Lightweight Host Multihoming via Shared Virtual MAC
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Solution Overview
Problem
Existing host multihoming solutions, such as Virtual Link Trunking (VLT) and separate IP interfaces for each host, are either heavyweight in software implementation or impose heavy address consumption and complexity, lacking robustness in case of link failures.
Innovation Solution
A lightweight host multihoming approach using two ToR switches connected to multiple hosts without synchronization protocols, employing a shared virtual MAC address and virtual IP address for traffic load sharing and link aggregation, with /30 or /31 subnets for efficient address management and BFD for link liveness detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VLT (Virtual Link Trunking) is implemented for inter chassis link between two ToR switches, then connection reliability is improved, but software implementation complexity increases
Solution Approach 1:
The patent extracts the complex VLT synchronization protocol functionality from the switch software and replaces it with a simplified approach using standard link aggregation protocols (LACP/PAgP) and independent IP routing. Each ToR switch operates independently without requiring complex inter-switch synchronization, thereby reducing software implementation complexity while maintaining connection reliability through redundant paths and protocol-based failover.
2Ease of operation
If separate IP interfaces are assigned to each host leg, then address consumption increases, but host control over multihoming improves
Solution Approach 1:
The patent merges multiple host legs into a single logical interface using link aggregation protocols (LACP/PAgP). This allows the host to maintain control over multihoming configuration while presenting a unified interface to the network, thereby reducing IP address consumption from multiple addresses per leg to a single address per aggregated interface, while still providing redundancy and load balancing capabilities.
3Reliability
If tunneling is used to maintain TCP connections during interface failures, then connection robustness improves, but data path overhead and complexity increase
Solution Approach 1:
The patent enables the network infrastructure (ToR switches and core routers) to automatically detect link failures and reroute traffic using standard routing protocols and link aggregation failover mechanisms. This eliminates the need for host-based tunneling solutions, as the network itself provides the robustness and failover capability, thereby reducing data path overhead and complexity while maintaining connection reliability through automatic path switching.
Data Source
AI summary
Described herein are systems and methods for host multihoming with no state synchronization between top-of-rack (ToR) switches coupled to multiple hosts. ToR switches of a multi-homing system share a virtual MAC address and respond to Address Resolution Protocol (ARP) requests and/or Neighbor Discovery (ND) solicitations for a default gateway IP address from the host with the virtual MAC address. Ports on a ToR switch may be configured either with a static ARP and/or ND entry, or be configured to learn via a discovery protocol. The lightweight host multihoming system may have modified flooding behavior, ARP/ND handling, and data path forwarding. ARP/ND traffic from a host is processed by a ToR switch, while other multicast traffic may be discarded. Embodiments of the host multihoming system provide a lightweight solution for software implementation with minimal changes imposed on the host or network design.