When the new FCoE (Fibre Channel over Ethernet) VN2VN
(aka Direct End Node to End Node) was defined in the T11.3 FC-BB-6 Ad Hoc
Working Group it was assumed that it would find a niche in the Low to medium IT
organizations that wanted to have compatibility with Fibre Channel (FC). Though
that is still valid, it looks as though it may also be important to some of the
new "Cloud" services that provide Infrastructure as a Service (IaaS).
FCoE VN2VN is a additional FCoE protocol which permits FCoE
End Nodes such as Servers acting as "Initiators" and FCoE End Nodes
such as Storage Controllers acting as" Targets" to either directly
attach to each other or attach with only lossless Ethernet switches between
them (perhaps as few as one switch between the End Nodes). This form of FCoE does not require any FC/FCoE
networking equipment.
FCoE VN2VN permits the IaaS organization to enable their
installation to provide storage interconnectivity with FC and/or FCoE. FCoE VN2VN capability can be used
to give a customer an FCoE VN2VN connection between the servers and the
storage that are supplied by the IaaS provider. This VN2VN interconnect can
provide the fastest end-to-end connection with the fewest number of
"hops" as possible. That is, the
data path can traverse between the server and the storage unit by passing
through perhaps as few as one Lossless Ethernet switch. No FCF (Fibre Channel
Forwarder) is required, which means that no additional FC switching processes
and overhead are involved in the data path.
In addition, the lossless Ethernet switch can be provided by a great
number of vendors, thus permitting the lowest possible cost data path. This means that the IaaS provider can give a
customer the fastest interconnect at the lowest possible cost.
To enable this type of capability there is certain
implications upon the configuration of the "Cloud" installation. For
example: if the customer would like to purchase infrastructure where the
required servers and storage can fit into a single rack (or even a 2-3 rack
side-to-side configuration) they are candidates for FCoE VN2VN
interconnection. In such a configuration
a lossless Ethernet switch can be placed at the top of the Rack (or Rack set)
and Ethernet connections run from the servers to the Switch and then to the
storage units. For total installation flexibility the Top-of Rack (ToR)
switches may also be physically interconnected to an End-of-Row (EoR) Director
class FCoE switch that may have full FCF capabilities. However, the EoR Director would have no
direct involvement with the data path for this IaaS rack-set. It is also possible to have a ToR switch at
the top of each rack and have them interconnected with each other. In this
case, the data path may go through two ToR switches but would still not need to
go through the EoR FCoE Director.
So depending on the needs of the customer, and the physical
configuration required by the provider, it is possible to obtain the minimum
switch/"hop" count and lowest latency interconnect. This means that
the provider of IaaS services can "carve-out" a rack or set of racks
that can be dedicated to a specific IaaS customer, and give them isolated
service yet when that customers grows and has a much larger requirement, or
they leave the IaaS provider's installation, the installation can easily
re-task the servers and storage, or expand to other racks of server and
storage, without needing to physically re-cable the network configuration.
In this example, the IaaS systems and storage are given
their own VLANs that can be used by the FCoE VN2VN to permit
"direct" connection between the IaaS customer's servers and storage
without involvement of other systems within the IaaS providing installation. It
should be noted that when the customer either leaves the installation or
expands, the provider can re-task the equipment and remove the VLAN
specification, and in the case of expansion utilize a regular FCoE interconnect
(via the EoR director FCoE switches).
Likewise, a company often has the need to provide IaaS like
services to various internal departments which for various company technical or
"political" reasons need to be provided with dedicated server and
storage rack(s) which can function as isolated environments for various company
departments and projects. This then becomes an internal IaaS "Cloud"
environment in which FCoE VN2VN can often be an appropriate solution to
this configuration requirement.
But independent of the internal or external
"Cloud" IaaS environments FCoE VN2VN is still appropriate for
the smaller computing environments such as "Big Box" stores, "Disaster
Recovery Trailers" and small to medium IT installations.
In smaller organizations such as local "Big Box"
stores, they can have their whole data center located in a single rack which
has the appropriate servers and storage all inclusive. In this type of configuration the various
Server vendors can be asked to bid on the "total rack" that includes
FCoE VN2VN,
and often obtain a "total solution" at a minimum cost. I was once associated with an organization
that wanted to sell such configurations to the big box stores but was deterred
because of the cost of the Fibre Channel Connections and switches. That concern
is no longer relevant when FCoE and VN2VN connections, within the rack, are
utilized.
I also understand that various "disaster recovery trailers"
can utilize such configurations in their trailers when they are used to provide
temporary IT service to big box stores (and others) after various disasters.
And, of course, when it comes small to medium IT
installations (ones that fit within a single or few Racks) FCoE VN2VN
configurations seems to offer a high performing low cost storage interconnect
solution that is compatible with future growth into a full FCoE or FC
installation. These types of
installations may also be seen as a valuable asset that can easily be
integrated during a merge or buy-out with larger organizations that probably
have an FC and/or FCoE.
