Determining Layer 2 Default Gateway via Switch Forwarding Tables
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining the Layer 2 default gateway in network topology, especially in enterprise and wide area networks, are inefficient as they require probing endpoints, which is not scalable and raises security concerns, and often rely on unreliable tools like trace route.
Innovation Solution
Systems and methods that determine the Layer 2 default gateway by traversing a Layer 2 forwarding domain using algorithms like depth-first search or breadth-first search, identifying candidate gateways, and determining actual gateways based on their connectivity and redundancy, without directly accessing endpoint configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If endpoint probing is used to determine Layer 2 default gateway, then gateway information can be obtained, but scalability is poor and security concerns arise
Solution Approach 1:
The patent introduces network switches as intermediary devices to obtain gateway information. Instead of directly probing endpoints, the system queries switches that are already present in the network path. The switches maintain forwarding table information that includes default gateway mappings, allowing the system to extract gateway information from these intermediaries. This resolves the contradiction by providing accurate gateway data through existing network infrastructure without requiring direct endpoint access, thereby maintaining scalability and security while achieving measurement precision.
Solution Approach 2:
The patent leverages the self-service capability of network switches by utilizing their existing forwarding table data structures. The switches already maintain information about default gateways in their forwarding tables as part of their normal operation. The system queries this pre-existing information rather than requiring the switches or endpoints to perform additional probing operations. This approach maintains high scalability because the switches can serve multiple path trace requests using their already-collected data, eliminating the need for repeated endpoint interactions.
2Ease of operation
If traditional trace route tools are used, then path tracing can be performed, but the information available is insufficient and time consumption is high
Solution Approach 1:
The patent applies preliminary action by having network switches pre-collect and maintain forwarding table information during their normal operation. The forwarding tables are continuously updated as traffic flows through the network, so when a path trace operation is needed, the information is already available. This eliminates the need for time-consuming probing operations during actual path tracing, as the system can directly query the pre-existing forwarding table data. The preliminary collection of gateway information in the forwarding tables during routine switch operation resolves the time loss issue while maintaining ease of operation.
Solution Approach 2:
The patent replaces the mechanical probing system with an information query system. Instead of using traditional trace route tools that send test packets and wait for responses (a mechanical interaction process), the system substitutes this with direct queries to switch forwarding tables. This substitution eliminates the time-consuming nature of traditional trace route operations while preserving path tracing capability. The forwarding table data structure serves as a pre-computed information repository that can be queried instantly, replacing the iterative mechanical probing process.
3Measurement precision
If endpoint configurations are accessed to obtain default gateway, then accurate gateway information is obtained, but the process does not scale in enterprise and WAN networks
Solution Approach 1:
The patent uses network switches as intermediaries to obtain default gateway information that would otherwise require direct endpoint configuration access. The switches maintain forwarding tables that contain gateway information collected from multiple endpoints, effectively aggregating this data in an intermediary location. This approach maintains measurement precision because the forwarding tables contain accurate gateway mappings, while reducing device complexity by eliminating the need for direct endpoint configuration access in each path trace operation. The switch acts as a centralized information repository that simplifies network management.
Solution Approach 2:
The patent makes the switch forwarding table serve multiple functions: it performs its primary role of packet forwarding while simultaneously serving as a database for path trace operations. The forwarding table data structure is universally applicable across different path trace scenarios, providing gateway information for any endpoint without requiring endpoint-specific configuration access. This multi-functionality resolves the contradiction by allowing a single network element (the switch) to provide accurate gateway information for multiple endpoints, thereby reducing overall network management complexity while maintaining measurement precision.
Data Source
AI summary
Disclosed are system, methods, and non-transitory computer readable media for accurately calculating a default gateway of an endpoint without probing the endpoint for the configured values to determine the path between network elements. Tracing the path of a flow in a network and displaying that on a user interface is extremely useful for network troubleshooting purposes. In order to find the gateway the flow would take out of the L2 domain, the endpoint's L2 default gateway is required. Usually the L2 gateway for network endpoints is configured on the endpoints themselves and this information cannot be accessed by network controllers (e.g., APIC-EM) directly. In such cases APIC-EM needs to determine the L2 gateway based on the information available to it from the network elements, instead of the endpoints themselves.