Fault Tolerant Network Architecture Using Virtual IP Addresses
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Solution Overview
Problem
Current methods for achieving high availability in IP networks are limited by the requirement that High Availability (HA) nodes must be located on the same Local Area Network (LAN), which restricts location and distance, and can lead to premature failover and latency due to local network failures, especially when HA nodes are connected to multiple LANs.
Innovation Solution
A fault-tolerant network architecture that employs virtual IP addresses not tied to any physical interface or subnet, allowing these addresses to be floated between nodes across different physical locations, with monitoring and routing protocols ensuring seamless failover and load balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HA nodes are located on the same LAN to share floating IP addresses, then network availability is improved through failover capability, but location and distance constraints are imposed on HA nodes
Solution Approach 1:
The patent introduces a gateway device as an intermediary that maintains the floating IP address and performs address translation. HA nodes communicate using their own local IP addresses without directly sharing floating IPs. The gateway mediates external communications, translating between floating IP and local IP addresses, thereby enabling HA nodes to be geographically distributed while maintaining failover capability.
2Reliability
If all redundant interfaces are on the same LAN to share IP addresses for load balancing, then redundancy is achieved, but premature failover occurs due to recoverable local network failures
Solution Approach 1:
The patent segments the network into multiple independent LANs, with each HA node having interfaces on different LANs. The gateway device segments the floating IP management from the HA nodes themselves. This segmentation allows failure isolation - a failure on one LAN does not trigger premature failover of the entire HA cluster, as the gateway can detect and handle failures independently while maintaining service continuity through other LANs.
3Reliability
If HA nodes are connected to multiple LANs to improve redundancy, then load balancing capability is enhanced, but a single LAN failure causes unavailability of the HA node
Solution Approach 1:
The gateway acts as an intermediary that decouples the HA nodes from direct external communications. HA nodes communicate only with the gateway using their stable local IP addresses. The gateway handles all external communications and failover logic. This way, even if one LAN fails, the HA node can continue communicating through other LANs via the gateway, preventing complete unavailability.
Solution Approach 2:
The system implements prior cushioning by having HA nodes maintain multiple network interfaces on different LANs with their own IP addresses, and by having the gateway maintain the floating IP address independently. This preparatory configuration ensures that if one LAN fails, there are already alternative communication paths in place, cushioning against the failure impact without causing service interruption.
Data Source
AI summary
A fault tolerant network architecture employs a network node including a first network interface to an addressable network. The first network interface is assigned a first network interface IP address defined by a first IP address range. The network node also includes at least one virtual IP address defined by an IP address range outside of the first IP address range. At least one virtual address is advertised to the addressable network from the first network interface, and packets addressed to the at least one virtual IP address can be routed to the first network interface.