Information Technology Reference
In-Depth Information
Figure 6.8
h e most common
Fibre Channel
confi guration: a
switched Fibre
Channel (FC-SW)
SAN. h is enables
the Fibre Channel
LUN to be easily
presented to all the
hosts while creating
a redundant net-
work design.
VMFs
datastore
VMFs
datastore
VMFs
datastore
ESXi host
ESXi host
ESXi host
Each ESXi host
has a minimum of
two HBA ports,
and each is
physically
connected to two
FC switches.
FC switch
FC switch
Each switch has a
minimum of two
connections to two
redundant front-end
array ports (across
storage processors).
FC array
FC
LUN
Switched Fibre
Channel
How Different Is FCoE?
Aside from discussions of the physical media and topologies, the concepts for FCoE are almost
identical to those of Fibre Channel. h is is because FCoE was designed to be seamlessly interoper-
able with existing Fibre Channel-based SANs.
All the objects (initiators, targets, and LUNs) on a Fibre Channel SAN are identii ed by a
unique 64-bit identii er called a
worldwide
name
(
WWN
). WWNs can be worldwide port names
(a port on a switch) or node names (a port on an endpoint). For anyone unfamiliar with Fibre
Channel, this concept is simple. It's the same technique as Media Access Control (MAC)
addresses on Ethernet. Figure 6.8 shows an ESXi host with FCoE CNAs, where the highlighted
CNA has the following worldwide node name: worldwide port name (WWnN: WWpN) in the
identii er column:
20:00:00:25:b5:10:00:2c 20:00:00:25:b5:a0:01:2f
Like Ethernet MAC addresses, WWNs have a structure. The most signii cant two bytes are
used by the vendor (the four hexadecimal characters starting on the left) and are unique to the
vendor, so there is a pattern for QLogic or Emulex HBAs or array vendors. In the previous exam-
ple, these are Cisco CNAs connected to an EMC VNX storage array.
Fibre Channel and FCoE SANs also have a critical concept of zoning. Fibre Channel switches
implement zoning to restrict which initiators and targets can see each other as if they were on
a common bus. If you have Ethernet networking experience, the idea is somewhat analogous to
non-routable VLANs with Ethernet.
