Multilink PPP Bundle Fragment Drop Heuristic
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Solution Overview
Problem
In multilink point-to-point protocol (PPP) bundles, existing load-balancing and fragment reassembly algorithms face challenges in efficiently detecting and handling dropped fragments, leading to increased latency and packet corruption due to differential delays across links, with conventional methods failing to detect fragment loss effectively at fast packet rates and finite buffering conditions.
Innovation Solution
A new heuristic method is introduced that calculates a 'remainder time' value based on differential delay considerations of the bundle's links, using a remainder timer to determine when to drop fragments and reassemble packets, thereby improving fragment drop detection and reducing latency by selecting a drop timeout value tailored to the multilink PPP bundle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fragment reassembly algorithms are used in multilink PPP bundles, then packet reassembly can be performed, but fragment drop detection is ineffective leading to increased latency and packet corruption
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the expected arrival time windows for each fragment based on differential delay considerations before reassembly is needed. When a fragment arrives, the system immediately compares its arrival time against the pre-computed window to detect drops, rather than waiting for reassembly to fail. This proactive approach enables early detection of fragment loss, reducing both latency and corruption.
2Productivity
If load balancing distributes packets across multiple parallel links, then bandwidth utilization increases, but differential delays cause fragments to arrive out of order increasing reassembly complexity
Solution Approach 1:
The system performs preliminary calculation of expected fragment arrival time windows during the load balancing phase, taking into account the differential delays of each link. This pre-computation stores the time window within which each fragment should arrive, allowing the reassembly algorithm to simply compare actual arrival times against these pre-established windows, thereby reducing reassembly complexity while maintaining high bandwidth utilization.
3Productivity
If fast packet rates are maintained in multilink bundles, then throughput is high, but conventional methods fail to detect fragment loss effectively
Solution Approach 1:
The patent implements preliminary calculation of precise expected arrival time windows for each fragment based on the specific characteristics of the multilink bundle and differential delays. These pre-computed windows provide precise reference points against which actual fragment arrivals are compared, enabling accurate fragment loss detection even at high packet throughput rates where conventional methods would fail.
4Reliability
If timeout values are set for fragment reassembly, then incomplete packets can be dropped, but fixed timeout values do not account for differential delays across links
Solution Approach 1:
The patent applies dynamics by replacing fixed timeout values with dynamic, fragment-specific expected arrival time windows. Each fragment is assigned a customized time window based on its sequence number, size, and the differential delays of the links it traversed. This dynamic approach allows the system to adapt to varying delay conditions across different fragments and links, improving both reliability and adaptability simultaneously.
Data Source
AI summary
Systems and methods consistent with the present invention provide a better fragment drop heuristic that determines a per-fragment determined “remainder time” value to trigger potential drops on the whole bundle. A per-bundle drop timeout value is assumed. This value is to be configured based on differential delay considerations of the various links that constitute the bundle. The arrival time of a fragment to a reassembly algorithm triggers a remainder timer. When the reassembly algorithm instance actually processes the fragment, the “remainder time,” which is difference of a bundle drop timeout and time elapsed on the remainder timer, is used to determine whether the fragment and the other fragments of the packet should be dropped.