What will FCoE mean for the Cisco MDS?

Cisco has already announced the new Supervisor-2B which advertises support for FCoE on the Cisco MDS.  But what does that mean exactly?  I don’t know for sure, because there really isn’t much information on Cisco to document the FCoE capabilities of this supervisor.  The tech note eludes to an “FCoE module” of some sort that will be required for FCoE functionality.

Cisco MDS Supervisor-2A

It is pretty clear that the MDS will not support FCoE initiators to connect directly to it.  That job is already handled very well by the Nexus 5k/2k.  The Nexus switches can also terminate FCoE targets as well, so I am not sure what the advantage would be to having some sort of FCoE target module since those could just be connected to the Nexus.  A capability that would seem most likely is that the MDS will be able to share its FC storage via FCoE.  This type of functionality already exists on the MDS for iSCSI.

The main benefits of FCoE in a typical network are on the initiator side.  That is wear 80% or more of the benefits are.  The risk/difficulty today in an FCoE world is the lack of pervasive DCB switching and storage supporting FCoE directly.  By terminating initiators using CNA’s into Nexus switches, but leaving your storage on FC, you gain almost all the benefits and take on very little obstacles that one may face when trying to deploy an end-to-end converged network.  This is also where the savings are from a financial perspective.  For this reason I can see the MDS FCoE module as a useful option.  On the flip side is the fact that there are many companies producing front end units that will share out heterogenous storage using FCoE.

All we can do for now is wait and see what Cisco releases on the order of documentation and hardware to support FCoE on the MDS.  It is unfortunate that a new Supervisor seems to be required and likely an additional module, hopefully there are some good features and functionality that will come out of its use.

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