Converged networks with Fibre Channel over Ethernet and Data Center Bridging

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IB-centric protocols/networks to the native FC storage devices in data centers. High Performance Computing
(HPC) environments that have adopted IB as the standard transport network use SRP and iSER protocols.
Figure 1. Comparison of multiple protocol stacks for converged networks
Fibre InfiniBand FCoE/DCB
Channel
Internet SCSI (iSCSI) was an attempt to bring a direct SCSI to TCP/IP mapping layer and protocol to the
mass Ethernet market, to drive costs lower, and to allow deploying SANs over existing Ethernet LAN
infrastructure. iSCSI technology (Figure 1, center) was very appealing to the small and medium business
market because of the low-cost software initiators and the ability to use any existing Ethernet LAN.
However, iSCSI typically requires new iSCSI storage devices that lack the features in devices using FC
interfaces. Also, iSCSI to FC gateways and routers are very complex and expensive. They do not scale cost
effectively for the enterprise. Most enterprise businesses have avoided iSCSI or have used it for lower tier
storage applications or for departmental use.
FC over IP (FCIP) and Internet FC Protocol (iFCP) map FCP and FC characteristics to LANs, MANs, and
WANs. Both of these protocols map FC framing on top of the TCP/IP protocol stack (Figure 1, right of
center). FCIP is a SAN extension protocol to bridge FC SANs across large geographical areas. It is not for
host/server or target/storage attachment. The iFCP protocol allows Ethernet-based hosts to attach to FC
SANs through iFCP-to-FC SAN gateways. These gateways and protocols were never widely adopted except
for SAN extension because of their complexity, lack of scalability, and cost.
Network convergence with FCoE
FCoE is the next attempt to converge block storage protocols onto Ethernet. FCoE relies on an Ethernet
infrastructure that uses a new set of Data Center Bridging (DCB) standards defined by the IEEE (Figure 1,
right). Converged Enhanced Ethernet (CEE) is Ethernet infrastructure that implements DCB. Although the
DCB standards can apply to any IEEE 802 network, most use it to refer to enhanced Ethernet, making DCB