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Rethinking the Network

Marten Terpstra

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Top Stories by Marten Terpstra

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 while. 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)

[Plexxi Rewind] ECMP: It’s not all equal, or even normal

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)

Scripting Is Automation, But Automation Is Not Scripting

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)

Open Compute, Open Switch API and Open Network Install Environment

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)

Different Shades of Invisible

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)