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Archie Hendryx

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Storage: Blog Post

2010 and the Re-emergence of FCoE

The benefits of FCoE maybe just too hard to ignore

Advocates of FCoE will immediately mention the benefits of simplified network management, elimination of redundant cabling & switches, reduced power and heat requirements, alongside enhanced data network performance yet despite that still today the FCoE revolution failed to take place. But as the enhancement of Lossless Ethernet begins to really take shape with its promise of a non requirement for TCP/IP overheads, CEE / DCE / EEDC are now looking like viable transports for storage traffic and storage fabrics.

From the moment 10 Gigabit Ethernet became a reality to the mainstream, the emergence of FCoE was a mere formality. Encapsulating Fibre Channel frames over Ethernet networks, FCoE offered the possibility of allowing Fibre Channel to use Ethernet networks while preserving the Fibre Channel protocol. With speeds close to Fibre channel, FcoE now offers companies a tempting cost effective alternative which would support both FC and Ethernet traffic over a single physical infrastructure. Hence storage and network traffic over a single set of cables, switches, and adapters, thus saving in the complexity of managing two physical networks and consequently saving on energy consumption and heat generation.

Furthermore by replacing the FC0 and FC1 layers of the Fibre Channel stack with Ethernet, FCoE allows seamless integration with existing Fibre Channel networks and management software due to the FCoE protocol specification retaining the native Fibre Channel constructs. Hence it comes as no surprise of the news that many vendors are now seriously developing marketing strategies and products which will incorporate the latest and supposedly improved versions of the FCoE standards.

As well as the SAN switch boys Brocade, Cisco and QLogic, vendors such as Emulex, Intel, PMC-Sierra, NetApp and EMC are all looking to develop and market FCoE with new FC and FCOE switches as well as CNAs. Indeed it is the CNAs (Converged Network Adapters) which are the magic behind enabling the connection between the host and FCoE by containing both the functionality of a FC Host Bus Adapter (HBA) and Ethernet NIC on the same adapter.

But FCoE does come along with certain snags as well the obvious one of not being as secure as FC. Firstly load balancing and thus optimal resource utilisation is still an issue due to Ethernet being a Layer 2 protocol and thus leaving FCoE to be unroutable. Hence currently multipathing is still not an approved option. Ironically the problem arises from the advantage FCOE presents with the disbandment of using both Ethernet for TCP/IP networks and Fibre Channel for storage area networks, in favour of one unified network. With Fibre Channel running on Ethernet alongside traditional Internet Protocol (IP) traffic, thus becoming just another network protocol, FCoE operates directly above Ethernet in the network protocol stack, in contrast to iSCSI which runs on top of TCP and IP. Therefore as a result of this FCOE will fail to function across routed IP networks as it is unable to be routed at the IP layer.

Another concern is that once the marketing hyperbole of 10-Gbit is brushed away the truth that remains is that any storage traffic initialised at 10-Gbit will still get dropped onto an 8Gb native FC SAN or 4Gb in the case of most Cisco and Qlogic switches. This becomes more of a point to raise when put in the context that the Fibre Channel Industry Association (FCIA) are showcasing roadmaps for FC which designate that FC will advance from 4->8->16->32 gigabit.

Despite this in an economic climate in which consolidation and cost effectiveness have become keywords, FCOE may be the option that once developed, tested and proven in the mainstream; most customers will be looking to scale out to. With the ability to not only reduce the NICs needed to connect disparate storage and IP networks but also the number of cables and switches as well as the power and cooling costs, FCoE's benefits could well be an option that most companies will now find hard to ignore.

More Stories By Archie Hendryx

SAN, NAS, Back Up / Recovery & Virtualisation Specialist.