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Rethinking the Network

Marten Terpstra

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Top Stories by Marten Terpstra

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 se, I believe the key point is missing. And it has nothing to do with scripting. In a reply, Ivan’s last comment touches on the real issue. We have been scripting our networks against CLIs forever and I will bet you most folks will consider it successful, even though it may be a pain. The ... (more)

Attention: Overlay Tunnel Construction Ahead

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 ... (more)

Network Services, Abstracted and Consumable

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 all surprising. Our industry does not do too well in defining new terms. I ran across this presentation from Usenix 2012 that details a NaaS solution that adds a software forwarding engine to switches and routers that provide specific services for some well known cloud computing workloads. I have ... (more)

Complexity Kills Networks

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. Most of it has been in an R&D organization for a large network vendor, but always in positions where I was close to customers, close to customer networks, and of course with that comes the “close to customer networks that are not working well”. And while there are always exceptions, in most of the... (more)

What SDN Can Do for Multicast Topologies

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 sometimes explicit, sometimes implicit. Even trying to describe the basic operation is complicated. When an application or service provides information using IP multicast, it simply starts sending it onto a specific multicast group. The multicast router for the subnet of the sender sees the incoming m... (more)