Recently there has been a movement within the T11.3 standards organization (FC-BB-6 AdHoc Working Group) to define a method for letting FCoE (Fibre Channel over Ethernet) Host Storage Adapters, called CNAs (Converged Network Adapters), send messages and data directly to Peer Storage Adapters without passing through a Fibre Channel (FC) Switch or an FCoE Switch -- called a Fibre Channel Forwarder (FCF). This work is part of the follow-on efforts that have been based on the recently approved Fibre Channel over Ethernet (FCoE) Standard. In this FCoE Standard it is possible for Fibre Chanel Protocols (FCPs) to flow on a Lossless Ethernet Network. (Refer to www.Hufferd.com and the slide presentation at the End of the Web Page for additional details on this FCoE technology.)
I posted a previous Blog Called "New Extensions for Fibre Channel over Ethernet (FCoE)" which gave folks a send ahead of this new direction.
Since that posting there has been a great deal of movement on this front. The author has made a number of proposals (to the T11 FC-BB-6 AdHoc Working group), as have others. At this moment the actions have been coalescing around two related but unique approaches (both proposed by this author). One approach (nicknamed "Adapter Based Shortcuts" -- ABS) that was described in the previous Blog ("New Extensions ….") that involves an FCoE Switch (aka FCF) but only for connection setup etc. and then permits direct Adapter-to-Adapter data and message transfer. The other approach (nicknamed "direct-mode Adapter Based Shortcuts" -- dABS) enables FCoE Adapters (CNAs) to send messages and data to each other without any involvement of an FCoE Switch (FCF).
The value of both of these proposals is that Fibre Channel technology can go "down market" to installations that do not have any significant training on Fibre Channel. The dABS proposal can be used in small installations that need a SAN (Storage Area Network) and only need to have the appropriate Converged Network Adapters -- which supports both IP and FCP on Ethernet -- and the new Lossless Ethernet Switches. The ABS proposal requires (in addition) at least a small (maybe 4 ports) FCF Switch for managing the connection process, Zoning protection, etc. (but some FCFs include the Lossless Ethernet Switches as part of the FCF and this holds down the cost and simplifies the overall installation).
Since FCFs are designed to interconnect with normal Fibre Channel switches, or perform all the Fibre Channel functions on Lossless Ethernet, one can see how it might be possible for a small installation to begin with the dABS approach and over time move to an ABS approach and as the installation continues to grow ultimately embrace a full FCoE or FC Fabric with all the services of Fibre Channel (including Hard Zoning, Virtualization of Storage Controllers, Encryption at Rest, etc.)
However, even if these approaches are compatible with each other and together permit an easy growth path, the T11 Standardization Committee might not want to pursue both approaches. In that case either the dABS or the ABS approach will probably be accepted.
Stay tuned to this Blog for the results as the smoke begins to clear.
