Chapter 4 Networking and the Internet Introduction to CS 1 st 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 connected in a ________ fashion The machines are all connected to a common communication line called a _____

Network Classification (3/3) One machine serves as a ____ to which all the others are connected The machines are connected in what appears 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 To Peer-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  (network identifier of Addison-Wesley publishing co.)  (a machine within this company)

Internet Addressing (2/2) domain name  ICANN assigns each domain a unique __________ address known as domain 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 machine Browser Server machine Serves 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)