Blog on June 25, 2010
At the latest meeting of the T11.3 standards organization (FC-BB-6 Ad Hoc Working Group) the concept of FCoE Direct End-to-End protocol was accepted for input into the Workgroup's next standard. It is also known as FCoE VN_Port to VN_Port (FCoE VN2VN). This new function permits FCoE adapters, which are interconnected within the same Level 2 Lossless Ethernet network, to discover and connect to compatible FCoE adapters -- which have the appropriate Virtual N_Ports -- and then transmit Fibre Channel commands and data via the standard FCoE protocol.
This is all done on a Lossless Ethernet Network without any assistance from a Fibre Channel Switch or an FCoE Switch (called an FC Forwarder -- FCF). All that is needed is the appropriate VN2VN FCoE Adapters and a Lossless Ethernet layer 2 Network.
There also exists, today, some Open Source FCoE software that only requires a normal Ethernet NIC, to operate standard FCoE protocols (a special Converged Network Adapter -- CNA -- is not required). It is expected that this Open Source software will be updated to also support the new VN2VN function.
The VN2VN (direct End-to-End) function will support 2 types of direct connections:
1. Connections through Lossless Ethernet switches
2. One to One Connection via a single cable (point to point)
The FCoE protocol is made up of 2 types of Ethernet frames (which have their own unique Ethertypes):
1. The FCoE initialization Protocol (FIP) frame packets
2. The Fibre Channel over Ethernet (FCoE) frame packets
The FIP packets are only used as part of discovery and connection setup whereas the FCoE packets carry the actual FC commands and data. The new VN2VN functions have only added additional FIP packets, and have left the rest of the protocol unchanged. The new VN2VN FIP packets were needed since in this mode there is no FCF to provide connection services.
The transfer of FC data and commands via the FCoE protocol -- which was developed in the T11.3 standards organization (FC-BB-5 Ad Hoc Working Group) -- continues to operate as currently specified and will continue unchanged in this new VN2VN environment.
The upper levels of the protocol remain FC, and that means that there continues to be complete compatibility with existing FC & FCoE Device Drivers etc. The vendors are, of course, adding additional management capabilities to exploit the additional capabilities of FCoE, but the command and data protocol do not require any modifications. Likewise, as adapters are updated to support VN2VN mode, the upper layers will retain their current FC compatibility even as additional management capabilities are added to permit ease (and flexibility) of use.
This new VN2VN capability will permit FC protocol to go "Down Market" to entry and Mid Range environments. Yet, as the installation grows it will be able to install FCF switches and thereby obtain the additional functions of a FC network without having to change the server or storage connections.
The new VN2VN capability will be competitive to iSCSI within a Data Center Environment. And I fully expect the Lossless Ethernet Standards, which were focused at a 10Gb/s Ethernet, to be offered by various vendors on 1Gb/s networks and switches. This will mean that FCoE VN2VN will operate very well with the Open Source FCoE code and 1Gb/s NICs without the overhead of TCP/IP. This should make the FCoE VN2VN capability very performance competitive with iSCSI.
Stay tuned to this Blog to see how the capability unfolds.
Friday, June 25, 2010
Wednesday, January 13, 2010
FCoE Adapter Based Shortcuts
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.
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.
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