ity, merging multiple services together is going to be difficult. Careful design of ordering and parallelism is critical to the performance and the correctness of the entire service chain. 6.3 Summary In this chapter, we review existing open source activities that are related to SDN, NFV, and can be used in building 5G's new require- ments. These projects have wide participants from NEP, CSP, and customers. They are the key enabler for the whole industry and ecosystem. References 1 AT&T, "AT&T SXSWPress Release," 2 "Global Mobile Network Traffic-A Summary of Recent Trends," GSMA Documents, 2011, [Online]. http:// www.gsma.com/spectrum/wp-content/uploads/2012/03/ analysysmasonpaperonglobalmobilenetworktrafficcorectedjuly11 .pdf (Accessed November 2016). "Ericsson Mobility Report," November 2012, [Online]. http:// www.ericsson.com/res/docs/2012/ericsson-mobility-report- november-2012.pdf (Accessed November 2016). 4 "Ericsson Mobility Report," June 2014, [Online]. http://www pricsson.com/res/docs/2014/ericsson-mobility-report-june-2014 .pdf (Accessed November 2016). 5 "The Zettabyte Era-Trends and Analysis," " June 2014. [Online]. http://www.cisco.com/c/en/us/solutions/collateral/ serviceprovider/visual-networking-index-vni/VNI_ Hyperconnectivity_WP.html (Accessed November 2016). 6 "Cisco Visual Networking Index: Forecast and Methodology, 2013-2018," June 2014. [Online]. http://www.cisco.com/c/ en/us/solutions/collateral/service-provider/ip-ngn-ip-next- generationnetwork/white_paper_c11-481360.pdf( (Accessed November 2016). 7 R. Sherwood, G. Gibb, K.-K. Yap, G. Appenzeller, M. Casado, N. McKeown, and G. Parulkar, "Can the production network be the testbed?," in Proceedings of the 9th USENIX Conference on Operating Systems Design and Implementation, OSDI'10, 2010. 8 N. McKeown, T. Anderson, H. Balakrishnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker, and J. Turner, "OpenFlow: enabling innovation in campus networks," ACM SIGCOMM Network Function Virtualization: Concepts and Applicability in 5G Networks, First Ed