Low Latency Ethernet for Data Center Storage Traffic

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Solution Overview

Problem

Data center networks face complexity and high costs due to redundant connectivity requirements for high availability, with existing solutions like Infiniband being costly and not scalable for large enterprises, and Fibre Channel being inflexible in handling congestion and latency.

Innovation Solution

Implementing a Low Latency Ethernet (LLE) solution that transforms Fibre Channel frames into Ethernet format, using multiple virtual lanes with different buffering and congestion management rules to create a high-bandwidth, low-latency network with dynamic bandwidth allocation and active buffer management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If redundant Ethernet connectivity is implemented for high availability, then reliability is improved, but device complexity and cost increase

Engineering Contradiction:

Improvehigh availabilityVSAvoidconnectivity complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges Fibre Channel and Ethernet networks into a unified infrastructure where FC traffic is encapsulated within Ethernet frames. This allows storage traffic to traverse the existing Ethernet network using standard Ethernet switches, eliminating the need for separate FC switches and redundant FC connectivity while maintaining high availability through Ethernet's own redundancy mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Ethernet is positioned as a universal network that can handle both traditional IP traffic and storage traffic (FC-Over-Ethernet). The Ethernet network becomes multi-functional, serving both data communication and storage I/O purposes, thereby reducing overall network complexity while maintaining reliability through Ethernet's robust error correction and redundancy features.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If Fibre Channel is used for storage traffic, then reliability is improved, but adaptability and flexibility decrease

Engineering Contradiction:

Improvestorage traffic reliabilityVSAvoidcongestion handling flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental parameters of the storage network by running FC traffic over Ethernet. This allows Ethernet's superior congestion management capabilities (flow control, packet switching, QoS) to be applied to storage traffic, providing both reliability through FC protocols and adaptability through Ethernet's flexible congestion handling mechanisms.

Inventive Principle:

Principle #35Parameter changes

3Speed

If Infiniband is deployed for high performance networking, then speed is improved, but device complexity and cost increase

Engineering Contradiction:

Improvenetwork speedVSAvoidnetwork complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent replaces expensive, complex Infiniband hardware with standard Ethernet infrastructure. By encapsulating FC traffic in Ethernet frames, the solution uses readily available, cost-effective Ethernet switches and cables to achieve high-speed storage traffic, eliminating the need for specialized Infiniband hardware while maintaining performance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Adaptability or versatility

If Ethernet is used for storage traffic, then adaptability is improved, but reliability deteriorates due to packet loss and collisions

Engineering Contradiction:

Improvenetwork versatilityVSAvoidstorage traffic reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces an intermediary layer - the Ethernet network - that mediates between storage devices and servers. Ethernet's robust error correction, flow control mechanisms, and packet switching capabilities serve as intermediaries that maintain reliability while providing the versatility and congestion management benefits of Ethernet infrastructure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7969971B2Ethernet extension for the data center

Publication Date: 2011.06.28 CISCO TECHNOLOGY INC

AI summary

The present invention provides methods and devices for implementing a Low Latency Ethernet (“LLE”) solution, also referred to herein as a Data Center Ethernet (“DCE”) solution, which simplifies the connectivity of data centers and provides a high bandwidth, low latency network for carrying Ethernet and storage traffic. Some aspects of the invention involve transforming FC frames into a format suitable for transport on an Ethernet. Some preferred implementations of the invention implement multiple virtual lanes (“VLs”) in a single physical connection of a data center or similar network. Some VLs are “drop” VLs, with Ethernet-like behavior, and others are “no-drop” lanes with FC-like behavior. Some preferred implementations of the invention provide guaranteed bandwidth based on credits and VL. Active buffer management allows for both high reliability and low latency while using small frame buffers. Preferably, the rules for active buffer management are different for drop and no drop VLs.