Transporting Fibre Channel Over Ethernet

What is this patent about?

’473 is related to the field of data communication, specifically the transport of Fibre Channel (FC) data over Ethernet networks. Traditionally, Storage Area Networks (SANs) relied on Fibre Channel, while Local Area Networks (LANs) used Ethernet. This required separate infrastructures. The patent addresses the problem of converging these networks by enabling Fibre Channel communication over existing Ethernet infrastructure, potentially reducing cost and complexity.

The underlying idea behind ’473 is to encapsulate Fibre Channel frames within Ethernet frames, allowing them to be transmitted over a standard Ethernet network. This is achieved by adding a FCoE transport header to the Ethernet frame. This header contains fields that encode the Start of Frame (SOF) and End of Frame (EOF) delimiters, which are essential for proper Fibre Channel frame delineation but are typically external to the data frame in native Fibre Channel.

The claims of ’473 focus on a Fibre Channel over Ethernet Host Bus Adapter (FCoE HBA) and a method for its operation. The FCoE HBA connects to a standard Ethernet switch and sends FCoE frames. These frames contain a FCoE transport header that encapsulates the Fibre Channel frame. Crucially, the FCoE transport header includes fields for encoding the SOF and EOF delimiters of the Fibre Channel frame, enabling the Ethernet network to correctly interpret and forward the Fibre Channel data.

In practice, the FCoE HBA takes a Fibre Channel frame, encapsulates it within an Ethernet frame using the defined FCoE transport header, and transmits it over the Ethernet network. A receiving device, such as an FCoE switch or another FCoE HBA, decapsulates the Fibre Channel frame from the Ethernet frame using the SOF and EOF fields in the FCoE transport header. This allows Fibre Channel devices to communicate over Ethernet without requiring changes to the underlying Ethernet infrastructure.

This approach differs from prior solutions that might have involved IP-based storage protocols, which often require TCP offload engines and are more complex to implement. By operating at the Ethernet MAC layer and directly encapsulating Fibre Channel frames, ’473 aims for a more efficient and lower-overhead solution for converging SAN and LAN traffic. The use of the SOF and EOF fields within the FCoE transport header is key to maintaining Fibre Channel frame integrity during transport over Ethernet.