Path MTU Discovery via ICMP Feedback and Probe Adjustment
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Solution Overview
Problem
Current information handling systems face challenges in determining the optimal path maximum transmission unit (MTU) size for communication paths in networks, which affects data packet transmission efficiency and reliability.
Innovation Solution
The system employs a method where a first node sends a test MTU packet with an initial MTU size, and subsequent nodes along the communication path compare and update the MTU size if necessary, with the final MTU size being acknowledged and set as the path maximum transmission unit discovery value, ensuring that data packets are transmitted within the network's capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed MTU size is used for data packet transmission, then the transmission process is simple, but packet drops occur when the fixed MTU size exceeds the path MTU of certain network sections
Solution Approach 1:
The system performs preliminary MTU discovery by sending probe packets through the communication path before actual data transmission. The probe packets carry test MTU sizes that are progressively adjusted based on ICMP feedback messages, allowing the system to pre-determine the optimal path MTU and avoid packet drops during subsequent data transmission.
Solution Approach 2:
The system implements a feedback mechanism where ICMP messages are used to convey MTU information from intermediate network devices back to the source. When a probe packet exceeds the path MTU, ICMP feedback messages provide information about the actual path MTU, allowing the source to adjust its transmission parameters and prevent future packet drops.
2Productivity
If the MTU size is reduced to accommodate the smallest path MTU, then packet drops are prevented, but transmission efficiency decreases due to increased packet fragmentation and overhead
Solution Approach 1:
The system performs preliminary MTU discovery by sending probe packets through the communication path before actual data transmission. The probe packets carry test MTU sizes that are progressively adjusted based on ICMP feedback messages, allowing the system to pre-determine the optimal path MTU and avoid packet drops during subsequent data transmission.
Solution Approach 2:
The system dynamically changes the MTU parameter based on the discovered path characteristics. Instead of using a fixed or conservatively small MTU size, the system adjusts the MTU parameter to match the actual path MTU, optimizing transmission efficiency while maintaining reliability by preventing packet drops.
3Measurement precision
If probe packets are sent to discover the path MTU, then accurate MTU determination is achieved, but network overhead and processing time increase
Solution Approach 1:
The system uses probe packets with progressively adjusted MTU sizes to discover the path MTU. Instead of testing all possible MTU values, the system uses a binary search or progressive adjustment approach, sending probe packets with increasingly larger MTU sizes until the path MTU is determined, reducing the number of probe packets needed compared to exhaustive testing.
Data Source
AI summary
An information handling system includes a memory to store a set of instructions, and a processor. The processor receives a maximum transmission unit (MTU) packet from a second information handling system via a first portion of a communication path, and in response to the information handling system not being a final destination information handling system compares a current MTU size of the communication path with a next MTU size of the communication path. In response to the next MTU size being smaller than the initial MTU size, the processor replaces the current MTU size with the next MTU size as the current MTU size, otherwise maintains the current MTU size as the current MTU size. The processor also provides the MTU packet to a next information handling system via the next portion of the communication path.