A while ago I wrote a few articles describing the various tunnel protocols
used for network virtualization between vSwitches on servers, and between
vSwitches and physical network gateways. These are the mechanisms that
construct overlay networks on top of a physical network. VMWare uses STT as
the tunneling mechanism between vSwitches on servers and VXLAN to communicate
with gateways to the non virtualized world. NVGRE is used mostly by
Microsoft, and is an extension to GRE tunneling that has been around for a
Each one of these mechanisms have their pros and cons. They are all pretty
much standard, or at least published by a standards organization, and
multiple implementations exist of most of them. Outside of my complaint about
the stream like nature of STT, the biggest problem with all of them is the
fact that they are fixed in their definition. The head... (more)
For folks accustomed to the original blogs we post daily, our industry is in
the throes of VMworld bliss, so we will be running the Best of Plexxi this
week. Of course, if you haven’t read this one yet, it’s new for you! Stop
by Booth 747 if you are in San Francisco this week, and say hello!
Over the past few years, Equal Cost Multi Path (ECMP) has seen a very
significant increase in popularity. More importantly, the movement to spine
and leaf based designs in the data center relies heavily on ECMP
functionality for increased bandwidth. @mbushong earlier discussed the
problem of... (more)
Last week Greg Ferro (@etherealmind) wrote this article about his experience
with scripting as a method for network automation, with the ultimate
conclusion that scripting does not scale.
Early in my career I managed a small network that grew to be a IP over X.25
hub of Europe for a few years providing many countries with their first
Internet connectivity. Scripts were everywhere, small ones to grab stats and
create pretty graphs, others that continuously checked the status of links
and would send emails when things went wrong.
While it is hard to argue with Greg’s complaints per... (more)
Much has been published about the Open Compute Project. Initiated by
Facebook, it has become an industry effort focused on standardization of many
parts and components in the datacenter. Initially focused on racks, power and
server design, it has also added storage and now networking to its fold. Its
goal is fairly straightforward: “how can we design the most efficient
compute infrastructure possible”, a direct quote from its web site.
The focus of OCP has been mostly around hardware designs and specifications.
If you look at the networking arm of OCP, you find several Top of Rack... (more)
We love analogies. No matter what the topic, analogies are a great way to
explain something in a different context to make a specific point with a
frame of reference that may be more familiar to those we are making a point
to. There is one that seems to come back over and over again in our industry,
the one that compares the network to the power grid, network connections to
power plugs. I had not heard it for a while but at Interop last week, I
heard it used twice in booth demonstrations as part of plug and play pitches.
And I really do not like that analogy.
The comparison to ... (more)