Chapter 4Networking and the Internet

Introduction to CS

1st Semester, 2015 Sanghyun Park

Outline Network Fundamentals Internet World Wide Web Internet Protocols Security (skipped)

Network Classification (1/3) Two broad categories

____ (Local Area Network):normally consists of a collection of computers in a single building or building complex, e.g., university campus

____ (Wide Area Network): links machines that may be in neighboring cities or an opposite side of the world

Ownership Public domain _____ network (Internet) Private entity ______ network or _________ network

Network ________ (pattern in which machines are connected) Ring, bus, star, irregular

Network Classification (2/3)

The machines are connectedin a ________ fashion

The machines are all connectedto a common communication line

called a _____

Network Classification (3/3)

One machine serves as a ____ to whichall the others are connected

The machines are connected in whatappears to be a _________ manner

Bridge and Router (1/2) At times it becomes necessary to ________ two existing networks

When the networks are compatible, this can be done by merely connecting the networks by a coupling device called a _______

When two networks are connected via a bridge, the result is simply a larger _______ network

It is often necessary to join two networks whose characteristics are not compatible

In this case, the two networks must be connected in a manner that builds a network of networks, which is known as an _______

The connection between two networks to form an internet is handled by a machine known as a ______

Bridge and Router (2/2)

Inter-Process Communication Client-server

One server, many clients Server must execute _____________ _______ initiates communication

Peer-to-peer Two processes communicating as _______ Peer processes can be ___________

Client/Server Model

C/S Model Compared ToPeer-To-Peer Model

Distributed Systems Systems with parts that run on _________ computers

Infrastructure usually provided by standardized toolkits

Examples include: Enterprise JavaBeans from ________________ .NET framework from ___________

The Internet A network of networks ________

An example of an internet is the _________

Originated from a research program initiated in 1973 by the Defense Advanced Research Projects Agency (DARPA)

Internet is a combination of WANs and LANs involving maybe millions of machines

Internet Topology (1/2) The Internet can be viewed as a collection of _______, each of which

is relatively small internet operated by a _______ organization

To establish a domain, the entity desiring the domain must register with ______ (Internet Corporation for Assigned Names and Numbers)

A domain is attached to the existing Internet via a _______ that connects a network in the domain to a network already in the Internet

This particular router is called the domain’s _________

The gateways of a number of domains can be connected to form a regional network of gateways

Internet Topology (2/2) A typical approach to connecting to the Internet

Internet Addressing (1/2) Each machine in the Internet is assigned a unique address,

called an ___ ________

Each IP address is a pattern of _______ consisting of two parts: Identify the domain (______________) Identify the particular machine within the domain (_____________)

Network identifier is assigned by ICANN at time of domain establishment and registration (guarantees __________ of network identifier)

The host address is assigned by the domain’s local authority

Example 192.207.177 (network identifier of Addison-Wesley publishing co.) 192.207.177.133 (a machine within this company)

Internet Addressing (2/2) ICANN assigns each domain a unique __________ address

known as domain namedomain name (edu, gov, org, com, … first-level domains)

Break domain into sub-domains

We need a ________ between numeric addresses and mnemonic addresses (each local authority maintains such _________)

Directory is implemented within the domain in the form of a server called a ____________ (DNS Domain Name System)

Name server provides ________ for mnemonic addresses to obtain the corresponding numeric addresses

World Wide Web (1/3) _________ is a text containing words, phrases, or images that are

linked to other documents When hypertext contains sounds and video, it is called

__________ Reader of hypertext documents can explore related documents A _____ of related information is formed Web that has evolved on the Internet spans the entire globe and is

known as ________________

Client machineBrowser

Server machineServes web pages

Request

Reply

World Wide Web (2/3) Each document is identified by a _________ address This unique address is called a _____ (Uniform Resource Locator) The URL allows to identify the ______, the ________ in use, and a

desired _________ Sometimes a URL does not explicitly identify a document, in such

case a predetermined document is often returned(usually a ______ page)

World Wide Web (3/3) A hypertext document contains several ________ that describe

How the document should _______ within the browser Which items within the document are to be ______ to other documents

Systems of markers known as Hypertext Markup Language (____) Finding information on the WWW ________ Engines

Layered Approach to Internet Software (1/2)

A principal task of network software is to provide the ___________ required for ___________ message from one machine to another

Package-shipping example

The transportation of the gift would be carried out by a three-level hierarchy:(1) the _____ level, (2) the ________ company, and (3) the ________

Layered Approach to Internet Software (2/2)

The Internet software has _____ layers rather than three:

TCP/IP Protocol Suite (1/2)

The _______ protocol suite is a collection of protocols used by the Internet to implement the four-level hierarchy just described

Actually, TCP (Transmission Control Protocol) and IP (Internet Protocol) are the names of only two of the protocols in this collection

TCP/IP protocol suite provides two ways of implementing the _______ layer: TCP and UDP (User Datagram Protocol)

The _________ layer may choose to send data via a TCP or UDP

IP is the Internet’s standard for the _________ layer

TCP/IP Protocol Suite (2/2)