Show notes
Interview with Bob Lantz and Brian O'Connor of ON.LAB, about Mininet software for simulating networks. Bob previously gave a talk about Mininet (slides, video) at the Open vSwitch 2015 Fall Conference. Bob describes the mission of ON.LAB and how he ended up there. He talks about introducing the idea of a network operating system to ON.LAB. He mentioned that his interest in networks arose from a lecture by Nick McKeown in the EE380 lecture series at Stanford, in which Nick stated: “Networks are like hardware without an operating system,” which piqued Bob's interest. Brian relates his own experience getting involved with SDN, Mininet, and ON.LAB. Bob describes the genesis of Mininet by analogy to mobile device development. Mobile device development is a pain because no one wants to spend all their time with these tiny devices, so you use a simulator. For network development, you need a simulator too because otherwise you need a huge stack of expensive hardware. Mininet was directly inspired by a network namespaces-based simulator developed in-house at Arista for testing EOS. Bob compares Mininet to Docker and other container systems. All of these are container orchestration systems that make use of the “namespace” and control group (cgroup) features of the Linux kernel. Mininet gives more control over the network topology than the others. Bob talks about limitations in OpenStack networking and what he'd like to see OpenStack support in networking. Brian describes a trend in NFV toward minimization, that is, reducing the amount of overhead due to VMs, often by running in containers instead. He speculates that containers might later be considered too heavyweight. In Mininet, isolation is à la carte: the aspects of network isolation, process isolation, and so on can all be configured independently, so that users do not experience overhead that is not needed for a particular application. Bob talks about the scale that Mininet can achieve and that users actually want to simulate in practice and contrasts it against the scale (and particular diameter) of real networks. Versus putting each switch in a VM, Bob says that Mininet allows for up to two orders of magnitude scale improvement. His original vision was to simulate the entire Stanford network of 25,000 nodes on a rack of machines. Bob talks about distributed systems built on Mininet, which are not officially integrated into Mininet. Distributed Mininet clusters are a work in progress. In general, Mininet scales better than most controllers. Bob compares Mininet to ns3. ns3 was originally a cycle-accurate simulator, but this made it hard to connect to real hardware and run in real time, so it has moved in a direction where it works in a mode similar to Mininet. Bob describes the Mininet development community, based on github pull requests. Bob describes a paradox in which they'd like to accept contributions but most of the patches that they receive are not of adequate quality. Bob talks about performance in OVS related to Mininet, as a review of his previous talk, and especially related to how Mininet speaks to OVSDB. The scale of Mininet doesn't interact well with the design of the OVS command-line tool for configuring OVS, which doesn't expect thousands of ports or perform well when they are present. Bob reports that creating Linux veth devices is also slow. Bob describes how to generate traffic with Mininet: however you like! Since you can run any application with Mininet, you can generate traffic with any convenient software. Brian's wish list: improving the support for clustering Mininet and the ability to “dilate time” to make Mininet simulation more accurate to specific hardware, and the ability to model the control network. You can contact Brian via email. Bob recommends emailing the Mininet mailing list to get in contact with him. OVS Orbit is produced by Ben Pfaff. The intro music in this episode is Drive, featuring cdk and DarrylJ, copyright 2013 by Alex. The bumper music is Yeah Ant featuring Wired Ant and Javolenus, copyright 2013 by Speck. The outro music is Space Bazooka featuring Doxen Zsigmond, copyright 2013 by Kirkoid. All content is licensed under a Creative Commons Attribution 3.0 Unported (CC BY 3.0) license.