 is to define all computers using a certain network layer protocol to make up their own VLAN. The VLAN of a certain protocol Data Communications can be further divided into smaller VLANs by defining a certain set of the network layer addresses that make up a VLAN. 6.6 The Internet The Internet has developed into the major information network in the world and this development will continue. We review here its development and the most important protocols on which its operation is based. 6.6.1 Development of the Internet The worldwide Internet network developed from experimental computer networks in the 1960s to a worldwide university network in the 1970s and 1980s. The Department of Defense of the United States supported the origi- nal technical development. The aim was to design a fault-tolerant data net- work that would stay operational in crisis situations. Internet technology is not as formally standardized as other public tele- communications networks. There is no globally authorized standardization body such as ITU-T where all nations together participate in the develop- ment of the network. However, some centralized control is required and there is an organization that manages the development of the Internet. The main institution in the Internet Society (ISOC) responsible for technical development is the Internet Engineering Task Force (IETF) in the United States. IETF updates Internet standards. Internet addresses, network num- bers, are assigned by the Network Information Center (NIC) to avoid conflicts. Technical specifications of the Internet are called Requests for Comments (RFCs) instead of standards. This gives the reader an idea about how official they are. This freedom in development of the Internet has speeded the growth of the network. Some RFC documents are approved and published as Internet standards, STD documents, by the Internet Activities Board (IAB). All organizations mentioned here belong to ISOC, which is a nonprofit international organization for global cooperation and coordination of In