The biggest Internet layer security protocol family is IPsec, which is a fairly complex umbrella IETF standard, developed since 1995. IPsec is an open, vendor-independent architecture and a kind of VPN standard. It can also be used for leased lines and frame relay traffic. The main aim of IPsec, however, is to provide privacy, integrity Overall QoS Content security Appl-logic support Content support/ QoS adaptation at Security, service enablers service level Service QoS adaptations at (RTP etc.) encryption layer service level (RTP...) Service Network control manage- Charging clients, IPsec servers Signalling Mobility management Network DNSsec Numbering Dimensioning Switching and routing Availability Synchronization (control and Service connectivity Connectivity resources) resources Network Transmission management Frequency (incl echo Canc Organization Figure 6.29 Position of some security enablers Understanding Changing Telecommunications - Building a Successful Telecom Business and authenticity to information transferred across IP networks. IPsec addresses all of the threats to Internet (such as loss of privacy and data integrity, identity spoofing and denial of service) in the network infrastructure itself. IPsec provides IP network layer encryption. Normally tunnelling is used, but there is an alternative, called transport mode. The customers to IPsec are all IP-based protocols, such as TCP, UDP and ICMP. For staff working with security a layered view and an 'FP view' are useful, for example when positioning the security enablers. See Figure 6.29. Quality of Service 'Quality of service is not what it used to be.' 7.1 OBJECTIVE The overall objective of this chapter is to support the elaboration of a Quality of Service plan and the implementation of a service plan as far as Quality of Service is concerned. 7.2 INTRODUCTION 7.2.1 WHAT IS QUALITY OF SERVICE? Quality of Service (QoS) is the collective measure of the level of service to a subscriber (ITU-T E.800). The service in question used to be voice, but now ma