Is your network ready for VDI, or is it time to mesh?
It's been a little more than
20 years since I designed my first from-scratch cable plant, but one basic fact
hasn't changed, no matter how much the physical media and the wire protocols
have evolved. That eternal truth is really quite simple: The boss and the users
don't care about the network until it ceases to work. Then they care a lot.
The good news is that the
physical and link layers are much easier to deal with than they were in my Wild
West days. There's no more weighing the pros and cons of Token Ring compared
with Ethernet, no more coaxial cables running from one workstation to the next,
no more IBM Type 1 shielded twisted-pair cables to wrestle with, and available
bandwidth to the desktop is 100 times what we had to work with in those days.
But the bad news is that we may need to rethink the way we connect desktops to
the network if VDI (virtual desktop infrastructure) ceases to be a novelty and
becomes part of the norm.
That's because, as a rule,
desktops connect through a single port on a single access switch. Switches are
reliable enough that such a connection strategy works, and modern cabling
plants can withstand most physical stresses. But latency can prove to be a
silent killer, making the best-planned VDI deployment into a nightmare, no matter
what the underlying cause.
The best way to avoid
latency surprises is to know what the network is already tasked with before one
adds more traffic to the network. Logs and traffic analysis are useful ways to
acquire that knowledge, but there's really no substitute in my book for
spending some time in front of the blinking lights.
"Follow the flashing LEDs"
will only get you so far, of course, if your patch panels look like an octopus
wrestling a bowl of spaghetti. I can't stand a messy panel on the best of days,
but when I'm trying to figure out a network problem in a wiring closet where
cables are tangled, unlabeled and routed without any thought to how someone
might troubleshoot, my mood oscillates between "Jesus wept" and the version of
Ezekiel 25:17 featured in the movie Pulp
There's only so much one can
do to beef up the network at the point of the access switch; running multiple
cables to the desktop is cost-prohibitive in many environments, so there's
always going to be a single point of failure at that level. What can be
accomplished more easily and economically is to mesh access switch connections
to the distribution layer, providing each switch's connected devices with
multiple paths to the core network and associated resources.
Load balancing and link
trunking are old hat when connecting core networks and distribution networks,
but it's time to push these technologies out to the connections between access
networks and distribution networks. When used in a meshed environment, these
can provide against almost any contingency that doesn't involve a backhoe
punching into a building's data connections.
Although techniques such as
Teradici's PCoIP (PC over IP) exist to wring efficiency out of network
connections at a higher level than basic network connectivity, these won't help
in an environment that's poorly designed or where the network is frequently
In obsessing over the last
few hundred feet, I'm focusing on a small piece of the much larger puzzle of
making VDI technology work for business. However, it's a piece that's very easy
to overlook, and one that's not terribly difficult to fix in the early stages
of a project.