VXLAN Routing Loop Prevention via Local Remote Grouping
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Solution Overview
Problem
In VXLAN networks, routing loops occur when multiple VMs with shared IP addresses are connected to different VTEP devices, leading to incorrect packet forwarding and load balancing issues.
Innovation Solution
A network device groups routes in the VRF table into local and remote routing groups based on address types, using tunnel identifiers to determine packet origin and prevent forwarding to another VTEP device, thus avoiding routing loops and ensuring normal packet forwarding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If VXLAN tunnel endpoint devices forward packets from network side to VMs using standard routing tables, then packet forwarding flexibility is improved, but routing loops occur causing packet forwarding failure
Solution Approach 1:
The patent segments the routing table into two distinct parts: a conventional routing table for standard packet forwarding, and a VXLAN-specific routing table for handling VXLAN tunnel packets. This segmentation prevents routing loops by ensuring VXLAN packets are handled through a dedicated forwarding path that doesn't loop back to other VTEP devices, while maintaining flexibility in both routing domains simultaneously.
Solution Approach 2:
The patent introduces a VXLAN-specific routing table as an intermediary structure between the conventional routing table and the packet forwarding process. This intermediary table acts as a buffer that intercepts VXLAN packets before they can enter the conventional routing loop, processes them through appropriate VXLAN forwarding rules, and delivers them to the correct VMs without causing routing loops.
2Productivity
If multiple VMs share the same IP address across different VTEP devices, then resource utilization is improved, but routing loops occur causing VM overload
Solution Approach 1:
The patent applies local quality by making the routing behavior specific to the packet type and destination. The VXLAN-specific routing table contains locally optimized forwarding rules that consider the local network topology and VM distribution. This allows each VTEP device to handle VXLAN packets with locally-appropriate forwarding decisions, preventing routing loops while maintaining load distribution across VMs with shared IP addresses.
3Device complexity
If a single routing table is used for all packet types, then device complexity is reduced, but routing loops occur requiring additional routing logic
Solution Approach 1:
The patent segments the routing functionality into two separate routing tables: a conventional routing table for standard IP routing and a VXLAN-specific routing table for VXLAN tunnel packet forwarding. This segmentation increases structural complexity slightly but eliminates the need for complex routing loop prevention logic within a single table, as each table handles specific packet types with dedicated forwarding rules.
Data Source
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AI summary
A packet forwarding method and a network device are provided. The method is applied to the network device. The method specifically includes: A network device obtains a first tunnel identifier of a first packet. When the first tunnel identifier is a first value, the network device forwards the first packet based on a first routing group in a virtual routing and forwarding VRF table. The first routing group consists of one or more local routes, and each next-hop outbound interface of the one or more local routes is a local outbound interface. The VRF table further includes a second routing group, and the second routing group includes one or more remote routes whose next-hop outbound interfaces are remote outbound interfaces. The network device forwards the packet based on a local routing group including only a local route in the VRF table, so that the packet can be forwarded to a local virtual machine for processing, and is not forwarded to another tunnel endpoint device, to avoid a routing loop during packet forwarding.