TCP/IP & INTERNET Unit 1 Department Of Computer Science & Engineering

Syllabus Introduction and Overview. Comparison of OSI Model and TCP/IP model. Networking Technologies: LANS, WANS, Connecting Devices. Internetworking concept and Architectural model. Internet Backbones, NAP, ISP’s, RFC’s, Internet Standards.

Learning Objectives Upon completion you will be able to: Understand how the Internet came into being Understand the meaning of the terms protocol and standard Understand the various organizations involved in the standards Understand the different levels of Internet service providers Understand the groups involved in Internet administration Understand the architecture of the OSI model Understand the layers of the OSI model and their functions Understand the architecture of the TCP/IP Protocol Suite Differentiate between the OSI model and the TCP/IP Suite Differentiate between the three types of Internet addresses Understand the different versions of wired Ethernet Understand wireless Ethernet Understand the types of point-to-point WANs Understand the types of switched WANs, especially ATM Differentiate between repeaters, bridges, routers, and hubs

Brief History of Internet A network is a group of connected, communicating devices. An internet is two or more networks that can communicate with each other. The most notable internet is called the Internet. Millions of people are users. Yet this extraordinary communication system only came into being in 1969.A network is a group of connected, communicating devices. An internet is two or more networks that can communicate with each other. The most notable internet is called the Internet. Millions of people are users. Yet this extraordinary communication system only came into being in 1969.

Today’s Internet

Protocols & Standards An Internet standard is a thoroughly tested specification. There is a strict procedure by which a specification attains Internet standard status. A specification begins as an Internet draft, working document with no official status and a six-month lifetime. A draft may be published as a Request for Comment (RFC).An Internet standard is a thoroughly tested specification. There is a strict procedure by which a specification attains Internet standard status. A specification begins as an Internet draft, working document with no official status and a six-month lifetime. A draft may be published as a Request for Comment (RFC).

Maturity levels of an RFC

Figure : Requirement levels of an RFC

OSI Model Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s.Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s.

Layers in OSI Model ISO is the organization.OSI is the model

OSI Layers

Layers of OSI Model Physical LayerPhysical Layer Data Link LayerData Link Layer Network LayerNetwork Layer Transport LayerTransport Layer Session LayerSession Layer Presentation LayerPresentation Layer Application LayerApplication Layer Summary of LayersSummary of Layers

The physical layer is responsible for the movement of individual bits from one hop (node) to the next. Figure : Physical layer

The data link layer is responsible for moving frames from one hop (node) to the next Figure : Data link layer

The network layer is responsible for the delivery of individual packets from the source host to the destination host. Figure : Network layer

The transport layer is responsible for the delivery of a message from one process to another. Figure : Transport layer

Session layer Figure

Presentation layer Figure

Figure : Application layer

Figure : Summary of layers

TCP/IP Protocol Suite The TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application. The first four layers provide physical standards, network interface, internetworking, and transport functions that correspond to the first four layers of the OSI model. The three topmost layers in the OSI model, however, are represented in TCP/IP by a single layer called the application layer.The TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application. The first four layers provide physical standards, network interface, internetworking, and transport functions that correspond to the first four layers of the OSI model. The three topmost layers in the OSI model, however, are represented in TCP/IP by a single layer called the application layer.

Figure : TCP/IP and OSI model

Addressing Three different levels of addresses are used in an internet using the TCP/IP protocols: physical (link) address, logical (IP) address, and port address.Three different levels of addresses are used in an internet using the TCP/IP protocols: physical (link) address, logical (IP) address, and port address.

Figure : Addresses in TCP/IP

Figure : Relationship of layers and addresses in TCP/IP

Figure : Internet model

Local Area Network (LAN) Local Area Network (LAN) A local area network (LAN) is a data communication system that allows a number of independent devices to communicate directly with each other in a limited geographic area such as a single department, a single building, or a campus. A large organization may need several connected LANs.The most popular LANs are Ethernet and wireless LANs.A local area network (LAN) is a data communication system that allows a number of independent devices to communicate directly with each other in a limited geographic area such as a single department, a single building, or a campus. A large organization may need several connected LANs.The most popular LANs are Ethernet and wireless LANs.

Figure : Ethernet layers

Figure : Ethernet frame

Point-to-Point WAN A second type of network we encounter in the Internet is the point-to-point wide area network. A point-to-point WAN connects two remote devices using a line available from a public network such as a telephone network. We discuss the physical and data link layers of these technologies here..A second type of network we encounter in the Internet is the point-to-point wide area network. A point-to-point WAN connects two remote devices using a line available from a public network such as a telephone network. We discuss the physical and data link layers of these technologies here..

Switched WAN The backbone networks in the Internet are usually switched WANs. A switched WAN is a wide area network that covers a large area (a state or a country) and provides access at several points to the users. Inside the network, there is a mesh of point-to-point networks that connects switches. The switches, multiple port connectors, allow the connection of several inputs and outputs.The backbone networks in the Internet are usually switched WANs. A switched WAN is a wide area network that covers a large area (a state or a country) and provides access at several points to the users. Inside the network, there is a mesh of point-to-point networks that connects switches. The switches, multiple port connectors, allow the connection of several inputs and outputs.

Figure : Architecture of an ATM network

Connecting Device LANs or WANs do not normally operate in isolation. They are connected to one another or to the Internet. To connect LANs or WANs, we use connecting devices. Connecting devices can operate in different layers of the Internet model. We discuss three kinds of connecting devices: repeaters (or hubs), bridges (or two-layer switches), and routers (or three-layer switches). Repeaters and hubs operate in the first layer of the Internet model. Bridges and two-layer switches operate in the first two layers. Routers and three-layer switches operate in the first three layersLANs or WANs do not normally operate in isolation. They are connected to one another or to the Internet. To connect LANs or WANs, we use connecting devices. Connecting devices can operate in different layers of the Internet model. We discuss three kinds of connecting devices: repeaters (or hubs), bridges (or two-layer switches), and routers (or three-layer switches). Repeaters and hubs operate in the first layer of the Internet model. Bridges and two-layer switches operate in the first two layers. Routers and three-layer switches operate in the first three layers

Figure : Connecting devices

A repeater connects segments of a LAN. A repeater forwards every bit; it has no filtering capability. A repeater connects segments of a LAN. A repeater forwards every bit; it has no filtering capability. A repeater is a regenerator, not an amplifier. Figure : Repeater

Figure Function of a repeater

A bridge does not change the physical (MAC) addresses in a frame. Figure : Bridge

A router changes the physical addresses in a packet. Figure : Routing example

Summary The internet is a collection of hundreds of thousands of separate networks. TCP/IP is the protocol suite for Internet RFC is an idea or concept that is precursor of Internet standard ISO is created a model called OSI. The seven layers of OSI model provide guidelines for development of universally compatible network protocols. TCP/IP is five layer hierarchical protocol suite developed before the OSI model Connecting devices are studied.

References TCP/IP Protocol suite, Behrouz A. Forouzan, Third Edition, TMH. Internetworking and TCP/IP: Principles, Protocols and Architectures, Douglas Comer, Pearson Education Computer Network by William Stallings