Chapter 10 - Quality of service and security

Abstract

This chapter addresses issues that cross layer boundaries and appear in several or all layers of the protocol stack. The layered architecture of the protocol stack is designed to hide the complexities of one layer from others. As a result, the network is agnostic to the specifics of any application using the network. From the perspective of transport and network layers, applications set up connections or send packets and there is no difference between different types of applications. In practice, however, there are applications that have specific requirements for the performance of the network. To accommodate such applications, the network can be extended to provide “quality of service” (QoS). Security is an important aspect of any information system. In networks, security protocols are used to ensure confidentiality, authenticity, and integrity of data transfers. Most protocols use block-based ciphers with symmetric session keys. These session keys are established through cryptographic techniques based on asymmetric keys that do not require preshared keys. Additionally, availability of access to network resources is an important consideration that cannot be addressed by cryptographic protocols. To mitigate the impact of denial-of-service attacks, additional functionality in network systems is necessary.