Fibre Channel over Ethernet Traffic

What constitutes a market? Really, take a moment to think about it. Done?

I’ve been asking myself this question for the past several weeks. Seems like I run into a new glassy-eyed IT guy that has heard the words "Fibre Channel over Ethernet" and they’ve been swept off their feet. Sure, I like the sound of running just one network – and Ethernet has proven time and again it is the dominant technology. So I started to look behind the curtain at FCoE to see what is really there.

Colleagues that have sat through briefings tell tales of product lines that will unify the data center, cure cancer and stop world hunger! After taking a closer look the best analogy that comes to mind is Dorothy looking behind the curtain of the Wizard of Oz. The grandness of vision at first glance evaporates when you scratch the surface. How disappointing it is to see that there are only two vendors, each with a single switch. I was expecting product lines, not a product. I was expecting broad adoption, choice! Where is the great FCoE vision?

Well it turns out the vision is in the future, more specifically in several IEEE working groups. You see, the only standard ratified so far is the encapsulation of Fibre Channel in Ethernet – it even has its own Ethertype. Isn’t this FCoE many ask? Yes and no.

It is important to realize that putting Fibre Channel into Ethernet packets is just the first part of the solution. There are many other pieces required for Ethernet and FCoE to displace today’s storage network. Fibre Channel is pretty finicky; it mandates ‘lossless Ethernet’. Today’s Ethernet isn’t lossless, and follows its original design as a ‘best efforts’ transport. There is an effort to transform Ethernet into a data center bridging medium, capable of supporting FCoE.

Currently the IEEE has several work groups (e.g. P802.1Qau, P802.1Qbb, P802.1az among others) that are developing the necessary standards (yes that’s a plural) required for Ethernet to be a viable transport layer for Fibre Channel traffic. Within each of these work groups there is a lot of work to be completed. The transformation of Ethernet from "best efforts" to "lossless" is not a small challenge, although vendor briefings I’ve sat through have ignored this. The current estimate of completion is in the latter half of 2011. So should I put an end-to-end data center fabric on my Christmas wish list for 2011?

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If I did, I think I’d be disappointed. The standards work to be completed will likely have some early draft adopters, but considering the data center is the heart of a company I wouldn’t budget any dollars for this before 2012. Looking at prior standards, there is a gap from when a standard is approved and when standards-based products will likely become available from multiple vendors – providing choice and stability. So given that we’re really looking at two years before FCoE is viable, would I try any products now?

Let’s look at the benefits. Suppose you have today a top of rack switch that has 10GbE Converged Ethernet interfaces and Fibre Channel uplinks. Server traffic destined for various networks would be split at this switch and forwarded to the network it is destined for; Fibre Channel over Ethernet traffic would egress the Fibre Channel interfaces and the data traffic would egress the Ethernet interfaces. FCoE traffic would cease to be FCoE. It would be translated at the very first switch into native Fibre Channel.

 

Yes, I could reduce the number of interfaces in my servers to a single adapter (likely two for redundancy), but is that enough to take the plunge? Not for my network. I already have Fibre Channel run to my servers and even though we replace servers routinely – especially as we virtualize systems to reduce our footprint – there just isn’t a large enough benefit to reducing what is essentially the first five feet of a storage network.

Instead, we’ve made a decision to migrate to iSCSI storage and reduce the systems using our Fibre Channel SAN. We’re already gaining benefits of a converged network without the risk of integrating incomplete solutions. I won’t risk the religious argument of FCoE vs. iSCSI in this post, but am interested in covering that in the future.

Knowing every site is unique – what are your plans for a converged data and storage network?

Mark Townsend

About Mark Townsend

Mark Townsend's career has spanned the past two decades in computer networking, during which he has contributed to several patents and pending patents in information security. He has established himself as an expert related to networking and security in enterprise networks, with a focus on educational environments. Mark is a contributing member to several information security industry standards associations, most notably the Trusted Computing Group (TCG). Townsend's work in the TCG Trusted Network Connect (TNC) working group includes co-authoring the Clientless Endpoint Support Profile. Townsend is currently developing virtualization solutions and driving interoperability testing within the industry. Prior to his current position, he has served in a variety of roles including service and support, marketing, sales management and business development. He is considered an industry expert and often lectures at universities and industry events, including RSA and Interop. Mark is also leveraging his background and serving his community as Chairman of the local school board, a progressive school district consistently ranked in the top school districts of New Hampshire, with the district high school ranked as a "Best High School" by US News & World Report.

2 Responses to Fibre Channel over Ethernet Traffic

  1. Seth F February 17, 2010 at 12:58 pm #

    Hi Mark!

    While I see that this article is true on February 17 2010, it may not be the case in a few months. You see, many vendors – Cisco, Brocade, QLogic, Blade, Emulex – have already started shipping FCoE solutions to their customers and OEMs – IBM, HP, EMC, Hitachi, Netapp, Dell to name a few. This include ToR, MoR, and EoR options as well as a slew of CNAs for server connectivity.

    It is a single box today but if you look at the vision for the technology, there are a couple of key points I think are missing.

    1. This single box is only one option. Both Cisco and Brocade have established fibre channel chassis with FCoE available as a blade in the Brocade model. As for Cisco, they have planned FCoE on the Nexus for quite some time. So, while the standards haven’t caught up just yet, there is an option at the aggregation layer of data centers while still retaining investment in the FC backbone.

    2. iSCSI while a viable option cannot be the de facto alternative to FC. It just won’t be trusted considering it’s not lossless.

    3. The standards mentioned in the article pretty much equate to TRILL. While this is yet to be a final product, it WILL BE a game changer for the adoption rate of FCoE. It will serve as the point in which you can connect targets across a true IP/ethernet backbone with multiple hops.

    So, while I can agree that FCoE is not yet ready, many people have been deploying the technology at the aggregation layer with more and more interest as the technology matures. Let’s face it…Ethernet wins every time. Look at SNA, token ring, FDDI, etc…

    My prediction is that these enablement technologies will be rolled into hardware people are already using with minimal impact to their investments. As people migrate and accelerate towards VM, why not get that new blade center chock full of FCoE ports and use that new server with FCoE ToR or chassis based solutions from the #1/2 vendor in the market for FC?

    There will be an inflection point somewhere in the not too distant future where this will occur. ……IMO

  2. Mark Townsend
    Mark Townsend March 12, 2010 at 2:16 pm #

    Seth,

    You definitely offer some view points, but the analyst community is starting to take a long hard look at iSCSI as a technology today that is not only viable, poses serious questions regarding FCoE’s future.

    In Frank Berry’s Feb 19 blog (Network Computing), Frank talks about Intel/Microsoft’s overhaul of iSCSI. Result? 1 million IOPs per second with MS Server 2008 R2 using 1Gbps Ethernet. To put that in perspective that is twice the IOPs capable with 8Gbps FC.

    Frank is not the only analyst talking highly of iSCSI. Network Computing Editor Mike Fratto’s Feb 23 article “Break the Storage Racket” recommends iSCSI to replace Fibre Channel.

    FCoE does provide a migration path for existing FC SAN customers, but even FC SAN vendors are offering iSCSI heads for their existing SAN gear.

    If I were designing a data center for today, I’d seriously consider implementing iSCSI SAN. The performance is there, the security is there (choose wisely) and more importantly you can run it across existing Ethernet equipment without limitations.

    iSCSI will even benefit from future IEEE standards for data center bridging.

    Thanks for your comment!

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