Transporting Fibre Channel Over Ethernet

What is this patent about?

’077 is related to the field of data communication, specifically bridging the gap between Ethernet-based Local Area Networks (LANs) and Fibre Channel-based Storage Area Networks (SANs). Traditionally, these networks have been separate, requiring servers to have connections to both, leading to increased complexity and cost. The patent addresses the need for a unified network architecture that allows SAN devices to be accessed using Ethernet technology.

The underlying idea behind ’077 is to encapsulate Fibre Channel frames within Ethernet frames, enabling the transport of Fibre Channel data over Ethernet networks. This is achieved by a Fibre Channel over Ethernet (FCoE) Transformer that converts FCoE protocol to the Fibre Channel FC-1 protocol and vice-versa. The key insight is to map Fibre Channel's start-of-frame (SOF) and end-of-frame (EOF) delimiters into fields within the FCoE transport header, allowing Ethernet switches to forward the data without needing to understand the Fibre Channel protocol.

The claims of ’077 focus on a method, a transformer, and a system for operating a Fibre Channel over Ethernet (FCoE) environment. Specifically, the claims cover receiving an FCoE frame at the FCoE Transformer via a Layer 2 Ethernet switch, converting the FCoE frame to a Fibre Channel frame, and transporting the Fibre Channel frame. The FCoE transport header includes fields for encoding the SOF and EOF characters of the Fibre Channel frame.

In practice, the FCoE Transformer acts as an intermediary between the Ethernet and Fibre Channel networks. When an FCoE frame arrives, the transformer extracts the Fibre Channel frame, using the SOF and EOF fields in the FCoE transport header to reconstruct the original Fibre Channel frame. This frame is then transmitted over the Fibre Channel network. Conversely, when a Fibre Channel frame is received, the transformer encapsulates it within an FCoE frame, placing the SOF and EOF characters into the appropriate fields in the FCoE transport header. The resulting FCoE frame is then sent over the Ethernet network.

This approach differs from prior solutions that involve running storage protocols over TCP/IP, such as iSCSI or FCIP. These IP storage solutions require TCP offload engines and associated support logic, increasing implementation costs. ’077, by operating at the MAC layer, avoids the overhead of TCP/IP, allowing existing Ethernet infrastructure to be used for SAN connectivity without requiring intermediate network devices to be aware of Fibre Channel data stream specific information. The FCoE header contains all the information needed to select the appropriate Ethernet and Fibre Channel ports, simplifying the process.