TCOM 509 – Internet Protocols (TCP/IP)

Lecture 01

Instructor: Dr. Li-Chuan Chen lichen@mitre.org

TA: Waqar Ishaq wishaq@gmu.edu

Date: 08/25/2003

Based in part upon slides of Prof. J. Kurose (U Mass), Prof. B. Yener (Rensselaer Polytechnic Institute)

Topics - Tentative

Concepts Overview (1 lecture) IP Protocol (2 lectures) TCP/UDP (1 lecture) Routing Protocols (1 lecture) Internet Multicasting (1/2 lecture) Application Protocols (1/2 lecture)

Grading

Homeworks 30% Midterm 30% Final Exam 40%

Grades will be curved. No late homeworks will be accepted.

Outline

Introduction and Overview Internetworking Concept and

Architectural Model

Internet: History

U.S. Department of Defense had multiple networks.

Advanced Research Projects Agency (ARPA) funded research on packet-switched networking.

Late 60’s - ARPANET went on-line with point-to-point leased line interconnection.

The goal was to interconnect all machines at different sites so that researchers could share data and their findings across the ARPANET.

ARPA researchers designed networking software called TCP/IP Internet Protocol Suite or TCP/IP in the mid 70’s.

Internet: History

1983 - Defense Communications Agency (DCA) mandates all computers connected to backbone Internet use TCP/IP.

1983 - commercial implementation of TCP/IP begins. ARPA reached over 90% of university computer science

department by funding UC Berkeley to integrate TCP/IP into UNIX.

1983-1993: Internet changed from a small experimental research project into the world’s largest computer network.

By late 1987, estimated the growth rate had reached 15% per month. By 2000, the global Internet reached over 50 million computers in 209 countries. Both the size and the use of the Internet continued to grow much faster than anticipated.

Internet Host Count

Exponential Web Growth

Source: http://wcp.oclc.org/

Number of Web Sites:

1997: 1,570,000

1998: 2,851,000

1999: 4,882,000

2000: 7,399,000

2001: 8,745,0000

50000

100000

150000

200000

250000

Num of web sites

Source: Network Wizards

What are Internet Standards and RFC?

All activities on the Internet are governed by the Internet standards.

Who makes up these standards? How they are organized? Where to find these standards? What is RFC?

The Internet Architecture Board (IAB)

IAB decides which protocols are a required standard of the TCP/IP suite, sets official policies, and guides the evolution of the Internet.– Internet Research Task Force (IRTF) – coordinates research

activities– Internet Engineering Task Force (IETF) – short-term and medium-

term engineering problems

The Board

IESGIRSG

research groupsworking groups

… area n

…

area 1

…

…

The IAB Organization

IRTF IETF

What is RFC?

RFCs – Request For Comments– Most protocols of the TCP/IP are specified by

RFCs– Internet Engineering Steering Group (IESG)

edits and approves the RFCs. RFCs publications are for the Internet

community. RFCs are published by the IAB and are

freely available online. Internet drafts are preliminary versions

of RFC documents.

Internet Services

Internet is a set of applications that use the underlying network to carry out communication tasks.

Popular Internet application services are:– World Wide Web or Web allows users to view

multimedia documents and to follow hyper links from one computer to another.

– Electronic Mail or E-mail allows a user to compose and send messages to other individuals or groups on the Internet.

– File Transfer application allows users to send or receive a coy of a data file.

Will discuss these applications in greater detail later.

Internet Services Internet provides a connectionless or

connection-oriented packet delivery service for transporting data across network.

Data is divided (fragmented) into smaller pieces called packets. Packets may take different routes from a given source to a given destination.

Connectionless– No guaranteed delivery of packets. Packets may

arrive out-of-order. Connection-oriented

– Reliable transmission of packets delivery. Will retransmit packet if errors (transmission error, lost packets, hardware failure).

The Problem Before Internet: different packet-switching networks

– Proprietary communication systems: only nodes on the same network could communicate.

The Internetworking Problem

Two nodes, A and B, communicating across a cloud of networks– How to transport packets through this

heterogeneous networks?

BA

The Internetworking Problem

Problems: heterogeneous networks and systems, interoperability, and scalability

Heterogeneous networks and systems– How to interconnect a large number of disparate

networks ? – How to support a wide variety of applications ?

Interoperability– How to interoperate between various vendors’ products?

Scalability– How to support a large number of end-nodes and

applications in this interconnected network (Internet)?

Internetworking Solution

IP Gateways

Definitions

A network is a collection of hosts and nodes (routers, switches, or gateways) interconnected by communication links.

Protocols are standards which specify the procedures for passing messages, the details of message formats and describe how to handle error conditions.

A gateway interconnects two disparate networks, translates protocols, and forwards packets from one to the other.

Outline

Introduction and Overview Internetworking Concept and

Architectural Model

Network-Level Interconnection

FTP – File Transfer Protocol SMTP – Simple Mail Transfer Protocol HTTP – World Wide Web protocol

Application

TransmissionMedia

Telnet

Coaxial cable

Optical fiber

FTP SMTP

PacketRadio

HTTP

Not scalable – Each new application has to be re-implemented for every transmission media.

Network-Level Interconnection

TransmissionMedia

Application

Coaxial cable

Optical fiber

Telnet FTP SMTP HTTP

Advantages– Efficient: mapping packets directly onto network media– Flexible: adding or modifying network software without

the need for changing the application software.– Hides low-level details from the user.

InternetLayer (IP) IP

PacketRadio

Properties of the Internet

Interconnects all computers by assigning a universal unique IP address.

Universal interconnection - allows any two nodes to communicate irrespective of their network architectures, network topologies, and distance.

Internet Architecture

Net 2

Net 1

Net 3

R1

R2

• A collection of cooperative, interconnected networks by IP gateways or routers (Ri).

• IP routers provide interconnections among physical networks.• Routers use the destination network, not the destination computer, when forwarding a packet.

• All networks are equal. A network can be a local area network (LAN), a wide area network (WAN), or a point-to-point link between two computers.

Internet Architecture – User’s View

internethosts

Internet Architecture

hosts

Internetworking Protocols