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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)

Network Design in a Virtual World

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 difference in how application and network folks look at the deployment of tiered applications and what that means for the security between them. In the second, he asks a question that our entire industry has under delivered on for more than a decade: why can’t we have plug-n-play networking? They may appear ... (more)

Converging Your Storage Network Without Fear

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, connected with Fiber Channel adapters into servers. With 10GbE becoming cost effective and matching or outperforming 2, 4 or even 8Gbit Fiber Channel, Fiber Channel over Ethernet was invented, mostly as a mechanism to allow Ethernet based attachments to existing Fiber Channel installations. It’s a bit clu... (more)

Traffic Advisory: Your Packets May Be Delayed

The past few years have seen a dramatic improvement in the latency in network switches. Single ASIC based switches can all pretty much switch packets in less than a microsecond. Current 10GE switching silicon provides anywhere from 300 to 800 nanoseconds, specialized silicon shaves that to less than 200 nanoseconds when limiting the amount of searching that needs to be done by reducing the size of lookup tables. Even other solutions play some smart tricks by providing forwarding hints for intermediate switches make those lookups take less than 50 nanoseconds. Modular switches i... (more)

Many Waze to Cambridge

I work mostly in Plexxi’s office in Nashua, NH. That is about a 12-minute commute for me, backroads only through two sleepy towns. Very convenient and a great improvement over my previous commute. Every now and again I make the trek out to our Cambridge office and it is painful. About 40 miles and around 45 minutes of mostly highway on a good day; early morning this is easily a 90-minute exercise, and finding myself on the road for two hours is not unusual. I am not very attached to a GPS, but whenever I travel a distance or know I am going to hit traffic, I turn on Waze on my p... (more)