TABLE OF CONTENTS This appendix briefly reviews some key technologies referred to in this book, including Internet, XML, PKI, IN, OSA-Parlay, mobile networks, and CAMEL. It only serves as a quick reference; for a more comprehensive treatment of these technologies, please refer to the author's companion book, Next Generation Intelligent Networks (Artech House, 2002).
The Internet is best characterized as the worldwide interconnection of data networks, using the IP. The IP sends data in the form of discrete packets or datagrams, as they are sometimes called in IP terminology. IP packets consist of two parts: a header that contains information about the origin and destination of the packet, and the content of the packet to be filled by the application.
Packets are sent from origin to destination by routers, much as letters are sent through the mail. When a router receives a packet, it looks at its header to determine the destination and consults a routing table to decide where to route the packet next. The next destination for the packet may be the destination computer, or it may be the next router on the path to the destination.
Apart from IP there are many other protocols that make the Internet work. The IETF structures these protocols in four layers, as shown in Figure A.1:
The network interface layer represents the underlying physical network. This can be any kind of network as long as is it can transport data from one point to another, for example,...
