Logical Router Reflection Route for Link Local Packet Processing
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Solution Overview
Problem
Logical routers assigned a single virtual MAC address face challenges in determining the correct logical interface to use for response packets, as all logical interfaces share the same link local address, leading to potential packet drops.
Innovation Solution
The implementation of a reflection route table that dynamically inserts the identifier for the ingress interface as the egress interface for response packets, allowing the logical router to correctly route response packets back to the originating workload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a logical router uses a single virtual MAC address for all logical interfaces, then device complexity is reduced and resource utilization is improved, but the router cannot determine which logical interface to use for response packets, leading to packet drops
Solution Approach 1:
The patent segments the link local address space by creating unique link local addresses for each logical interface using the format fe80::6cbb:xxxx:xxxx:1/64, where xxxx represents unique identifiers for different logical interfaces. This segmentation allows the router to distinguish between multiple logical interfaces while maintaining a unified virtual MAC address approach.
Solution Approach 2:
The patent introduces an intermediary mapping mechanism that associates each logical interface with its unique link local address. This mapping table acts as an intermediary between the single virtual MAC address and the multiple logical interfaces, enabling the router to determine the correct egress interface for response packets.
2Ease of operation
If each logical interface has the same link local address, then ease of operation is improved and configuration is simplified, but the router loses the ability to route response packets correctly, resulting in service failure
Solution Approach 1:
The patent applies local quality by assigning unique link local addresses to each logical interface based on their specific identifiers. Each logical interface maintains its own distinct link local address (fe80::6cbb:xxxx:xxxx:1/64) while the overall configuration remains simplified through the consistent naming convention and single virtual MAC address approach.
Data Source
AI summary
A method receives a request packet from a workload at a first logical interface of a logical router and determines that a source address is a first link local address for the workload and a destination address is a second link local address for the first logical interface. A second logical interface includes the second link local address. The method stores an identifier for the first logical interface as an egress interface. The identifier distinguishes the first logical interface from the second logical interface. A service is performed for the request packet and a response packet is generated. The response packet includes the source address of the second link local address for the first logical interface and the destination address of the first link local address for the workload. The method uses the identifier to select the first logical interface as the egress interface to send the response packet.