Analysis of IPSEC services and their integration in an IP virtual private network

Many approaches may lead to integrate security functions in the intranet/internet services. These functions may be placed at the application layer or at lower OSI layers. IPSEC suite protocols were specified by IETF in order to integrate security functionality at network layer. This paper describes the features of IPSec protocols and identifies the aspects which are not standardized. The network translation address (NAT) functionality used by routers and fire-walls is not always compatible with IPSec. We describe and discuss some solutions for the compatibility of IPSec and NAT. The last part of this paper describes a typical architecture for IP VPN based on IPSec technology.