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Fibre Channel Over Ethernet: From Fee To Free
alphadogg writes "With demand for Fiber Channel over Ethernet (FCoE) more sluggish than vendors had hoped, 10 Gigabit Ethernet switch and adapter makers are making it available for free. FCoE is a standard driven largely by Cisco to converge customers' data center LAN and storage fabrics with 10G Ethernet. Industry heavyweights Intel and Brocade are among those now giving away FCoE capabilities. There are several factors prompting vendors to slash FCoE prices or stop charging for it altogether, including market indifference; technological immaturity; competing alternatives, such as virtualized Fibre Channel and Ethernet I/O; the recession; and vendors looking to drive switch volumes. 'When FCoE first came out there used to be a fairly large price premium,' says Alan Weckel, director of Dell'Oro Group. 'Cisco had to give it away for free to drive switch volumes. Users were not adopting as rapidly as thought or that Cisco had hoped for.'"
Actually, FC isn't routable. FC over *ethernet* has no ip and no provisions to span gateways. The *theory* is that FCoE has fewer layers allowing for higher performance, but it's rare for that difference to be realized in cheap ethernet fabrics (the whole point of FCo*E*) and even rarer to matter relative to storage device performance limitations. iSCSI is much easier to manage with fewer limitations and gets some nice things from being over TCP whether FCoE people will admit it or not.
When FCoE first came to market, vendors had dollarsigns in their eyes with thoughts of extorting customers with FC pricing strategies using 'just' ethernet. You saw people trying to do per-port FC enablement licensing BS and other stuff unheard of in ethernet land.
If FCoE is going to exist long term, it will be as a 'freebie' alternative to iSCSI or as a convenience to build large SANs without a lot of FC switches and HBAs but using existing FC enclosures.
XML is like violence. If it doesn't solve the problem, use more.
Apparently the latter. "Since classical Ethernet has no flow control, unlike Fibre Channel, FCoE requires enhancements to the Ethernet standard to support a flow control mechanism (this prevents frame loss). . . . Fibre Channel required three primary extensions to deliver the capabilities of Fibre Channel over Ethernet networks: -Encapsulation of native Fibre Channel frames into Ethernet Frames. -Extensions to the Ethernet protocol itself to enable an Ethernet fabric in which frames are not routinely lost during periods of congestion. -Mapping between Fibre Channel N_port IDs (aka FCIDs) and Ethernet MAC addresses." --Wikipedia
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Your plain-vanilla 10GbE switch does not have the flow-control bits required to make Ethernet lossless; without essentially lossless traffic, SCSI/FC perf goes in the dumpster. (0.03% packet loss == approx. 50% performance cut.)
In addition, there must be at least one switch in the VLAN that can provide FC services, such as zoning, address assignment, name services, etc.