SD-WAN Flow Table Routing for Packet Consistency
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Solution Overview
Problem
In software-defined wide area networks (SD-WAN), ensuring that packets sent and received for the same application pass through the same network device is challenging, especially when multiple network devices are deployed at a site, as existing methods rely on deep packet inspection which requires both endpoints to pass through the same device, leading to interworking issues.
Innovation Solution
A packet sending method where network devices at a site establish tunnels with a second site and search a flow table for a target flow entry based on the data flow's identifiers, ensuring that packets are routed through the correct interface to maintain consistency, with mechanisms for handling cases where the target flow entry is not found, such as sending packets to other network devices or using local routes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple network devices are deployed in a site to ensure communication reliability, then system reliability is improved, but it becomes difficult to ensure that packets sent and received for the same application pass through the same network device
Solution Approach 1:
The system performs preliminary actions by establishing tunnels between network devices before packet transmission occurs. The flow table is pre-configured with flow entries that map flow identifiers to outbound interface identifiers, enabling consistent packet routing decisions to be made in advance without requiring real-time inspection or complex decision-making during packet processing.
Solution Approach 2:
The flow table acts as an intermediary mechanism between packet reception and packet forwarding decisions. Instead of directly inspecting packets and making routing decisions, the system uses the flow table as an intermediate structure that stores pre-computed routing information, thereby simplifying the packet processing operation and ensuring consistent behavior across multiple network devices.
2Adaptability or versatility
If deep packet inspection is used to identify application types, then packet processing capability is improved, but it requires both endpoints to pass through the same network device, creating interworking issues
Solution Approach 1:
The system extracts the essential routing decision-making capability from the complex deep packet inspection process. Instead of requiring both endpoints to pass through the same device for application identification, the patent extracts the flow identifier mapping information and stores it in the flow table, separating the routing decision function from the packet processing function and enabling simplified inter-device communication.
Solution Approach 2:
The flow table creates a copy of the routing decision logic that can be shared across multiple network devices. Rather than requiring each device to perform complex packet inspection and routing decisions independently, the flow table provides a replicated routing database that all devices can consult, reducing the complexity of interworking between multiple network devices.
Data Source
AI summary
A first network device of a plurality of network devices is provided. The first network device is configured to receive a first data packet from a second site; search a flow table stored in the first network device for a target flow entry whose flow identifier is of a first data flow, each entry comprises a flow identifier and a corresponding outbound interface identifier, the target flow entry is created when the first site sends a second data flow to the second site, a source address of the second data flow is a destination address of the first data flow, and a destination address of the second data flow is a source address of the first data flow; and if the target flow entry is found, send the first data packet through an interface corresponding to an outbound interface identifier in the target flow entry.