Fuzzy ARP Table for Reliable Packet Forwarding
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Solution Overview
Problem
In layer 3 communication, the delay in learning ARP entries leads to packet loss and service interruption, especially for delay-sensitive packets like voice, due to ARP entry conflicts or a full ARP table, causing unreliable forwarding.
Innovation Solution
A packet forwarding method that uses a fuzzy ARP table to map interfaces, port numbers, and MAC addresses, allowing the routing device to obtain the MAC address and port number of the next-hop device even if the precise ARP table search fails, thereby enabling timely and reliable forwarding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the routing device uses precise ARP table lookup for packet forwarding, then forwarding accuracy is improved, but forwarding delay increases and reliability decreases when ARP table is full or conflicts occur
Solution Approach 1:
The patent pre-establishes mapping relationships between interface IP addresses and MAC addresses in the routing table before actual packet forwarding is needed. This preliminary action eliminates the need for real-time ARP table lookups, thereby reducing forwarding delay while maintaining reliability even when ARP tables are full or conflicts occur.
Solution Approach 2:
The patent introduces an intermediary mechanism where the routing table stores pre-resolved interface-MAC address mappings that act as a mediator between the IP packet and the actual forwarding operation. This intermediary eliminates direct dependency on the ARP table, solving the contradiction between forwarding speed and reliability.
2Productivity
If the routing device performs ARP table lookup for every packet, then accurate next-hop delivery is achieved, but forwarding speed decreases due to repeated lookups
Solution Approach 1:
The routing table pre-stores the mapping relationships between interface IP addresses and corresponding MAC addresses before packet forwarding. This preliminary resolution of next-hop addresses eliminates repeated ARP table lookups for every packet, thereby improving forwarding speed while maintaining address resolution accuracy through the pre-computed mappings.
Solution Approach 2:
The patent performs address resolution in advance and stores the results in the routing table, doing more work upfront (excessive action) to avoid repeated lookups. This partial pre-computation of all possible next-hop mappings improves overall forwarding speed while ensuring accuracy through comprehensive pre-resolution.
3Reliability
If the ARP table is used for address resolution, then next-hop MAC address can be obtained, but service interruption occurs when ARP table is full or entry conflicts happen
Solution Approach 1:
The patent extracts the essential address resolution function from the ARP table and relocates it to the routing table. By taking out the MAC address mapping functionality from the ARP table, the system eliminates service interruptions caused by ARP table fullness or conflicts, while simplifying the overall address resolution process.
Solution Approach 2:
The routing table acts as an intermediary that pre-stores interface-MAC address mappings, mediating between the packet forwarding process and the ARP table. This intermediary mechanism ensures service continuity by providing fallback mappings when the ARP table is full or conflicts occur, reducing dependency on ARP table management complexity.
Data Source
AI summary
A packet forwarding method, includes: receiving an IP packet, and obtaining a destination IP address carried in the IP packet; obtaining an IP address of a next-hop device on a link from a routing table according to the destination IP address; obtaining a MAC address of the next-hop device and a corresponding port number according to the IP address of the next-hop device; and if failing to obtain the MAC address of the next-hop device and the corresponding port number, obtaining a corresponding interface on the routing device from the routing table according to the destination IP address, and obtaining the MAC address of the next-hop device and the corresponding port number from a fuzzy ARP table according to the interface; and forwarding the IP packet to the next-hop device according to the MAC address of the next-hop device and the port number.