Host Route Injection for ARP Cache Management
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Solution Overview
Problem
Scaling compute host environments with thousands of Virtual Machines (VMs) faces challenges due to ARP cache limitations, requiring either expensive router upgrades or sub-network reduction, and existing solutions for IP mobility and routing inefficiencies do not adequately address ARP cache size issues.
Innovation Solution
Implementing a network device system that injects a host route and next hop into the router, caching only the ARP information of the next hop in the ARP table to route network traffic, facilitating IP-mobility while avoiding ARP cache size limitations, and allowing implementation on existing infrastructure without significant upgrades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the router maintains ARP entries for all VM IP addresses, then IP mobility is supported, but the ARP cache size limitation is exceeded requiring expensive router upgrades
Solution Approach 1:
The patent segments the ARP cache management by introducing a separate host route table that stores VM IP address mappings, while the ARP cache only maintains entries for physical host MAC addresses. This segmentation allows IP mobility to be tracked in the host route table without consuming ARP cache entries, resolving the contradiction between supporting IP mobility and maintaining ARP cache size limits.
Solution Approach 2:
The patent introduces a host route table as an intermediary data structure between the routing table and ARP cache. This intermediary stores the mapping between VM IP addresses and physical host MAC addresses, allowing the router to resolve VM IPs to host MACs without creating ARP entries for each VM IP, thus supporting IP mobility while avoiding ARP cache exhaustion.
2Manufacturing precision
If the router maintains ARP entries for all VM IP addresses, then routing accuracy is improved, but device cost increases due to expensive router upgrades
Solution Approach 1:
The patent segments routing information storage into multiple specialized data structures: a host route table for VM IP to host MAC mappings, a routing table for network destinations, and an ARP cache for physical host MAC addresses. This segmentation maintains routing accuracy for VMs while preventing the ARP cache from growing beyond its size limits, avoiding the need for expensive router upgrades.
Solution Approach 2:
The patent changes the parameter of what gets cached in the ARP table from VM IP addresses to physical host MAC addresses. This parameter change allows the ARP cache to maintain a manageable size while routing accuracy is preserved through the host route table which maintains the VM IP to host MAC mappings needed for accurate packet forwarding.
3Quantity of substance
If the sub-network size is reduced to fit ARP cache limitations, then ARP cache size is controlled, but network scalability is reduced
Solution Approach 1:
The patent segments the network address resolution function into two parts: the host route table handles VM IP address mappings without size limits, while the ARP cache maintains only physical host MAC addresses within its size limits. This segmentation enables network scalability to thousands of VMs while keeping the ARP cache size controlled, as the host route table absorbs the scalability requirements.
Solution Approach 2:
The patent creates a copy of the VM IP to MAC mapping functionality in the host route table, separate from the traditional ARP cache mechanism. This copying allows the system to maintain ARP cache size control while achieving network scalability through the parallel host route table structure that can accommodate unlimited VM IP mappings.
Data Source
AI summary
An example of network routing comprising a host route injection that can include injecting a host route and a next hop of the host route into a routing table. The host route can be injected into a top of rack network device and transferred to an Aggregation network device routing table. The routing entry can be updated by sharing routing updates from the compute host through the top of rack network device.