Networks and Protocols

Internet Service Provider (ISP) is an organization that provides Internet access services and other Internet-related services.

ISP services may include:
• Internet access via dial-up and cable;
• Wireless Internet access;
• Allocation of the disk space for the storage and maintenance of the websites (hosting);
• Support of mailboxes or virtual mail servers;
• Placement of the customer's equipment on the service provider site;
• Rent of virtual dedicated and virtual private servers (VDS or VPS);
• Data Backup;
• and others.

Internet providers can be divided into several types according to  the services they provide:
• Access providers;
• Hosting providers;
• Backbone  providers;
• Channel providers;
• Last mile providers;
• and others.



In order to ensure compatibility of different networks and their component, Defense Advanced Research Projects Agency (DARPA) invented  a Transmission Control Protocol/Internet Protocol (TCP / IP) during 1970s.

TCP / IP is a set of network protocols according to which computers establish communication with each other. The Internet Protocol Suite is just snippets of code installed on the operating system and open up access to the protocols. TCP / IP is the standard, so the TCP / IP applications on the computer with Windows OS are able to successfully communicate with the same applications installed on the UNIX machine. During the initial period of network development, in 1983, engineers have developed a seven-layer Open Systems Interconnection (OSI) model to describe the process of network communication between the computers. The OSI model consists of physical, data link, network, transport, session, presentation and application levels. Administrators, who constantly work with the Internet and TCP / IP, mainly deal with the network, transport and application layer, but for a successful trouble shooting it is necessary to know the other levels.

Only 13% (570 million addresses) remained
in the global free pool as of 2008.

Internet Protocol Version 6 (IPv6) is a version of the Internet Protocol that was designed to improve Internet Protocol version 4 (IPv4). A number of limitations were removed from version 6, such as the length of the IP-address increased from 32 to 128 bits (i.e., it expanded to 340 trillion addresses), which solves the exhaustion problem of the available address space. In order to improve the performance of routers IPv6 introduces advanced packet headers, enhances protection of information (such as embedded encryption algorithm with a 64-bit key), simplifies the process of device configuration (introduced a feature of autoconfiguration). It became possible to assign priority levels to packets. In addition, IPv6 is upward compatible with IPv4.

Version of IPv6 is designed to develop and expand the Internet in order to ensure openness of information, both for providers and users. It is important to note that the introduction of IPv6 allows not only significantly reduce operating costs, but also expand the range of services.

Due to a rapid development of the Internet technologies, online analogs were provided for many offline services. For instance, regular phones now compete with Voice over IP (VoIP)  telephony. VoIP is a communications system, providing a transmission of the speech signal over the Internet or any other IP-based networks. 


Works Cited: http://www.personal.psu.edu/dvm105/blogs/ipv6/2009/01/  
http://www.youtube.com/watch?v=QDNxVwQwj2U 
http://en.wikipedia.org/wiki/TCP/IP_model 
http://en.wikipedia.org/wiki/Internet_service_provider