Lecture#06 Data transmission networks The Bonch-Bruevich Saint-Petersburg State University of Telecommunications Series of lectures Telecommunication networks Instructor: Prof. Nikolay Sokolov,

Definition At present time "data transmission" term is often used for description of the different information exchange processes. Earlier this term was used for information intended for processing in the computer or for information already processed by the computer techniques means. In the ITU-T X.902 Recommendation (edition of the 1995) the "data" term definition was given as follows: "The representation forms of information dealt with by information systems and users thereof". Transformation of the term is related to processes of integration and convergence in the modern infocommunication system. In some cases, term "information and communications technology" (ICT) is used instead of infocommunications".

First data transmission systems for the mainframe

Internet Engineering Task Force (IETF) The Internet Engineering Task Force (IETF) is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. It is open to any interested individual. The IETF Mission Statement is documented in RFC 3935 (RFC – Request for Comments). The goal of the IETF is to make the Internet work better. The mission of the IETF is to produce high quality, relevant technical and engineering documents that influence the way people design, use, and manage the Internet in such a way as to make the Internet work better. These documents include protocol standards, best current practices, and informational documents of various kinds.

Internet (RFC 3935 ) The Internet: A large, heterogeneous collection of interconnected systems that can be used for communication of many different types between any interested parties connected to it. The term includes both the "core Internet" (ISP networks) and "edge Internet" (corporate and private networks, often connected via firewalls, NAT – network address translation – boxes, application layer gateways and similar devices). The Internet is a truly global network, reaching into just about every country in the world. The IETF community wants the Internet to succeed because we believe that the existence of the Internet, and its influence on economics, communication, and education, will help us to build a better human society.

Internet (other definitions ) The largest network of networks in the world. Uses TCP/IP protocols and packet switching. Runs on any communications substrate. The internet as we know it today is actually a very large wide area network (WAN) connecting computers and networks around the world. It makes it possible for millions of computer users to connect to one another via telephone lines, cable lines, and satellites.

Brief History of the Internet I DARPA (Defense Advanced Research Projects Agency) contracts with BBN (Bolt, Beranek & Newman) to create ARPAnet II First five nodes: UCLA Stanford UC Santa Barbara U of Utah, and BBN III TCP specification by Vint Cerf IV – On January 1, the Internet with its 1000 hosts converts en masse to using TCP/IP for its messaging.

Definition related to Internet (1) 1. Domain. Every country is assigned a certain code marking two-three Latin letters long, which is called first level domain. If the address ends with letters "ru", then corresponding site is situated in the Russias domain. There are also first level domains, which are related not with geography, but to the site orientation. For example, letters "com" are used for the commercial organizations, and letters "edu" are used for the educational institutes. Domains of the second level are rented to the organizations and private persons. Domain of the second level, as well as the next levels, must consist of the digits and Latin letters. When choosing domain of the second level for their site, as a rule, one usually strives to find a word that will correspond to the organizations name, produced goods or orientation of activity, and also is easy to read and remember. Second level domain possessor has a capability of creating unlimited number of third and so on level addresses. 2. Search engine. This system serves as an instrument for the information search in the Internet. Search engines differ in scope on local (for example, limited to national domain or certain language) and global (in particular, they qualitatively conduct USA sites search, where the significant part of the information resources is placed). Most part of the search engines does not require knowledge of the special request language. Its enough to point out in the inquiry line a few key words determining the area of the users interest. Texts are the main object for the search engines.

Definition related to Internet (2) 3. Site, Web-site. Site is the place in the Internet, which is determined by its address, has its own possessor and consists of several web-pages, which are apprehended as a single whole. Usually web-pages have identical design. There is no strict definition to the term site. For example, some parts of the big sites can be perceived and even defined by their possessors as individual sites. 4. Server, web-server. This term is used in three different meanings. Firstly, sometimes it is equivalent to the term "site". Secondly, computer, which provides site operation, is called server. Thirdly, sometimes the program which provides Web-site operation is called so. Servers main task is the transmission of the sites pages via http protocol (hypertext transfer protocol). 5. Web-page. Web page represents independent part of the Web-site. This document has unique address, which is well known by the abbreviation URL (uniform resource locator). 6. Host. There are several interpretations of this term. Mostly, any device (including PC), connected to the Internet and using TCP/IP protocol stack is called host. Rarely, by host mainframe is meant. 7. Web-browser. This program provides user with abilities of navigating and reviewing the Web-resources, downloading files and also with a number of other operations. 8. HTTP. Http protocol determines principles of the Web-pages transmission via the Internet network. At first http protocol was used only for transmission of the html-documents (hypertext mark-up language). At the present time, it is possible to transmit any information, including static images, sound and video by means of the http.

Definition related to Internet (3) 9. HTML. In that language browser (navigator) is informed just what the text and other elements (pictures, tables and etc.) exactly and how should be shown on the page. HTML is not programming language; its used for the special mark-up of the text, meant for the publishing in the Internet. HTML language allows cohering pages by means of links. Existence of the links is an important property of the Web pages. 10. IP-address. This address is used for the identification of the node in the network and for determining routing principles. Address consists of the network and host identifications (network and host ID), assigned by the network administrator. Network ID is a part of the IP-address, which determines group of the computers and devices of one logic network. Host ID is a part of the IP-address, which determines belonging of the computer to the certain network. Usually IP address is written in form of the four numbers with values from 0 to 255, separated by dots. 11. DNS-server. Main function of these special Web-servers is the storage of information about IP addresses and its transformation (DNS – domain name system). 12. URL (universal resource locator). This term is interpreted as the address of the page in the Internet. URL consists of domain name, path to the page on the site and the name of the page file. As a rule files containing Web-pages have "htm" or "html" extensions.

Internet functionality (1) WWW, , Telnet, FTP, Intranet, Extranet, Gopher, and Chat Group. It is a collection of millions of websites. A web site contains different web pages containing information. It organizes this information in such a way that user can easily search and access the required information.

Internet functionality (2) WWW, , Telnet, FTP, Intranet, Extranet, Gopher, and Chat Group. Standard for electronic mail. It is the exchange of messages and files using internet. Message can be in the form of graphics, sounds, video clips or simple text. It is the fast way of sending messages anywhere in the world in a very short time.

Internet functionality (3) WWW, , Telnet, FTP, Intranet, Extranet, Gopher, and Chat Group. A program that is used to connect to a remote computer on internet. A computer can act like a terminal directly linked to the remote computer. It allow a user to logon to a remote computer. The user can logon to the computer and use it as if he is connected to the computer directly.

Internet functionality (4) WWW, , Telnet, FTP, Intranet, Extranet, Gopher, and Chat Group. Used on internet for sending files from one place to another. Audio, video, graphics and data files can be uploaded or downloaded using this protocol. The process of transferring a file from remote computer to a local computer is called downloading. The process of transferring a file from a local computer is called uploading. Different software are available to use this protocol.

Internet functionality (5) WWW, , Telnet, FTP, Intranet, Extranet, Gopher, and Chat Group. It is a private and secure business network. It uses Internet technology to provide information to the employees of the organization. The information can be protected from unauthorized users. It is designed to meet the internal needs for sharing information within a single organization or company.

Internet functionality (6) WWW, , Telnet, FTP, Intranet, Extranet, Gopher, and Chat Group. It is a collection of two or more intranets. It can be accessed by authorized users from outside the organization. Different organizations can use extranet to share the information of their intranets. An organization can apply security measures to provide limited access to the employees of other organization using the extranet.

Internet functionality (7) WWW, , Telnet, FTP, Intranet, Extranet, Gopher, and Chat Group. A menu based system for exploring the internet and its resources. It provide the facilities for search and file retrieval on the internet. It organizes resources in such a way that finding information becomes easier on the internet.

Internet functionality (8) WWW, , Telnet, FTP, Intranet, Extranet, Gopher, and Chat Group. Exchanging view on the internet by typing text messages. It is a group of users with similar interest. Many users join chat group for exchanging views or talking for fun. The user can interact with one another in real-time. It mean that they are online at the same time.

SKYPE 1. Video and Voice Over Internet Protocol 2. Computer to computer calls everywhere are FREE! 3. For a small charge you can call from your Skype account to any phone. Skype In Education: Record a conversation with a scientist, Teach a lesson remotely, Have a group chat with students in a labs, Carry out online interviews with someone, Record the work of a conference session where students plan a project between two sites and turn in the recorded call, World language classes can practice speaking with students in another language, Connect students in rural areas.

Example of the Internet network structure AS – Internet autonomous system

Interconnection of two local networks R – router, LAN – Local Area Network

Internet influence on the infocommunication system

Some aspects of the Internet evolution

Internet2 (1) Who We Are Internet2 is a not-for-profit advanced networking consortium comprising more than 200 U.S. universities in cooperation with 70 leading corporations, 45 government agencies, laboratories and other institutions of higher learning as well as over 50 international partner organizations. Our organization is governed by an executive Board of Trustees and strategic councils consisting of leaders who represent our broad membership.

Internet2 (2) What We Do Internet2 members leverage our high-performance network and worldwide partnerships to support and enhance their educational and research missions. Beyond just providing network capacity, Internet2 actively engages our community in the development of important new technology including middleware, security, network research and performance measurement capabilities which are critical to the progress of the Internet.

Internet2 (3) Why We Do It We have only begun to discover the potential of Internet technology, not only to the important work of the research and education community, but to commerce and business, to healthcare and science, to the arts and humanities and beyond. Unlike any other organization of its kind, the Internet2 community pioneers the use of advanced network applications and technologies, from their academic inception through their evolution to the commercial Internet.

Internet2 (4) Structure of the network Abilene OC-48c – Mbit/s, OC-192c – Mbit/s, (OC – Optical Carrier)

Protocols (1) DoD – Department of Defense

Protocols (2)

Protocols (3)

Access to Internet (1)

Access to Internet (2)

Wide area network connection (1)

Wide area network connection (2) NTE – Network terminal equipment

Switching equipment

Examples of network structure (1)

Examples of network structure (2)

Traffic growth

Forecast of the access demands

Cost of Internet services

Internet in our life Research company Yougov carried out survey among broadband Internet users in Great Britain. The main goal was to define goods and services that citizens will be eager to sacrifice during economic depression. Approximately 3% of the respondents were ready to save money by limiting expenses on Internet access. About 30% of respondents (near 5 million) were ready to cut down expenses related to newspapers & magazines, alcohol, cigarettes but will use Internet. On the other hand, only 60% of respondents were going to use services from their Provider. Remainder will find Provider with inexpensive services.

Global internet traffic (1) Global internet traffic growth remains strong in 2010

Global internet traffic (2) Growth rates varied significantly by region. The regions experiencing the fastest growth in international Internet traffic between mid-year 2009 and mid-year 2010 were Eastern Europe and India/South Asia, where average traffic growth exceeded 100%, and the Middle East, where traffic rose just under 100%. Even relatively 'mature' markets are still growing rapidly: western European international Internet traffic increased 66%, and the US and Canadas international Internet traffic climbed 54%. 'Carriers must add enormous amounts of new capacity each year to accommodate such traffic growth,' said TeleGeography Research Director Alan Mauldin. In 2010, carriers added 13.2Tbps of new international capacity, up from 9.4Tbps in 2009, and 6Tbps in 'Thanks to these large increases in new bandwidth, traffic growth has not overwhelmed operators networks, and overall network utilization levels have remained stable,' said Mauldin.

Global internet traffic (3) While the pace of network expansion is fastest in developing markets, a vast gulf exists between the amount of international Internet bandwidth available to developing countries and developed markets. For example, at mid-year 2010, the country of Austria – with a population of just over eight million, had access to more international Internet capacity than the billion inhabitants of Africa, combined. Note: Some pictures used in this presentation may be found in Handbook of Data Communications and Networks written by William Buchanan.

Instructor: Prof. Nikolay Sokolov, Questions? Data transmission networks