Converged networks with Fibre Channel over Ethernet and Data Center Bridging

Figure 1: The various attempts at converged infrastructure produced multiple protocol stacks.

Fibre Channel InfiniBand FCoE/DCB

Internet SCSI (iSCSI) was an attempt to bring a direct SCSI to TCP/IP mapping layer and protocol to the

mass Ethernet market. Proponents of iSCSI wanted to drive down cost and to deploy SANs over existing

Ethernet LAN infrastructure. iSCSI technology (Figure 1, blue shaded oval) 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 of devices

using FC interfaces. Also, iSCSI to FC gateways and routers are 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, red shaded

oval). 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 lets Ethernet-based hosts attach to FC SANs

through iFCP-to-FC SAN gateways. These gateways and protocols were not widely adopted except for SAN

extension because of their complexity, lack of scalability, and cost.

10 Gigabit Ethernet

One obstacle to using Ethernet for converged networks has been its limited bandwidth. As 10 Gigabit

Ethernet (10 GbE) technology becomes more widely used, 10 GbE network components will fulfill the

combined data and storage communication needs of many applications. As Ethernet bandwidth increases,

fewer physical links can carry more data (Figure 2).