ABSTRACT
Contents 16.1 Introduction ................................................................................................................... 394 16.2 Overview of CPS Characteristics and QoS-Security Requirements ............................... 396 16.3 QoS-Security Integration Initiatives: Literature Review ................................................ 397 16.4 Interaction between QoS and Security Metrics .............................................................. 399 16.5 A QoS-Security Integration Technique ......................................................................... 402 16.6 Future Directions ........................................................................................................... 404 16.7 Conclusion ..................................................................................................................... 405 Author Biography .................................................................................................................... 406 References ............................................................................................................................... 407
16.1 Introduction At the beginning, the Internet was egalitarian in terms of providing service guarantees. The general meaning of best-effort delivery in the Internet implied a likelihood that a given user’s packets might be dropped due to congestion or overloading. Because all users were supposedly “friendly,” deliberate overloading (which later became infamously known as the denial-of-service [DoS] attack) was not perceived as a viable threat. Also, it was mutually agreed among users that the protocols requiring strict service guarantees were not suitable for Internet applications. These simple assumptions were practical for that era when the bandwidth was indeed limited (readers may refer back to the original Internet [i.e., the Advanced Research Projects Agency NetworkARPANET], which operated up to 56 Kbps!). As a consequence, the original Internet excluded most real-time communications applications such as voice calls, video streaming, and so forth. As the communication bandwidth continued to increase and communication delays were dramatically reduced due to the invention and wide adoption of faster and reliable transmission media, the Internet could accommodate real-time services (e.g., half-and full-duplex audio and video services) with strict delay and jitter requirements. However, accommodation of such real-time services was done through resource reservation to satisfy the delivery goals.
