What is Fibre Channel over Ethernet (FCoE)?

As the use of Storage Area Networks in Datacenters continues to grow, new technologies emerge as possible cost-effective solutions. One of them is Fibre Channel over Ethernet or FCoE. Fibre Channel over Ethernet is a networking technology that simplifies the network architecture by combining both Storage Area Network (SAN) and Local Area Network (LAN) onto a single 10GB/s link. This technology can simplify the infrastructure by needing less storage interfaces, reduced cable infrastructure and unified switching architecture and eventually would lead to lower power consumption.

The transmission of the data traffic with this technology requires the encapsulation of native Fibre Channel frames into Ethernet packets. This solution allows the leading IT companies to maintain the existing latency and security as before implementing this solution. The Fibre Channel over Ethernet frame is encapsulated into Ethernet packets with the help of a dedicated Ethertype 0x8906. This solution uses lossless Ethernet fabric and its own frame format.

The key difference between Fibre Channel over Ethernet and the traditional Fibre Channel is the fact that the traditional Fibre Channel protocol has five layers, known as FC-0, FC-1, FC-2, FC-3 and FC-4. The first two, FC-0 and FC-1, represent the physical and data layers and these are the ones replaced in a Fibre Channel over Ethernet solution by the traditional Ethernet OSI model layers, the physical and MAC address layer.

The main issue for the architects developing this solution was to find a way around the lossy characteristic of the traditional Ethernet. They managed to do this with the help of a feature of the Ethernet that enables the receiving port to send a pause request to the sending port if it’s too busy to receive data. Another feature is the implementation of a priority flow control feature which enables these pause capabilities of Ethernet to be merged with quality of service capabilities. These features would guarantee that all of the data sent would arrive on the receiving end.

The main advantage of deploying this technology is the simplified infrastructure. This means that there is no need to install and maintain a large number of cables, network adapters and switch ports. This is shown in the table below comparing a network of 8 servers that use redundant network interfaces for SAN and LAN and a Fibre Channel over Ethernet solution end to end:

In addition, another big advantage of this technology is the simplified process of day to day maintenance and tasks in the server room, at the same time allowing for new servers to be installed quicker and easier. The smaller number of network adapters, cables and switches results in lower power consumption. For example, each Fibre Channel HBA (Host Bus Adapter) consumes around 13 watts of power, while a standard Fibre Channel switch consumes around 70 watts. The power consumption is also reduced by the reduced cooling equipment. From the table above, it’s estimated that for this type of network rack the savings may be up to 200 watts from the removal of the unneeded HBAs from each of the 8 servers and 70 watts from the removal of one unneeded switch. This is multiplied by thousands in a typical Datacenter environment due to the high number of networking devices. As the leading IT companies are constantly pushing other companies to “go green” and save the environment, these power savings would always be welcomed.

The Fibre Channel over Ethernet solution has been designed from the ground up to allow for maximum flexibility and simplified network deployment and management. Backed up by the IT leaders Cisco and Intel and with the new and innovative network devices emerging on the market, building future Datacenters have never been simpler than today.