iap 04 internet history,tcpip

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University of education township campus lahore, Pakistan

Lecture 04

Overview of Internet Architecture

Internet Architecture and Protocols, University of education township campus lahore, Pakistan

Internet Architecture and Protocols

2Internet Architecture and Protocols, University of education township campus lahore, Pakistan

Layered Architecture• Design Philosophy of Layered Architecture

– The complex task of communication is broken into simpler sub-tasks or modules

– Each layer performs a subset of the required communication functions

– Each layer relies on the next lower layer to perform more primitive functions

– Each layer provides services to the next higher layer

– Changes in one layer should not require changes in other layers

– Helps in troubleshooting and identifying the problem

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TCP/IP PROTOCOL SUITETCP/IP PROTOCOL SUITE

The layers in the The layers in the TCP/IP protocol suiteTCP/IP protocol suite do not exactly match do not exactly match those in the OSI model. those in the OSI model.

The original TCP/IP protocol suite was defined as having four The original TCP/IP protocol suite was defined as having four layers: layers: host-to-network, internet, transport, and applicationhost-to-network, internet, transport, and application. .

However,However,

when TCP/IP is compared to OSI, we can say that the TCP/IP when TCP/IP is compared to OSI, we can say that the TCP/IP protocol suite is made of five layers: protocol suite is made of five layers:

physical, data link, network, transport, and application.physical, data link, network, transport, and application.

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TCP/IP and OSI model

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ADDRESSINGADDRESSING

Four levels of addresses are used in an internet Four levels of addresses are used in an internet employing the TCP/IP protocols: employing the TCP/IP protocols: physicalphysical, , logicallogical, , portport, , and and specificspecific..

Physical AddressesLogical AddressesPort AddressesSpecific Addresses

Topics discussed in this section:Topics discussed in this section:

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Addresses in TCP/IP

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Relationship of layers and addresses in TCP/IP

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In Figure a node with physical address 10 sends a frame to a node with physical address 87. The two nodes are connected by a link (bus topology LAN). As the figure shows, the computer with physical address 10 is the sender, and the computer with physical address 87 is the receiver.

Example-1

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Physical addresses

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Most local-area networks use a 48-bit (6-byte) physical address written as 12 hexadecimal digits; every byte (2 hexadecimal digits) is separated by a colon, as shown below:

Example-2

07:01:02:01:2C:4B

A 6-byte (12 hexadecimal digits) physical address.

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Figure shows a part of an internet with two routers connecting three LANs. Each device (computer or router) has a pair of addresses (logical and physical) for each connection. In this case, each computer is connected to only one link and therefore has only one pair of addresses. Each router, however, is connected to three networks (only two are shown in the figure). So each router has three pairs of addresses, one for each connection.

Example -3

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IP addresses

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The physical addresses will change from hop to hop,but the logical addresses usually remain the same.


Internet Protocol Stack

Application

Transport

Network

Data Link

Physical


TCP/IP Protocol Suite• Application Layer

– Responsible for supporting network applications– Protocols include: HTTP. SMTP, FTP etc.

• Transport layer (End-to-end Communication)– Two transport layer protocols (TCP and UDP)– Transports messages between client and server

applications• Network Layer (Host-to-host Communication)

– Routing of datagrams from one host to another– IP works on this layers

• Data link Layer (Node-to-node Communication)– Logical interface between end system and network– Examples: Ethernet, PPP, ATM and Frame Relay

technologies• Physical Layer

– Transmission medium– Signal rate and encoding

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OSI verses TCP/IP Model

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Data Encapsulation and PDU

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Protocol Data Unit (PDU)A unit of data which is specified in a protocol of a given layer and which consists of protocol-control information and possibly user data of that layer

↗It refers generically to a group of information added or removed by a particular layer of the OSI model↗Each layer uses the PDU to communicate and exchange information↗The PDU information is only read by the peer layer on the receiving device and then stripped off, and data is handed over to the next upper layer

↗Layer 1 (Physical Layer) PDU is the bit↗Layer 2 (Data Link Layer) PDU is the frame↗Layer 3 (Network Layer) PDU is the packet↗Layer 4 (Transport Layer) PDU is the segment↗Layer 5 and above are referred to as data

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PDUs in TCP/IP


Some Protocols in TCP/IP Suite


History of Internet• In 1960s the telephone network was the worlds

most dominant communication network• Uses Circuit switching which is appropriate for

voice traffic by supporting constant data rates• With the increasing importance of computers, the

need for interconnecting different geographically dispersed computers was realized.

• Three research groups laid the foundations of packet switching notion for computers communications:– MIT (Leonard Kleinrock)– Rand Institute (Paul Baran)– National Physical Laboratory (NPL)


History of Internet• Idea of Packet Switching• Principles of Packet Switching were conceived in

1957 by Paul Baran and others.• 1961--- First Paper by him on Packet Switching• 1964--- First Book on Internet in which Idea of

Packet Switching was declared more efficient than Circuit Switching

• Paul Baran used first time Digital Computer Technology for Communication between Switching Networks and divided the data into “Message Blocks” and reassembled at destination with some error detection technique

• Dynamic Routing of these Message Blocks was also proposed by Baran

• 1968--- First Packet Switching Network was designed and Implemented


The Internet’s Infancy: 1960s

• DARPA (Defense Advanced Research Project Agency) was established as an outcome of the Sputnik1 launch in 1957 by NASA (National Aeronautics and Space Administration), formally known as ARPA

• Computers in the form of Network was visualized and Implemented for data communication by Taylor

• 1966--- First Wide Area Computer Network was developed

• 1967--- First Packet Switching Router in the form of IMP (Interface Message Processor) was proposed; about a size of refrigerator

• 1968--- BBN designed IMPs and established the protocols allowing IMPs to communicate with each other.



• 1969--- Network Working Group (NWG) was formed to ensure the stability of communication protocols. Steve Crocker wrote first minutes of meetings

• IMP1: The first node of the ARPANET – http://www.lk.cs.ucla.edu/LK/Inet/birth.html

• The IMPs (Interface Message Processors) connected both host computers and other IMPs and functioned to:– Receive data– Check for errors– Retransmit, if error exists– Route the packets– Verify that packet are sent to intended receivers



• This documents was called RFC (Request for Comments) to take suggestions from peoples; later it became a Standard

• NWG designed first host-to-host protocols for host to IMP and computer to computer communication

• 1969--- Device Drivers were proposed to enable communication between different operating systems and hardware

• The destination IMPs used hop-by-hop acknowledgements. Since the source systems were different, so a software had to be designed to enable them to communicate, which is called a device driver


The Internet Early Years: 1970s

• 1970--- NCP (Network Control Protocol) was designed; used Stop and Wait flow control.It was the first host-to-host communication protocol that is used between the ARPANET end systems

• 1972--- Idea of Open-Architecture Network was floated

• 1973--- TCP (Transmission Control Flow Control) was designed for data transmission and Checksum was used for error detection


The Internet Early Years: 1970s

• Protocol Stack

APPLICATION

NCP

DEVICE DRIVER

IMP


The Internet Growth Begins: 1970 - 1980s

• 1973--- Ethernet was proposed as a LAN Technology

• 1974 --- First Ethernet protocol was developed• 1978 --- IP was proposed for Addressing purposes• 1980--- TCP/IP Protocol Suite was designed• UNET: First TCP/IP product was introduced for

Ethernet• BSD (Berkeley Software Division) Unix Operating

System was introduced• 1st January 1983--- It was decided to replace

NCP to TCP/IP for all Networks that gives birth to INTERNET

• 1983--- FTP, SMTP, DNS were introduced


The Internet Growth Begins: 1980s

• UDP comes into play for Real time Applications like Voice and Video

• 1984--- USENET modified for Newsgroups• 1986--- All Super Computers were connected to

form a Backbone Network called NSFNET which started from 56Kbps and in 1988 was converted to T1 Line I.e., 1.544Mbps

• 1988--- First Internet Worm was invaded effecting around 60,000 Hosts

• 1992--- WWW was created by Berners-Lee who also created First Web Server and Browser (Also designed HTTP later)

• 1993--- Clinton received first email at [email protected]

• 1993---- First Real Web Browser called MOSAIC was introduced


Internet Privatization: 1990s• 1994--- E-business started at Internet

• NSFNET decided to Privatize Internet by creating 4 NAPs (Network Access Points) and giving permission to ISPs to connect to NAPs

• 1995--- NSF Created High Speed Backbone Network Service to provide high-bandwidth connectivity (155 to 622Mbps) among NSF’s SCCs (Super Computer Centers)

• Internet2 was Created by Connecting all Top 100 Universities to these SCCs via GigaPOPs (Gigabits point of presence)

• Internet2: It is Hybrid Network whose Members are Major Universities and Research Organizations.

• Several Access Speed Transitions from 56Kbps Modem to ISDN (64-128Kbps), DSL Asymmetric Service to Cable Modems etc.

iap 04 internet history,tcpip

Technology

upper layer layer

physical layer pdu

frame layer

packet layer

network layer pdu

peer layer

lower layer

segment layer