SD-WAN Router Flow Rerouting to Prevent Packet Fragmentation
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Solution Overview
Problem
Existing SD-WAN technologies fail to address the issue of data packet fragmentation in SD-WAN routers, which is a costly and time-consuming operation, and induces processing load on stateful features like DPI, SNORT, and FW, leading to performance issues and jitter.
Innovation Solution
Implementing Data Fragmentation Logic in SD-WAN routers to monitor and reduce data fragmentation by determining PMTU for each egress link, detecting fragmentation rates, and rerouting data flows to links with higher PMTU to prevent excessive fragmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data packets exceed the PMTU of the egress link, then the data packet must be fragmented into multiple smaller packets, but this fragmentation operation increases processing load and induces jitter
Solution Approach 1:
The patent applies preliminary action by determining the PMTU of egress links before data flows are routed, and by monitoring fragmentation rates to proactively identify links causing excessive fragmentation. This allows the system to reroute data flows before excessive fragmentation occurs, preventing the need for time-consuming fragmentation and reassembly operations.
Solution Approach 2:
The patent implements feedback by continuously monitoring data packet fragmentation rates for each egress link and using this information to dynamically adjust routing decisions. The system feeds back fragmentation rate statistics to the routing logic, which then reroutes data flows away from links with high fragmentation rates, creating a closed-loop control system that optimizes packet delivery efficiency.
2Adaptability or versatility
If data flows are routed through egress links with lower PMTU, then routing flexibility is reduced, but data packet fragmentation rate increases
Solution Approach 1:
The patent applies dynamics by making routing decisions adaptive rather than static. The system dynamically adjusts data flow routing based on real-time monitoring of fragmentation rates and PMTU characteristics of different egress links. This allows the routing configuration to evolve and adapt to changing network conditions, optimizing both flexibility and efficiency.
Solution Approach 2:
The patent changes the routing parameter selection by incorporating fragmentation rate statistics into the routing decision process. Instead of relying solely on static routing metrics, the system uses fragmentation rate as an additional parameter to evaluate egress link suitability, thereby selecting routes that minimize fragmentation while maintaining routing flexibility.
3Measurement precision
If fragmentation monitoring is performed on a per-flow basis, then routing precision is improved, but computational complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the monitoring task into per-flow fragmentation rate tracking. Each data flow is monitored independently for fragmentation events, allowing precise identification of which specific flows are affected by which egress links. This segmented approach enables targeted rerouting decisions for individual flows rather than blanket routing changes.
Solution Approach 2:
The patent introduces an intermediary layer of fragmentation statistics collection and analysis that sits between the data plane and routing decisions. This intermediary component aggregates fragmentation rate information and presents processed statistics to the routing logic, simplifying the complexity by providing pre-processed information rather than requiring the routing logic to perform raw packet analysis.
Data Source
AI summary
Techniques are described for avoiding data packet fragmentation in a routing device such as a router or network switch. Path Maximum Transport Unit (PMTU) values are monitored for a plurality of egress links of a networking device. A statistical analysis of fragmentation rates is performed. The statistical analysis can be performed on a per-link basis, per-flow basis or both per-link and per-flow basis. If the packet fragmentation rate of data flows through a particular egress link exceeds a determined threshold value, one or more data flows can be re-routed to a different egress link having a higher PMTU, thereby preventing data packet fragmentation.