Rethinking the Network

Marten Terpstra

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Top Stories by Marten Terpstra

There have been many articles describing overlay networks in the past few quarters. It's a relatively straightforward concept, not far removed from some of the older VPN technologies very popular a while ago. The actual transport of packets is probably the simplest, it is the control plane that is much harder to construct and therefore explain. It is therefore also that the control plane in overlay networks has seen the most innovation and change, and is likely to change some more in standard and proprietary ways in the next little while. A perfect example is the use of IP Multicast for unknown, multicast and broadcast traffic as defined in the latest IETF draft for VXLAN, but controller implementations try and avoid IP Multicast as part of the necessary data path. Which will continue to lead to changes in the control plane for learning, distribution of destinations... (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)

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)

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)

The Silence of The Lambdas

We still see quite a few eyebrows raised when we explain how we use WDM optics in our datacenter solution. In the various descriptions of the Plexxi solution it is often mentioned and referred to, but it is worth explaining what that optical infrastructure actually looks like and why it is part of our solution. One of the key attributes of the Plexxi solution is the ability to create network topologies at L1, L2 and L3 that meet the need of the workload offered, calculated based on the load on the network, and the Affinities created that describe the needs of specific applicatio... (more)