Transcript Slaid_05 - narod.ru

Series of lectures
“Telecommunication networks”
Lecture#06
Data transmission
networks
Instructor: Prof. Nikolay Sokolov, e-mail: [email protected]
The Bonch-Bruevich Saint-Petersburg State
University of Telecommunications
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
Data Link
Mainframe
Mainframe
a) Connection between two mainframes
Terminal
Subscriber Line
Terminal
Subscriber Line
Mainframe
Terminal
Subscriber Line
b) Connections for terminals
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. 1968 - DARPA (Defense Advanced Research
Projects Agency) contracts with BBN (Bolt,
Beranek & Newman) to create ARPAnet
II. 1970 - First five nodes:
• UCLA
• Stanford
• UC Santa Barbara
• U of Utah, and
• BBN
III. 1974 - TCP specification by Vint Cerf
IV. 1984 – 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 Russia’s 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 organization’s 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. It’s enough to point out in the inquiry line a few key words determining
the area of the user’s 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.
Server’s main task is the transmission of the site’s 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; it’s 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, e-mail, 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, e-mail, 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, e-mail, 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, e-mail, 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, e-mail, 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, e-mail, 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, e-mail, 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, e-mail, 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
AS1
AS2
AS3
AS5
AS4
AS – Internet autonomous system
Interconnection of two local networks
R
R
R
R
LAN
LAN
R
R
R
R
R
R – router, LAN – Local Area Network
Internet influence on the
infocommunication system
Internet information system, Internet network
Telecommunication network
Society
Social environment
Individual
Economy
Perspective infocommunication system
Some aspects of the
Internet evolution
Main directions of the Internet development
Users working conditions
improvement
Provision of the new service
types
Creation of the system
management mechanisms
Broadband access
Text translation from
other languages
Security
.
.
.
.
.
.
.
.
.
Mobility
“Intellectual” help
Introduction of the
rational censorship
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.
http://www.internet2.edu/
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.
http://www.internet2.edu/
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.
http://www.internet2.edu/
Internet2 (4)
Structure of the network Abilene
OC-48c – 2488.32 Mbit/s, OC-192c – 9953.28 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
Traffic
Data
?
Voice
Time
Forecast of the access demands
Households, %
100
80
Sources: Alcatel Telecommunications Review, 2nd Quarter 2003,
Telektronikk, Volume 100, No. 4, 2004.
100 Mb/s
60
24 Mb/s
40
6 Mb/s
1.5 Mb/s
20
Year
1995
2000
2005
2010
2015
2020
2025
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 Canada’s 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 2008.
'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.
Data transmission networks
Questions?
Instructor: Prof. Nikolay Sokolov, e-mail: [email protected]