ssues. Therefore the point is to use commercial grade rather than test equipment. This test is similar to "Safe For Network" testing required by some operators to ensure that a new device does not cause any harm to the shared network. Plug fest The scope of the plug fest is to ensure interoperability between equipment from different vendors, including all components that make up the O-RAN system (Fig. 10-6). Chapter 10 Interoperability and test 339 SA Test Configuration NSA Test Configuration FIGURE 10-6 Scope of plug fest. O-RAN is hosting plug fests for two main reasons. The first is to showcase development progress and give O-RAN member a platform to display engineering progress to date, specifi- cally when targeting combined efforts from multiple companies. The second is closer to what the name indicates: to have an environment for interoperability testing for member companies. This validates published O-RAN standards (such as the fronthaul standard between DU and RU) and sets development milestones. Plug fests are hosted in America, Europe, and Asia. The first plug fest took place in December 2019 with 35 member companies attending, with the second in the summer of 2020 and 55 companies comping together. Attendance is growing from here. As example of what is achieved during these plug fests, we quote a few of them from the press release associated with the Indian 2020 Plug Fest as hosted by Bharti Airtel ²: Altiostar and NEC showed interoperability between O-DU and O-RU including support for the C-, U-, S-, and M-plane protocols. VVDN, Xilinx, and Viavi demonstrated O-DU fronthaul using the Xilinx T1 telco accelerator card against Viavi test equipment. Testing included C-, U-, and S-plane protocols. Mavenir demonstrated coverage/capacity optimization and mobility robustness optimization, proving 01-interface compliance. STL and ASOCS demonstrated mobile load balancing and through that E2 interfacing. 340 Open Radio Access Network (O-RAN) Systems Architecture and Design Altran successfully demonstrated ENDC X