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Rethinking the Network

Marten Terpstra

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Latest Blogs from Marten Terpstra
Many years ago Gartner introduced their technology Hype Cycle, which maps visibility against maturity for new technology. The Hype Cycle in essence states that many new technologies get a large amount of visibility early in their maturity cycle. The visibility and enthusiasm drops sign...
Through http://blog.ipspace.net I landed on this article on acm.org discussing the complexity of distributed systems. Through some good examples, George Neville-Neil makes it clear that creating and scaling distributed systems is very complex and “any one that tells you it is easy is e...
Whenever we get to the end of a year we have this tendency to reflect on what has happened in the past year and how we can improve in the coming year. It’s natural to use the change of calendar year as a point in time to think back, even though practically speaking it is usually the mo...
In the world of Anything-as-a-Service (I will leave the acronym to your imagination), Network-as-a-Service is not a new term. In fact, it even has its own wikipedia page which will tell you it has been used for many years now, well before the current set of service related terms in IT ...
You have probably realized we are having a Big Data kind of week here at the Plexxi blog. And for good reason. The amount of development and change in this big bucket of applications we conveniently label “Big Data”, is astonishing. Walking around at Hadoopworld in New York last week, ...
I am sure our work environment is not all that different from many others. There are large whiteboards everywhere and you cannot find a meeting room that does not have circles, lines and squares drawn on them. Some of our favorite bloggers have written blogs about network drawing tools...
Throughout the development cycle of new features and functions for any network platform (or probably most other products not targeted at the mass market consumer) this one question will always come up: should we protect the user of our product from doing this? And “this” is always some...
Triggered by a discussion with a customer yesterday, it occurred to me (again?) that network engineers are creatures of habit and control. We have strong beliefs of how networks should be architected, designed and build. We have done so for long times and understand it well. We have tw...
In the past few weeks at Plexxi we spend probably an unreasonable amount of time talking about, discussing and even arguing over ethernet cables and connectors. As mundane as it may sound, the options, variations, restrictions and cost variations of something that is usually an afterth...
In a blog week dedicated to the application and the policies that govern them, I wanted to add some detail on a discussion I have with customers quite often. It should be clear that we at Plexxi believe in application policy driven network behaviors. Our Affinities allow you to specify...
This week we hosted a (potential) customer that really wanted to dig in and understand what we do and how we do it.  Not the powerpoint kind where we go through endless monologues of all the good stuff we say we do, but roll up the sleeves, let’s install some boxes and actually see wha...
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 we...
Over the past few weeks I have had several conversations related to calculating network topologies and how packet forwarding is done based on those topologies. I wrote this post about a year ago explaining some of these details, but after a conversation with a customer earlier this wee...
In Monday’s blog post, Derick explained the network engineering cycle, traversal in the referential space and the need to provide solutions that enable the network engineer to do his or her job better, more accurate, easier, simpler, more complete. We cannot automate or encapsulate a n...
This week I read a perfectly reasonable article by Tom Hollingsworth, which then deteriorated in the comments section to a “you don’t know how a switch works” exchange. Both participating parties miss the boat on several of their comments, but the far more interesting question is why w...
In the past few weeks you may have seen several press releases and articles talking about 25 Gbit Ethernet. Just when you got used to ethernet speeds being a nice decimal based system where we simply add zeros every few years, someone threw in 40GbE a few years ago. And that’s ok, powe...
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 t...
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...
As an SDN network provider focused on the datacenter, we spend a good amount of time understanding the state of data centers today, tomorrow and some time into the future. There is no question that the use of Software as a Service (SaaS) applications in the cloud is growing rapidly....
Some people believe good or bad things always happen in threes. I believe you will always be able to find three (and probably more) things that are good or bad and somewhat related, but sometimes I get surprised by the apparent coincidental appearance of several closely related “things...
About 8 years ago at my previous employer we started a project related to Autonomic Networking. Autonomic Networking is modeled after Autonomic Computing, an IBM initiative from the early 2000s, targeted at creating self managing computing elements. The network version intends to creat...
A book I have had on my fairly small pile of books to keep is “The Five Dysfunctions of a Team” by Patrick Lencioni. In this book he outlines 5 critical failures of teams, key areas for any leader to address. Patrick walks through these with a fictional story to outline how each of the...
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 us...
This week, Ivan Pepelnjak wrote an article describing queueing in today’s ethernet switches. He walks through FIFO queueing, on to Class Based Queueing to Virtual Output Queueing in line card based switches. It is a very nicely written article explaining the basics of queueing mechanis...
The days of completely separate storage network technologies are quickly fading. It feels like it’s only a few years ago that Fiber Channel was the way to create large scale storage networks. Big honking storage devices on a separate network, connected to Fiber Channel switches, connec...
IP Multicast is one of those technologies that most everyone loves to hate. It’s almost the perfect example of how complicated we have made networking. Getting IP Multicast to run depends on several protocols that are all somewhat intertwined or dependent on each, their relationship so...
In my 20+ years of doing this networking thing, I have been part of many a network debugging party. Often in the capacity of the vendor that “caused” the problem, but also at times as part of a team  attempting to create a network that was probably slightly overbuilt for its purpose (r...
In reviewing some opportunities for Plexxi this week, I was reminded that we have made things very hard on ourselves. Through no one’s fault but our own we have created monsters of networks that are impossible to maintain, debug, diagnose and understand. I have been lucky in my career...
Earlier this week I had some interesting conversations with @davehusak. Where the conversation started early in the day with a discussion on overlay networks and what network functions are performed where and in what context, later in the afternoon the discussion moved to networking so...
Earlier this week, Ethan Banks wrote a very nice article about Mellanox’s dual spine and leaf network in support of a large amount 10GbE access ports. After describing the scaled up network design, he reviews 8 observations about the design, not to point out good or bad, but merely to ...
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...
Perhaps not as popular as its brothers and sisters I, P and S, Network-As-A-Service or NaaS has slowly started to appear in industry press, articles and presentations. While sometimes associated with a hypervisor based overlay solution, its definition is not very clear, which is not at...
I find it interesting to see how we as a (sub) industry get into cycles of things that we think matter, or want to talk about. We are all influenced by each other and blog posts trigger new blog posts and a lively discussion ensues. What is interesting is that sometimes these come in f...
A few weeks ago I attempted to explain what Plexxi does to someone that was not very familiar with computer networking and data centers. He owns a landscaping business and his knowledge of computers is mostly limited to casual use for browsing and some basic billing and quoting. Those ...
While doing some competitive analysis, I read this paper that was presented at the 21st Symposium on High Performance Interconnects. The paper discusses the data path performance of spine and leaf networks and was written by Insieme Networks’ Mohammad Alizadeh and CTO Tom Edsall. Moham...
What started out as a mechanism to program flows into network switches and routers in a standard way is evolving into a full blown forwarding engine programming and management specification. In the latest version of the spec (1.4, released in October 2013), the abilities exist to confi...
It is human nature to try and relate new information and new ways of doing things to something that we know, something we are familiar with. Often when we talk about the way we fit traffic onto a Plexxi mesh network, the reaction is “I know what you mean, you are doing traffic engineer...
Not entirely unexpected, the optical capabilities in our switch have provoked questions from customers and potential customers on whether the Plexxi solution could be used to create campus, metro or even long distance multi site fabrics. The answer to that question is a resounding yes,...
We get quite caught up in high level architectures at times. It is good to read some posts that focus on design and implementation and the practicality of taking higher level architectures to reality. Two of Ivan’s posts caught my eye this week. In the first, he discusses the differenc...
Last week I walked through the packet formats for VXLAN and NVGRE specifically focused on ways by which the overlay packets provide information to the physical network that help the physical network. Some of the initial extreme thoughts that the overlay and physical network can and sho...