ly disruptive in the software world, with the Linux operating system being the starkest example. Linux is extremely successful with most web servers in the world running on it and being at the core of the Android operating sys- tem. While Linux and most other open source projects in the past initially were driven by volunteers running code in their spare time, in the past few years the vast majority of open source codes are in fact contributed by corporations. The Tux penguin, the Linux mascot, has become well known and widely recognizable (see Figure 2.14). Linux is also extensively being used by enterprises, however this does not necessarily mean that companies using Linux simply download the software (which is often, albeit not always, available free of charge), but rather most choose to rely on integrators (such as RedHat), which provide solutions based on open source, along with support and other services important for enterprises. With open source being successful in enterprise and data centers, it inevitably drew atten- tion from telecom operators, which at first started from the CN. At the time of writing this book, there are a number of open source LTE EPC implementations available; for example, 2 Market Drivers Figure 2.14 Tux the penguin, mascot of Linux open source operating system. Magma, which was developed by Facebook and distributed under the Berkeley Software Distribution (BSD) license. Besides the EPC, there are several open source activities targeting orchestration, which is an important component required to run the network in a virtualized environment. The two best-known examples are: ONAP was formed as a combination of the Linux Foundation's OPEN-Orchestrator Project (OPEN-O), and the AT&T ECOMP (Enhanced Control, Orchestration, Manage- ment and Policy). It is an open source software for design, creation, and orchestration of primarily CN services. OSM is an ETSI initiative for the development of open source NFV Management and Orchestration software, meant to achieve similar goals to those o