Converged networks with Fibre Channel over Ethernet and Data Center Bridging

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HP Virtual Connect FlexFabric with FCoE
Now that we have achieved an acceptable level of LAN convergence with Flex-10 technology, the next
logical step is to add LAN/SAN convergence technology. Virtual Connect FlexFabric broadens Virtual
Connect Flex-10 technology to provide solutions for converging different network protocols. We plan to
deliver the FlexFabric vision by converging technology, management tools, and partner product portfolios
into a virtualized fabric for the data center.
Emerging standards for network convergence
Converged networks require new standards. The International Committee for Information Technology
Standards (INCITS) T11 technical committee creates the standards that relate to storage and storage
networking based technologies. The IEEE 802.1 Work Group is responsible for developing two types of
standards:
• Standards common to all IEEE 802 defined network types (for example, Ethernet and Token-Ring)
• Standards necessary to support communication within and between these network types.
FCoE standard
FCoE is an emerging technology under development by the INCITS T11 technical committee. INCITS/ANSI
T11.3 FC-BB-5 is the official standard. It includes two protocol definitions: FCoE and FCoE Initialization
Protocol (FIP). The FCoE protocol defines the encapsulation of FC frames into Ethernet frames. FIP defines a
fabric discovery protocol, creates an Ethernet version of FC fabric login services, and defines the protocols
for handling MAC address assignment and association with World Wide Names (WWNs). FCoE relies on
improved flow control, well-defined traffic shaping, and multiple TC support that IEEE 802.1 DCB standards
provide.
FCoE protocol encapsulation
FCoE is different from previous attempts to move SCSI traffic over Ethernet. The FCoE protocol allows
efficient, high performance conversion between FCoE links and FC links in layer 2 switches. DCB
enhancements offer lossless operation for some TCs. This lets us place the FC protocol directly on top of
layer 2 (link layer) Ethernet, so we don’t have to rely on more complex transport protocols such as TCP to
ensure lossless behavior. Implementing FCoE in this way lets us develop devices such as adapters and
switches that use most of the existing FC logic on top of the new DCB/Ethernet physical interfaces.
The FCoE protocol encapsulation standard requires IEEE 802.1Q tags. Each FCoE frame contains explicit
TC/priority tags for efficient processing in layer 2 DCB-capable Ethernet switches. Data centers deploy
FCoE for intra-data center use with a similar span as a switched LAN subnet or SAN fabric because FCoE is
a layer 2 protocol and does not use the layer 3 IP protocol.
FCoE encapsulates FC frames, including FC frame delimiters, headers, payload, and frame check
sequence, within the Ethernet frames using a format illustrated in Figure 3.