Fibre Channel Over Ethernet - HP N1200 - StorageWorks Network Storage Router Brochure

Figure 2. Message exchange between an initiator and target using the iSCSI protocol mode
Initiators include software initiators and HBAs. Software initiators require CPU resources to manage
the protocol stack. A more efficient approach is to offload protocol management to an iSCSI HBA,
such as the HP NC373i Integrated Multifunction Gigabit server adapter.
iSCSI allows Ethernet server adapters to function both as network adapters and as storage HBAs. This
flexibility provides access to storage boxes and to servers over a single connection, which simplifies
network infrastructure. HP multifunction adapters support hardware-assisted, or accelerated iSCSI
operation―that is, offloading the iSCSI software to the server adapter for improved system
performance.

Fibre Channel over Ethernet

FCoE is an emerging technology being developed by the International Committee for Information
Technology Standards (INCITS) T11 technical committee. FCoE relies on flow control to recognize that
a buffer is almost full and to request that the sender stop transmission until the buffer has emptied and
transmission can start again. FCoE is based on Enhanced Ethernet (EE), sometimes referred to as Data
Center Ethernet (DCE) or Converged Enhanced Ethernet (CEE). The Institute of Electrical and
Electronics Engineers (IEEE) is working to enhance the IEEE 802 Ethernet standard to allow FC to run
efficiently over Ethernet. Two recent Ethernet improvements are lossless Ethernet, which prevents lost
packets, and pause-based flow control, which allows the network to selectively pause different classes
of traffic.
FCoE encapsulates Fibre Channel (FC) frames within the Ethernet fabric and uses the same Open
Systems Interconnection (OSI) layer as IP networks (Figure 3). In a real application environment, logic
dictates using one common FCoE connection between the server and network. FCoE will use the same
common driver stacks, cabling, and management applications being used today.
4