum Latency Traffic (DMLT), or preemptible data. The encapsulated frame may also indicate whether the encapsulated data comprises the last fragment of a preemptible frame.