Transporting fibre channel over ethernet

What is this patent about?

’591 is related to the field of data center networking, specifically the convergence of Storage Area Networks (SANs) and Local Area Networks (LANs). Traditionally, these environments rely on distinct hardware: Fibre Channel for high-performance storage traffic and Ethernet for general-purpose communication. This dual-infrastructure approach leads to high costs, management complexity, and interoperability challenges, as Fibre Channel requires specialized switches and host bus adapters that are significantly more expensive than their Ethernet counterparts.

The underlying idea behind ’591 is to eliminate the need for a physical Fibre Channel infrastructure by transporting Fibre Channel data frames and primitive signals directly over Ethernet at the MAC layer. By bypassing higher-layer protocols like IP, UDP, or TCP, the invention avoids the overhead and expense of TCP offload engines. The core insight is that the essential control information of Fibre Channel—such as frame delimiters and link-level signals—can be mapped into a specialized Ethernet payload, allowing standard Ethernet switches to function as a transparent transport for storage traffic.

The claims of ’591 focus on a method for converting between Fibre Channel and Ethernet frames using an FCoE Transformer. This hardware or software component encapsulates a Fibre Channel frame into an Ethernet frame without utilizing an IP packet. Crucially, the claims require the Ethernet-based FCoE frame to include specific fields that encode the Start of Frame (SOF) and End of Frame (EOF) characters. These fields ensure that the class of service and frame boundaries of the original Fibre Channel data are preserved when the transformer reconstructs the frame for delivery to a legacy Fibre Channel device.

In practice, the system utilizes an FCoE Host Bus Adapter in the server to generate virtualized Fibre Channel traffic, which is then routed through standard Layer 2 Ethernet switches. The FCoE Transformer acts as a bridge, translating these specialized Ethernet frames back into native FC-1 and FC-0 protocols for storage devices. This architecture supports fragmentation and reassembly, allowing large Fibre Channel frames to be split across multiple Ethernet packets while maintaining data integrity through unique FCoE identifiers and offset fields.

This approach differentiates itself from prior art by operating strictly at Layer 2, removing the complexity of IP-based tunneling protocols like iSCSI or FCiP. Unlike earlier solutions that were limited to one-to-one port mappings, the ’591 invention uses an Interface Port Identifier within the FCoE header to support multiple Fibre Channel and Ethernet interfaces simultaneously. This allows a single transformer to manage complex associations between virtualized server ports and physical storage targets, effectively unifying the data center fabric onto a single, cost-effective Ethernet medium.