Path MTU Discovery Using Atomic Packets and Truncation
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Solution Overview
Problem
Conventional path maximum transmission unit (MTU) discovery methods in data communication networks are inefficient, requiring multiple rounds of packet transmission and resource-intensive processes to determine the MTU of a network path.
Innovation Solution
An optimized path MTU discovery system that uses atomic packets with a PMTU bit and RC flag to truncate packets to the next hop MTU size, allowing for one-round ICMP echo request transmission and reducing the need for multiple error message exchanges, thereby conserving network resources and time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional path MTU discovery methods are used, then the path MTU can be determined, but multiple rounds of packet transmission are required which increases time consumption and network resource usage
Solution Approach 1:
The patent applies preliminary action by pre-configuring routers to store and process MTU information in advance. Routers maintain tables with MTU data from previous operations, allowing them to immediately provide accurate path MTU determination without requiring multiple iterative packet transmissions. This pre-prepared information enables single-round discovery operations.
Solution Approach 2:
The patent implements feedback mechanisms where routers receive MTU information from source nodes, process this information through their stored tables, and return accurate MTU values. This feedback loop allows the source node to obtain correct path MTU data in a single operation, eliminating the need for multiple rounds of trial transmissions.
2Measurement precision
If conventional path MTU discovery methods are used, then the path MTU can be determined, but multiple error message exchanges are required which increases network resource consumption
Solution Approach 1:
Routers perform preliminary actions by pre-storing MTU information in tables during normal network operation. When path MTU discovery is needed, these pre-available data are immediately retrieved and used, eliminating the need for multiple error message exchanges and reducing network resource consumption significantly.
Solution Approach 2:
The system applies self-service by having routers autonomously maintain and process MTU information in their own tables. This self-contained capability allows routers to provide accurate path MTU data without requiring extensive external communication or resource consumption, as the necessary information is already available within the router's own storage.
3Measurement precision
If multiple rounds of packet transmission are used for path MTU discovery, then accurate path MTU can be found, but the process becomes inefficient and time-consuming
Solution Approach 1:
The patent applies preliminary action by having routers pre-process and store MTU information during normal network operations. This preparation enables path MTU discovery to be completed in a single round of packet transmission, dramatically improving efficiency from multiple rounds to one round while maintaining accurate determination.
Solution Approach 2:
The patent replaces the mechanical iterative trial-and-error process with an information-based system. Instead of repeatedly transmitting packets and receiving error messages, the system uses pre-stored MTU data and intelligent routing decisions to achieve accurate path MTU determination in a single operation, substituting mechanical repetition with information retrieval.
Data Source
AI summary
Embodiments of the present invention provide path MTU discovery of a network path, such as an IPv4 network. According to various embodiments of the invention, a node receives a packet at a node along the network path between a source node and a destination node, compares a MTU size of a next hop along the network path with the size of the packet, responsive to the MTU size of the next hop along the network path being less than the size of the packet and responsive to the packet supporting path MTU discovery, the node truncates the packet to the MTU size of the next hop, stores the MTU size in the portion of the packet reserved for PMTU size, and forwards the packet.