IPv4 Fragment Forwarding Without Reassembly
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Solution Overview
Problem
Network devices face inefficiencies in forwarding IPv4 packets to IPv6 networks due to the need for reassembly and anti-spoofing checks, which consume processor and memory resources and can result in re-fragmentation and processing delays.
Innovation Solution
Implementing techniques that allow network devices to buffer and encapsulate IPv4 packet fragments within IPv6 packets without reassembling the entire IPv4 packet, performing address and port mapping only when destination and source information is complete, and conducting anti-spoofing checks based on partial fragments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If network devices reassemble IPv4 packets from fragments before encapsulation, then forwarding accuracy is improved, but processor and memory resource consumption increases
Solution Approach 1:
The patent applies segmentation by maintaining fragments in their separate states rather than reassembling them into complete packets. Each fragment is independently encapsulated in an IPv6 packet with fragment-specific metadata, allowing the network device to forward fragments without performing resource-intensive reassembly operations while still ensuring correct delivery through destination port mapping performed on available fragment information
Solution Approach 2:
The patent performs partial action by conducting destination port mapping on fragments even when complete packet information is not available. Instead of waiting for all fragments to arrive before performing any mapping operations, the system performs mapping on partial information from individual fragments, reducing processing delays and resource consumption while maintaining forwarding accuracy
2Measurement precision
If network devices buffer fragments until destination port information is complete, then MAP-E mapping accuracy is improved, but forwarding delay increases
Solution Approach 1:
The patent performs MAP-E destination port mapping on fragments using partial information available from individual fragments rather than waiting for complete packet assembly. The system extracts destination port information from available fragments and performs mapping immediately, accepting that some mapping operations may be performed on incomplete information rather than delaying processing until all fragments arrive
Solution Approach 2:
The patent uses temporary fragment buffers with short retention periods, holding fragments only briefly until destination port information becomes available or a timeout occurs. These buffers are designed for minimal resource consumption and are cleared after brief retention, allowing the system to balance between waiting for complete information and avoiding excessive buffering delays
3Reliability
If network devices perform anti-spoofing checks on reassembled packets, then security is improved, but processing complexity increases
Solution Approach 1:
The patent applies segmentation to security checking by performing anti-spoofing validation on individual fragments rather than requiring complete packet reassembly. The system checks source addresses, destination addresses, and other security-relevant fields in each fragment independently, reducing the complexity of state management required for reassembly while maintaining security through fragment-level validation
Solution Approach 2:
The patent performs preliminary anti-spoofing checks on fragments before encapsulation and forwarding. By validating security attributes of fragments early in the processing pipeline, the system prevents malicious packets from entering the network without requiring complex reassembly operations, thereby improving security while keeping processing complexity manageable
4Productivity
If network devices encapsulate fragments individually without reassembly, then forwarding speed is improved, but destination devices must perform reassembly
Solution Approach 1:
The patent maintains the segmented nature of packet fragments throughout the encapsulation and forwarding process. Each fragment is independently encapsulated in an IPv6 packet with preserved fragment identification information, allowing destination devices to perform reassembly using standard protocols. This approach enables network devices to forward fragments at high speed without reassembly while ensuring destination devices can reconstruct original packets using the embedded fragment metadata
Data Source
AI summary
A network device may forward fragments of an IPv4 network packet encapsulated in IPv6 network packets from an IPv6 network to an IPv4 network without reassembling the IPv4 network packet. The network device may receive and buffer the one or more fragments of a fragment flow associated with the IPv4 network packet until it receives a fragment of the fragment flow that includes an indication of the source port of the IPv4 network packet. When the network device receives the fragment that includes the indication of the source port of the IPv4 network packet, the network device may dispatch each fragment of the fragment flow that it has received to the IPv4 network.