NIC-Based Loop Prevention for Multipath Virtual L2 Networks
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Solution Overview
Problem
Virtual Layer 2 (L2) networks are susceptible to loops, which can cause broadcast storms and hinder the implementation of multiple paths due to the inherent lack of loop prevention mechanisms in L2 control protocols, and traditional Spanning Tree Protocol (STP) complicates multipath support.
Innovation Solution
Implementing rules in network interface cards (NICs) and using a lightweight, single-port STP to prevent loops while allowing multiple paths in virtual L2 networks, without the need for complex root bridge selection logic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Spanning Tree Protocol (STP) is used to prevent loops, then loop prevention is achieved, but device complexity and difficulty of implementing multipath support increase
Solution Approach 1:
The patent extracts the loop prevention function from the complex traditional STP protocol and implements it directly in the NIC hardware. This removes the need for complex root bridge selection logic and STP state machine implementation, achieving loop prevention while significantly reducing device complexity. The NIC simply blocks ports that would create loops based on simple path detection, without implementing full STP functionality.
Solution Approach 2:
The patent introduces a lightweight loop detection mechanism as an intermediary between the physical network layer and the virtual network layer. This intermediary monitors for loop conditions and triggers port blocking at the NIC level, providing loop prevention without requiring the full complexity of traditional STP protocol implementation in the virtual switch or host system.
2Adaptability or versatility
If multiple paths are implemented in virtual L2 networks, then network redundancy and performance are improved, but loop susceptibility increases
Solution Approach 1:
The patent segments the loop prevention function from the multipath routing function. The NIC handles loop prevention independently through port blocking based on simple path detection, while the virtual network layer maintains full multipath capability. This segmentation allows multiple paths to coexist with loop prevention without the complexity of traditional STP interfering with path selection.
Solution Approach 2:
The NIC performs self-service loop prevention by autonomously blocking ports that would create loops, without requiring coordination with other devices or complex protocol exchanges. This self-service approach enables the network to maintain multiple paths while each NIC independently ensures its own loop-free operation, achieving both multipath support and loop prevention.
Data Source
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AI summary
Techniques for loop prevention while allowing multipath in a virtual L2 network are described. In an example, a NIC supports the virtual L2 network. The NIC is configured to receive, via a first port of the NIC, an L2 frame that includes a source MAC address and a destination MAC address. Based on a loop prevention rule, the NIC transmits the L2 frame via its ports except the first port. In an additional example, the NIC is further configured to send an L2 frame to a host via the first port of the NIC. The L2 frame can be a BPDU. Upon receiving a BPDU from the host via the first port, the NIC determines that the BPDU is looped back and disables the first port.