ARP Proxy Next-Hop Routing Engine for Switch Memory Optimization
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Solution Overview
Problem
High-speed network switches face memory capacity limitations when handling a large number of entries in their ARP tables due to frequent ARP requests from multiple host devices sending data packets to various IP addresses, leading to inefficient memory usage.
Innovation Solution
Implementing an ARP proxy next-hop routing engine that sends a single ARP request per route and updates the ARP table with a corresponding entry, using a forwarding information structure to forward subsequent packets to a next-hop address, thereby reducing the number of entries in the ARP table and optimizing memory usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the switch creates an ARP table entry for each distinct IP address to enable high-speed forwarding, then forwarding speed is improved, but memory capacity is exceeded
Solution Approach 1:
The patent merges multiple ARP table entries that share the same next-hop address into a single aggregated entry. Instead of maintaining separate entries for each destination IP address (10.1.1.1, 10.1.1.2, 10.1.1.3, etc.), the switch creates one aggregated entry that covers all destinations requiring the same next-hop, thereby reducing memory usage while preserving fast forwarding capability.
Solution Approach 2:
The aggregated ARP table entry serves multiple functions simultaneously: it enables fast forwarding for multiple destination IP addresses, stores a single next-hop MAC address, and reduces memory footprint. This universal entry structure allows the switch to handle various destinations without proportionally increasing memory consumption.
2Measurement precision
If the switch sends an ARP request for each data packet to a destination IP address, then accurate MAC address resolution is achieved, but the number of ARP requests increases
Solution Approach 1:
The switch performs preliminary ARP resolution by sending a single ARP request to obtain the next-hop MAC address in advance. This pre-resolved MAC address is then stored in the aggregated ARP table entry and reused for all subsequent packets destined to IP addresses within that route, eliminating the need for repeated ARP requests while maintaining accurate address resolution.
Solution Approach 2:
Instead of performing ARP resolution for each packet, the switch copies the resolved next-hop MAC address from the aggregated ARP table entry and applies it to multiple destination IP addresses. This copying mechanism allows the same MAC address to be reused for various destinations that share the same next-hop, reducing ARP request frequency while maintaining resolution accuracy.
Data Source
AI summary
In some examples, a switch includes a first communication interface to communicate with a first device, a second communication interface to communicate with a proxy device enabled to perform proxy address resolution, and a processor to receive a first data packet from the first device targeted to a first layer 3 network address, send, to the proxy device, an address resolution request to obtain a layer 2 network address corresponding to the first layer 3 network address, and responsive to receiving a response to the address resolution request, update a forwarding information structure to refer to a layer 3 network address of the proxy device, the forwarding information structure useable to forward a second data packet to the proxy device for transmission of the second data packet to a destination device.