Ethernet Egress Port Inter-Packet Gap Adjustment for Frequency Offset Compensation
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Solution Overview
Problem
Frequency offsets between ingress and egress local area networks in transport networks can lead to buffer overflow, especially in high-bandwidth conditions, where the egress network's buffer is unable to process packets at the same rate as the ingress network, resulting in data loss and congestion.
Innovation Solution
The solution involves adjusting the size of the inter-packet gap at the egress port to compensate for frequency offsets by reducing or increasing the number of bytes in the inter-packet gap, either statically or dynamically based on buffer levels, to maintain the egress buffer within a desired range and prevent overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the transmission rate of the ingress LAN is increased to meet bandwidth demands, then the data transmission speed is improved, but the egress buffer overflow risk increases
Solution Approach 1:
The patent applies dynamics by making the inter-packet gap adjustable rather than fixed. The egress station dynamically modifies the inter-packet gap size based on the frequency offset between ingress and egress LANs, allowing the system to adapt to varying transmission conditions and prevent buffer overflow while maintaining high transmission speeds
Solution Approach 2:
The patent changes the parameter of inter-packet gap size to compensate for frequency offsets. By adjusting this temporal parameter at the egress station, the system reconciles the timing differences between ingress and egress networks, enabling reliable data reception at high speeds without buffer overflow
2Reliability
If the inter-packet gap size is reduced at the egress port to compensate for frequency offset, then the buffer overflow is prevented, but the packet processing time increases
Solution Approach 1:
The patent applies partial action by adjusting only the inter-packet gap parameter specifically to compensate for frequency offsets, rather than fundamentally changing the entire packet processing mechanism. This targeted adjustment prevents buffer overflow while minimizing impact on overall packet processing time
3Reliability
If the egress station waits for packets to arrive at the correct frequency, then the frequency offset is compensated, but the data transmission delay increases
Solution Approach 1:
The patent applies preliminary action by having the egress station proactively adjust the inter-packet gap in anticipation of frequency offset issues, rather than reacting after packets arrive out of sync. This advance adjustment maintains frequency synchronization without causing significant transmission delays
Data Source
AI summary
A method and apparatus are disclosed for compensating for a frequency offset between an ingress local area network and an egress local area network that communicate over a transport network. The bandwidth of an egress port is adjusted by varying an inter-packet gap size between each packet so that the packets can be delivered without overflowing an egress buffer. The size of the inter-packet gap is reduced when the frequency of the ingress local area network is greater than the frequency of the egress local area network. The size of the inter-packet gap is increased when the frequency of the ingress local area network is less than the frequency of the egress local area network. The size of the egress inter-packet gap may be statically or dynamically adjusted to compensate for a frequency offset.