Converging SAN and LAN Infrastructure with Fibre Channel over Ethernet for Efficient, Cost-Effective Date Centers

Converging SAN and LAN Infrastructure with Fibre Channel over Ethernet for Efcient, Cost-Effective Data Centers Page 3
Unied Networking with Fibre Channel
over Ethernet
It is now possible to carry both LAN and SAN trafc over a
single Ethernet network. FCoE extends Fibre Channel trafc
onto a lossless 10 Gigabit Ethernet fabric, converging LAN and
SAN I/O onto one set of cables. By means of an FCoE-capable
switch, this technology connects transparently to existing Fibre
Channel networks, coexisting with the rest of the topology.
That coexistence enables organizations to implement FCoE
incrementally, reducing effort and risk.
Transmission of Fibre Channel trafc over Ethernet fabric
requires the encapsulation of native Fibre Channel frames into
Ethernet packets, as shown in Figure 3. This methodology
preserves the native format, so FCoE trafc appears as Fibre
Channel trafc to the Fibre Channel fabric. This characteristic
allows IT organizations to maintain the existing environment’s
latency, security, and trafc-management attributes before and
after migration. It also preserves investments in Fibre Channel
expertise and equipment.
For more information about how this encapsulation is structured
and how the data is transmitted using FCoE, see “Fibre Channel
over Ethernet in the Data Center: An Introduction” at http://www.
cisco.com/en/US/solutions/collateral/ns340/ns517/ns224/
ns783/white_paper_FCIAFCoE.pdf. FCoE is a standards-
based technology for storage networking; ANSI T11 FC-BB-5 was
adopted in June 2007, and ratication is expected in 2008, with
strong support from the storage industry as a whole.
The main features of FCoE and a unied fabric are summarized here.
Simplied Infrastructure
A unied data center fabric that incorporates FCoE reduces
overall infrastructure requirements by enabling new servers to
access the SAN without connecting to the Fibre Channel network.
The unied fabric therefore enables IT to install and maintain
fewer network adapters, switch ports, and cables.
Table 1 summarizes these advantages for a hypothetical network
of 16 servers that uses redundant network interfaces for SAN
and LAN connectivity in comparison to a network that implements
FCoE end to end.
In addition to decreased requirements for the cables themselves,
the simpler topology helps reduce cabling errors and make day-
to-day tasks in the server room easier, allowing new servers and
racks to be provisioned more quickly. Reducing cable clutter also
helps avoid restriction of front-to-back airow, which can help
improve cooling efciency. Intel estimates that implementing
FCoE can save up to US$2600 per server.
1
Table 1. Requirements for separate SAN and LAN networks compared to unied fabric.
Figure 3. In FCoE, the Fibre Channel payload is encapsulated in Ethernet frames.
Ethernet
Header
FCoE
Header
SOF
CRC
EOF
FCS
FC
Header
Fibre Channel Payload
Requirements for Separate SAN & LAN Requirements for Unied Fabric
10GbE (no FCoE) Fibre Channel Total 10GbE (FCoE) Fibre Channel Total
Network Adapters/
Ports
16/32 16/32 32/64 16/32 0 16/32
Switches 2 2 4 2 0 2
Cables 32 32 64 32 0 32