Two Or More Computers Communicating for the Purpose of Sharing Valuable Resources

Lecture Notes – CGS1570 - KBrown

Definitions/Terminology:

Network = . two or more computers communicating for the purpose of sharing valuable resources . valuable resources: o peripherals o data o software - applications o people - (teams - groupware)

Internet = . a “technology” for linking LANs into WANS . “a network of networks” . links local networks together into an expansive global network . by means of a common communications protocol

Protocol = . “set of rules” …on how to communicate . which allows o interoperability o cross-platform compatibility o cross-platform transparency

LAN = Local Area Network . generally linked w/in a small geographic area (building, campus)

MAN = Metropolitan Area Network . implies high speed direct connections (within a city) o often across fiber optic connections - (155 Mbps)

WAN = Wide Area Network . implies a communications link (phone, microwave, satellite) . Internet is a WAN

ISP = Internet Service Provider . agent providing dial-up or direct connections to the Internet, usually for a fee

ASP = Application Service Provider (business apps delivered)

D:\Docs\2017-12-13\0da123f0bd30dac91348ec36f19703c0.doc Lecture Notes – CGS1570 - KBrown

Additional Terms to investigate:

Web Page Web Server Web Browser

Hyperlink Hypertext HTML = Hypertext Markup Language Applet Intranet

Navigator elements to know: Location toolbar Navigation toolbar Bookmarks URL Buttons: Back Forward Stop Home Reload Netscape logo Progress bar Status message field

USES of the Internet -- Services or Capabilities

. E-Mail - o most popular use o requires a mail server

. WWW - World Wide Web o system for storing, retreiving, and displaying multimedia documents on computers all over the world . text . sound . pictures . video . graphics o requires a common presentation format . HTML = hyper-text markup language  provides common tags for presenting documents and links to other documents o requires a common protocol . http: = hypertext transport protocol . http: = native transport protocol on the Web o is a database of multimedia documents that spans the globe o requires a web server (server software) o requires a web browser (client application) to view these documents

. Information Retrieval o for accessing information o using search engines, directories, indexes to find information

. File Transfer = FTP scheme o moving files to & from servers – upload & download o as ASCII (text) or binary (program) files

. E-Commerce – buying & selling …usually on the Web . Newsgroups – distributed online bulletin boards (Usenet)

. IRC = Internet Relay Chat – real-time text-based conversations . Games – real-time video-based “conversations”

. INTRANets -- using e-mail & Web technology internally

Network Communication – How does it work?

“packet switching” theory is the key  information is handled in small, uniform, standardized packets that pass between computers & components on “best route” pathways  packet = envelope (of predetermined size and format) (use postal service/UPS mail examples)  network moves the packet to destination based on address  information within packet is not interpreted until destination  “connectionless” - packets move along “best route” per packet ( phone = circuit switched, physical, end-to-end connection per session)

NIC = Network Interface Card (Adapter)  the hardware that defines the “address” of the component  unique address – 12 hex digit MAC address (Media ACcess) by vendor  when powered on, (00-c0-ac-34-56-78) (8bit-8b-8b-8b-8b-8b)=48bit o announces itself & receives an reply of acknowledgement based on the protocol running o if TCP/IP, receives an IP address . (like a 9-digit zip code for ease of routing) . IP address can be linked to a “machine name” by means of DNS (domain name services) 139.62.115.23  jsmith.cocse.unf.edu (allows you to remember names of locations easier)

LAN Protocols: Appletalk = MacIntosh IPX/SPX = Novell NetBeui = OS/2 LAN Server; MS WinNT TCP/IP = core Internet protocol suite (native Unix protocol)  Transmission Control Protocol/ Internet Protocol  the protocol suite includes over 100 protocols o FTP o http o IP o telnet …  TCP – guarantees delivery of an IP packet (255.255.255.255)  IP = the Internet’s addressing scheme ….32bit = (8bit.8bit.8bit.8bit) o defines how each node can be uniquely identified o 4 part “dotted decimal” address XXX.XXX.XXX.XXX o addr based on the class license of the ISP (UNF = class B)

InterNIC – Domain Name Registration service organization (Dept of Commerce)

D:\Docs\2017-12-13\0da123f0bd30dac91348ec36f19703c0.doc