Multiple Active L3 Gateways for Logical Network Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing virtualized networks lack effective methods for implementing logical routers that can seamlessly connect virtual machines across different subnets, leading to inefficiencies in data traffic management and reliability in case of router failures.
Innovation Solution
A network control system that utilizes high-availability gateways to establish logical router connections between virtual machines, with centralized or distributed implementations, where flow entries manage packet routing through tunnels to active and standby gateways, ensuring continuous operation even if primary gateways fail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single active gateway is used for L3 routing in virtualized networks, then the routing control is simplified and centralized, but the network reliability deteriorates when the active gateway fails
Solution Approach 1:
The patent pre-configures multiple standby gateways before any failure occurs. The network controller designates one gateway as active and others as standby, with all gateways pre-provisioned with routing table entries. This preliminary setup ensures that when the active gateway fails, a standby gateway can immediately take over without requiring complex real-time reconfiguration, thus maintaining network reliability while keeping control mechanisms relatively simple.
Solution Approach 2:
The patent implements redundancy by provisioning multiple gateway instances with identical routing capabilities before failure occurs. The standby gateways act as a cushion or backup that absorbs the impact of active gateway failure. This beforehand cushioning ensures continuous network operation by having pre-positioned backup resources that can immediately assume the active role, resolving the contradiction between simplified control and reliable operation.
2Reliability
If multiple standby gateways are provisioned for failover, then the network reliability improves, but the system complexity increases
Solution Approach 1:
The patent introduces a network controller as an intermediary that manages the complexity of multiple gateway provisioning. The controller handles the designation of active and standby gateways, distributes routing table entries to appropriate gateways, and manages failover logic. This intermediary absorbs the management complexity, allowing multiple standby gateways to be provisioned for improved reliability while the controller systematically handles the coordination, preventing exponential growth in system complexity.
Solution Approach 2:
The patent segments the gateway management function into distinct roles (active gateway, standby gateways) and separates control plane functions from data plane functions. The network controller handles control plane decisions about gateway designation and routing table distribution, while individual gateways handle data plane packet forwarding. This segmentation allows multiple standby gateways to be managed systematically without overwhelming system complexity, as each component has a specific, simplified responsibility.
3Device complexity
If centralized gateway implementation is used, then the routing logic is simplified, but the packet forwarding efficiency deteriorates due to additional tunneling overhead
Solution Approach 1:
The patent applies local quality by allowing different gateway implementations to coexist based on specific network requirements. Some gateways can be configured with centralized routing logic for simplicity, while others can be positioned closer to virtual machine hosts to reduce tunneling distance. The system allows selective placement of gateway functions, enabling optimized packet forwarding paths for time-sensitive traffic while maintaining simplified routing logic where appropriate, thus resolving the contradiction between routing simplicity and forwarding efficiency.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for a network controller in a network control system that manages a plurality of logical networks (100). The method receives a specification of a logical network (100) that comprises a logical router (115) with a logical port that connects to an external network (120). The method selects several host machines to host a L3 gateway that implements the connection to the external network (120) for the logical router (115) from a set of host machines designated for hosting logical routers. The method generates data tuples for provisioning a set of managed forwarding elements that implement the logical network to send data packets that require processing by the L3 gateway to the selected host machines. The data tuples specify for the managed forwarding elements to distribute the data packets across the selected host machines.