A Fibre Channel over Ethernet primer

Find out why Fibre Channel over Ethernet seems compelling for so many IT pros. Scott Lowe outlines FCoE's benefits and the challenges data center architects need to consider before adopting the protocol.

Today's new Ethernet networks still bear a significant resemblance to the first Ethernet networks deployed based on the February 1980 ratification of the original 802.11 standard. You could say today's Ethernet networks are the homo sapiens of the Ethernet world when compared to the Neanderthal Ethernet of the past; another way to think of it is that Ethernet has evolved, but its DNA has remained solid and functional. This is why many data center architects have eschewed other communications transport mechanisms in favor of this stalwart technology.

One needs to look no further than iSCSI to see significant uses of Ethernet (really, iSCSI uses TCP/IP, but most often riding on Ethernet) in places other than traditional networking applications. Fibre Channel is able to bring high-end storage capability to the masses at more affordable prices by jettisoning complex architectures for more simplistic ones based on an enhanced Ethernet.

Here's an overview on why Fibre Channel over Ethernet (FCoE) seems compelling for so many IT pros. In an upcoming more technical column, I'll focus on what makes FCoE tick.


FCoE has a host of business and technology-focused benefits, which include:

  • Less overhead when compared to iSCSI. iSCSI uses TCP/IP (again, generally on Ethernet) as its communications transport, so there is significant overhead involved in encapsulating the SCSI commands into TCP/IP packets, which must then be converted to Ethernet frames before being sent out on the wire. FCoE encapsulates traditional Fibre Channel frames directly into Ethernet frames, eliminating one major step from the communications equation. In the case of FCoE, Fibre Channel is just another networking protocol riding atop the Ethernet highway alongside other protocols, including TCP/IP.
  • Leverages advances in an existing technology. More and more networks are using 10 Gbps-based Ethernet, and 40 Gbps and 100 Gbps standards were ratified in June 2010, ensuring that the Ethernet platform has years of life left in it. The advent of 10 Gbps Ethernet is what made the leap from traditional Fibre Channel to FCoE possible, as Ethernet has attained the performance characteristics necessary for these kinds of workloads.
  • Simplifies the storage skill set. Ethernet is practically everywhere, though traditional Fibre Channel is not. While FCoE will still require some proprietary skills, the transport mechanism is very common in the data center.

More importantly, FCoE can help businesses solve real-world problems, which include:

  • Lowering costs. With the need for fewer cables and networking devices, not as much power is consumed, which means organizations will save money. FCoE-based networks can use a converged network adapter (CNA) that supports TCP/IP and FCoE so that a single NIC can support both protocols. This results in simplified I/O. In terms of networking hardware, newer network switches, such as the Cisco Nexus 5000, support FCoE traffic on all 10 Gbps ports, thereby reducing (or eliminating) the need for a side-by-side storage/networking architecture.
  • Modifying skill sets. I mentioned before that FCoE requires a somewhat simplified skill set. From a hiring and staffing perspective, this can translate into lower overall costs. It may also help IT redirect staffing resources to higher profile projects.
  • Interoperability. If your business already has substantial investments in traditional Fibre Channel gear, there are FCoE to Fiber Channel gateways available to provide seamless integration.


These are some things to keep in mind with regard to FCoE:

  • There's more to convergence than cables. In IT, there are usually storage teams and networking teams and never the two shall meet... except when their worlds collide. With any new technology, there will be adoption hurdles and unanticipated challenges, but the adoption of FCoE will require very close cooperation between all of the teams involved.
  • You have to troubleshoot two networks instead of one. In a converged network, the very act of convergence adds new complexity that may not have been inherent in the traditional communications silos; now any networking issue can compromise both sets of services. This tradeoff must be considered when making the decision to aggregate these kinds of resources.
  • It's a new Ethernet day. FCoE relies on Enhanced Ethernet (also referred to as Converged Enhanced Ethernet or Data Center Ethernet), which adds new capabilities to Ethernet (I'll discuss those capabilities in my next article about FCoE). In order to leverage these enhancements to the Ethernet, the network hardware supporting the infrastructure must support it. I mentioned that Cisco Nexus 5000 switches do so, but not all vendors have made this leap.


When you consider the potential for reduced costs and a smaller carbon footprint, FCoE might be just what the CIO ordered when it comes to your next data center architecture.

Keep up with Scott Lowe's posts on TechRepublic