TCP Packet Zone Determination Using MSB Extraction
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Solution Overview
Problem
The computation of the midpoint in the TCP sequence space for determining whether a packet is in-zone or out-of-zone is computationally intensive due to the large size of TCP sequence numbers, leading to bottlenecks in processing incoming TCP packets and limiting effective throughput.
Innovation Solution
An anchor representing the TCP sequence number of the last data byte is updated, and a 33-bit test value is formed by adding 1 to the most significant bit of the anchor, which is then used to compare with the sequence number of the received packet to determine if it falls within the in-zone or out-of-zone range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional adder is employed to generate the relative midpoint, then the midpoint calculation is accurate, but the adder is large (33 bits) and requires substantial logic, increasing device complexity
Solution Approach 1:
The patent extracts only the necessary portion of the sequence number (the most significant bit) to determine the midpoint, rather than using the complete 32-bit sequence number in a full adder. This extraction approach reduces the adder size from 33 bits to a much smaller structure while maintaining sufficient precision for zone determination.
Solution Approach 2:
The patent segments the 32-bit sequence number into two parts: the most significant bit (MSB) and the remaining 31 bits. By using only the MSB for midpoint calculation and treating the remaining bits as offset values, the system achieves accurate zone determination with significantly reduced computational complexity and smaller adder size.
2Measurement precision
If the midpoint is computed for each packet, then the zone determination is accurate, but the computation becomes a bottleneck in processing incoming TCP packets, limiting throughput
Solution Approach 1:
The patent extracts only the most significant bit of the sequence number for midpoint calculation, dramatically reducing the computation required per packet. This extraction approach maintains accurate zone determination while eliminating the computational bottleneck that limited throughput.
Solution Approach 2:
The patent uses a partial action approach by computing only the necessary portion of the midpoint (based on MSB) rather than the complete midpoint value. This partial computation is sufficient for zone determination and significantly speeds up packet processing throughput.
3Productivity
If the TCP sequence space is divided into in-zone and out-of-zone ranges, then packet processing can be optimized, but the zone boundaries change with each packet, requiring dynamic midpoint calculation
Solution Approach 1:
The patent implements a dynamic approach where the zone boundaries adapt to each packet's sequence number. By using the MSB of the current sequence number to determine the midpoint, the system dynamically adjusts zone boundaries without requiring complex calculations, maintaining processing efficiency while adapting to changing sequence spaces.
Solution Approach 2:
The patent changes the parameter used for midpoint calculation from the complete sequence number to only the most significant bit. This parameter change simplifies the dynamic calculation while maintaining the ability to adapt zone boundaries to each packet's position in the sequence space.
Data Source
AI summary
A method and apparatus for determining whether a TCP packet lands in-zone or out-of-zone of a TCP sequence space. An anchor representing the TCP sequence number of the last TCP data byte, plus one, is updated each time a TCP data packet is received. When a new TCP packet is received, the most significant bit, bit [31], is extracted from the anchor. A two-bit value is formed by adding 1 to the extracted bit. This two-bit value is pre-pended to bits [30:0] of the anchor, as bits [32:31], to produce a 33-bit test value. Then, the sequence number of the last TCP byte of the received packet is then compared to the anchor and the test value. If the sequence number is greater than or equal to the anchor, and less than the test value, the packet lands in-zone and may be processed normally.