Getting Connected

Getting ConnectedCECS 5030

with Cathie Norris, Jennifer Smolka & Gerald Knezek

The Internet Today

Worldwide network of networks

Government agencies, educational institutions, hospitals, and commercial organizations

The Internet Today

Phenomenal growth - 1 million/month

End of 2001 – 500 million users

Largest connection of networks in the world

How the Internet Works

Local connection via modem, leased-line, ISDN, etc.

Router at provider’s point-of-presence

How the Internet Works

Small providers buy from big providers NorthwestNet NorthwestNexus

Big providers interconnect with each other MCI Sprint AT&T

MCI AT&T

NWNET NWNEXUS

The Internet uses TCP/IP

Share common protocol TCP/IP

Transmission Control Protocol/Internet Protocol

“/” means it operates at two levels

TCP IP

The Internet uses TCP/IP

Created more than thirty years ago by the Department of Defense Advanced Research Projects Agency (DARPA)

TCP/IP is the still the basis for the Internet

The Internet uses TCP/IP

IP Address – unique identifier

IP resides in the Network Layer

TCP resides in the Transport Layer

TCP/IP

Network Protocols Internet Protocol (IP)• Every computer on the Internet has a

unique number which is the destination point• Where you are and how I get there

Transmission Control Protocol (TCP)• How is my data getting between you

and me

TCP/IP

Application Protocols Terminal Emulation (Telnet) HyperText Transfer Protocol (HTTP) File Transfer Protocol (FTP) Simple Mail Transfer Protocol (SMTP) Simple Network Management Protocol

(SNMP) Domain Name Service (DNS)

TCP/IP in the OSI Model

ApplicationPresentationSessionTransportNetworkLogical LinkPhysical

FTP, Telnet

TCP UDPIP ARP

LLCEthernet, WAN, Token Ring, FDDI

SNMP TFTPNFS

Seven Layer Open System Interconnect Model

TCP/IP in the OSI Model

ApplicationPresentationSessionTransportNetworkLogical LinkPhysical

FTP, Telnet

TCP UDPIP ARP

LLCEthernet, WAN, Token Ring, FDDI

SNMP TFTPNFS

Internet Protocol (IP)

IP is a connectionless service that provides basic datagram delivery services.

IP takes care of addressing, or making sure the routers know what to do with your data when it arrives.

Internet Protocol (IP)

Not everything is sent over the Internet is not sent as a BATCH – or complete file

Sent over as packet of smaller pieces

256 characters or 512 characters (maybe longer)

Internet Protocol

Every computer on the Internet has a unique address.

Information sent across IP networks is broken up into bite-sized pieces, called packets.

The information within a packet is usually between 1 and about 1500 characters long.

IP Envelopes

From: 192.112.36.5

To: 128.174.5.6IP Packet

DATA

Internet Protocol

Some addressing information goes at the beginning of your message; this information gives your network enough information to deliver the packet of data.

Internet addresses consist of four numbers each less than 256.

192.112.36.5 128.174.5.6

Internet Protocol

IP Addresses Class A Networks: 128.x.x.x Class B Networks: 146.79.x.x Class C Networks: 192.100.10.x

IP addresses are running out - Extensions to the current IP address protocol will be required - IPng

Transmission Control Protocol

Reliable TCP takes the information you want to

transmit and breaks it into pieces. TCP numbers each piece so receipt can

be verified and the data can be put back in the proper order.

Acknowledgments

TCP Packet Encapsulation

DATA

To: 128.174.5.6

Bytes 1 to 500

TCP Packet

From: 192.112.36.5To: 128.174.5.6

IP Packet

SLIP and PPP

Extensions of IP over voice-grade modem lines:

Serial Internet Protocol (SLIP) Point-to-Point Protocol (PPP)

Allow internet access from the PC in your home by dialing up over modems to an Internet host.

TCP/IP Applications/Services

Terminal Emulation (Telnet)

File Transfer Protocol (FTP)

HyperText Transfer Protocol (HTTP)

Simple Mail Transfer Protocol (SMTP)

Simple Network Management Protocol (SNMP)

Domain Name Service (DNS)

Terminal Emulation (Telnet)

Telnet is the login and terminal emulation program for TCP/IP environments

Primary function is to allow users to log into remote host systems

Requires username and password

How to Telnet

Open your DOS prompt Type telnet Your telnet window opens...

Uses for Telnet Today

Use of Telnet has diminished in recent years

Still being used to: Connect to routers Remote management of

servers Access to home system

while traveling

File Transfer Protocol (FTP)

Important for building web pages

Primary mode of moving complete file from one computer to another

FTP is a program for transferring files in TCP/IP environments (ASCII or Binary)

File Transfer Protocol (FTP)

Client – when you want information

Server – when you have the information

Typically, a user at a client computer downloads files from a remote server

FTP Terms: DOS

GET (MGET): You are downloading a file (or files) from another computer to your desktop

PUT (MPUT): You are uploading a file (or files) from your desktop to another computer

File Transfer Protocol (FTP)

Must logon to server

Requires username and password to access normal file system

Anonymous FTP allows access to anyone to a special file system (e.g. ftp.microsoft.com)

FTP Terms: DOS

CD: Change Directory Move up or down the directory structure

MD: Make Directory New storage space

FTP Transparent

Often FTP commands are transparent through your browser or through a FTP

program like WS FTP.

HyperText Transfer Protocol

Primary application protocol that underlies the world wide web

Provides user access to the files that make up the web

Anywhere – anyplace – anytime

HyperText Transfer Protocol

Defines HOW they get there, not what they look like

Files can be in many different formats (text, graphics, audio, video, etc.)

Hypertext markup language (HTML) is the standardized language for creating web pages

Simple Mail Transfer Protocol

SMTP is the electronic mail transfer protocol used in TCP/IP environments

Provides a store-and-forward mail capability between host computer mail systems on the network

MIME (Multimedia Internet Mail Exchange) has become the standard for document attachments

Domain Name Service

DNS is a TCP/IP service that maps network address numbers, for example, 123.456.789, to an easy to remember name, such as:

Internet and TCP/IP applications such as telnet, FTP and SMTP access DNS to locate names you’ve specified and resolves them to a numeric address and inserts it into a message for transport.

www.microsoft.com

Domain Name Service

The address information is stored at many locations in a hierarchical structure, not at one central depository

Each site has a domain server that maintains information about the local nodes

Central Hub

Node Node

Node Node

Client/Server Architectures

Two-tier “Fat” Client: User Interface + Application Database Server Example: File servers, SQL Servers

Client/Server Architectures

Three-tier “Thin” Client: User Interface only Application Server Database Server Examples: Mail servers, Business

applications

Client/Server Architectures

Application Programming Interfaces SQL, ODBC APPC TP Monitors RPC

Interface Definition Languages DCE CORBA Microsoft OLE

References

From Networking 101Jim Cabral, Puget Technology Group, Inc. &

Tammy Ruth, Children’s Hospital and Medical Center

cabralje@pugettech.com truth@chmc.org

www.pugettech.com