Alfredo Digrillioni: -Introduction to Networking -OSI model Jalal Pirzada: -Topology and Access -Designs and software Aymin Matri: -Protocols -IP Addressing.

Alfredo Digrillioni: -Introduction to Networking

-OSI model Jalal Pirzada:

-Topology and Access-Designs and software

Aymin Matri:-Protocols

-IP Addressing Stephen Kurtz:

-Subnetting -Intranet

FUNDAMENTALS OF NETWORKING

1. NETWORK:

• INTERCONNECTION OF COMPUTERS LINKED TOGETHER USING A VARIETY OF DIFFERENT CONECTING MEANS.

• COMPUTERS ARE INTERCONNECTED FOR DIFFERENT PURPOSES.

2. REASONG FOR NETWORKING:

• TO SHARE RESOURCES (FILES, PRINTERS, MODEMS, FAX MACHINES)

• TO SHARE APPLICATIONS SOFTWARE

• TO INCREASE PRODUCTIVITY (TO MAKE EASIER TO SHARE DATA AMONGST USERS)

3. MOST COMMON TYPES OF NETWORKS:

• LANs (LOCAL-AREA NETWORKS)

• WANs (WIDE-AREA NETWORKS) COMPUTER ARE FARTHER APART AND ARE CONNECTED VIA TELEPHONE/COMMUNICATION LINES, RADIO WAVES, OR OTHER MEANS OF CONNECTION.

• THE INTERNET IS AN EXAMPLE OF THIS TYPE OF NETWORKING.

•

BRIEF HISTORY OF NETWORKING1. ARPANET (YEAR 1969) WAS AN EXPERIMENTAL NETWORK

CONNECTING THE MAINFRAME COMPUTERS OF UNIVERSITIES AND OTHER FEDERAL CONTRACTORS.

2. THIS PROJECT WAS FUNDED BY “ARPA” (ADVANCED RESEARCH PROJECT AGENCY OF THE U.S. DEPARTMENT OF DEFENSE)

2. INTRANETS EXPANSION OF CORPORATE & GOVERNMENT (PRIVATE) NETWORKS / NO ACCESS TO THE GENERAL PUBLIC.

3. INTERNET “NETWORK OF NETWORKS” / GLOBAL

4. ACCESIBLE TO EVERYBODY

4. INTERNATIONAL STANDARDS IN NETWORKING:

• IN 1983/1984 THE ISO (INTERNATIONAL STANDARDS ORGANIZATION) ADOPTED A CODIFICATION OF THE IDEAL NETWORK PROTOCOL STACK IN A SCHEME CALLED OSI (OPEN SYSTEM INTERFACE REFERENCE MODEL OR OPEN SYSTEM INTERCONNECTION MODEL)

• THE MODEL ALLOWS THE SENDING AND RECEIVING OF DATA BETWEEN TWO DISSIMILAR COMPUTERS, USING A LAYER APPROACH (EACH LAYER IS RESPONSIBLE FOR PERFORMING CERTAIN FUNCTIONS).

OSI MODEL

1. COMPUTERS CAN TRANSFER DATA BETWEEN THEMSELVES, WITHOUT RESTRICTIONS ON THE TYPE OF OF HARDWARE OR SOFTWARE USED.

2. DIVIDES NETWORKING SOFTWARE INTO A VERTICAL SEVEN-LAYER STACK, IN WHICH EACH LAYER HAS A DISTINCT FUNCTION.

3. MESSAGES BETWEEN TWO CONNECTED MACHINES ARE SENT DOWN THE STACK OF THE SENDING MACHINE, ACROSS THE NETWORK, AND UP THE STACK OF THE RECEIVING MACHINE.

4. WHY THE LAYER APPROACH ?

• SENDING DATA FROM ONE COMPUTER TO ANOTHER REQUIRES MANY DIFFERENT TASKS TO BE PERFORMED.

• DIVIDING THOSE FUNCTIONS INTO SEPARATE LAYERS MAKES WRITING THE RESPECTIVE SOFTWARE MUCH EASIER

DATA TRANSMISSION DATA RECEPTIONUpper Layers

7 APPLICATION LAYER

6 PRESENTATION LAYER

5 SESSION LAYER

Lower Layers

4 TRANSPORT LAYER

3 NETWORK LAYER

2 DATA LINK LAYER

1 PHYSICAL LAYER

PHYSICAL LINK

THE 7 LAYERS OF THE OSI MODEL

• OSI MODEL - SEVEN LAYERS

• LAYER 7 – APPLICATION LAYER

• PROVIDES APPLICATIONS WITH ACCESS TO NETWORK SERVICES.

• THE PROGRAMS WHICH USE SERVICES OF THE NETWORK RESIDE IN THIS LAYER.

• LAYER 6 – PRESENTATION LAYER

• DETERMINES THE FORMAT USED TO EXCHANGE DATA AMONG NETWORKED COMPUTERS.

• IT FORMATS DATA FOR THE PURPOSE OF DISPLAY OR PRINTING.

• LAYER 5 – SESSION LAYER

• ALLOWS TWO APPLICATIONS TO ESTABLISH, USE AND DISCONNECT A CONNECTION BETWEEN (CALLED A SESSION).

• PROVIDES FOR NAME RECOGNITION AND ADDITIONAL FUNCTIONS LIKE SECURITY WHICH ARE NEEDED TO ALLOW APPLICATIONS TO COMMUNICATE OVER THE NETWORK.

• LAYER 4 – TRANSPORT LAYER

• ENSURES THAT DATA IS DELIVERED ERROR FREE, IN SEQUENCE AND WITH NO LOSS, DUPLICATIONS OR CORRUPTION.

• THIS LAYER ALSO REPACKAGES DATA BY ASSEMBLING LONG MESSAGES INTO LOTS OF SMALLER MESSAGES FOR SENDING, AND REPACKAGING THE SMALLER MESSAGES INTO THE ORIGINAL LARGER MESSAGE AT THE RECEIVING END.

•

• LAYER 3 – NETWORK LAYER

• THIS LAYER IS RESPONSIBLE FOR ADDRESSING MESSAGES AND DATA SO THEY ARE SENT TO THE CORRECT DESTINATION, AND FOR TRANSLATING LOGICAL ADDRESSES AND NAMES INTO PHYSICAL ADDRESSES.

• THIS LAYER IS ALSO RESPONSIBLE FOR FINDING A PATH THROUGH THE NETWORK TO THE DESTINATION COMPUTER.

•

• LAYER 2 – DATA-LINK LAYER

• THIS LAYER TAKES THE DATA FRAMES OR MESSAGES FROM THE NETWORK LAYER AND PROVIDES FOR THEIR ACTUAL TRANSMISSION.

• IT ALSO PROVIDES ERROR-FREE DELIVERY OF DATA BETWEEN THE TWO COMPUTERS BY USING THE PHYSICAL LAYER: IT PACKAGES THE DATA FROM THE NETWORK LAYER INTO A FRAME WHICH INCLUDES ERROR DETECTION INFORMATION.

• AT THE RECEIVING COMPUTER, THE DATA-LINK LAYER READS THE INCOMING FRAME, AND GENERATES ITS OWN ERROR DETECTION INFORMATION BASED ON THE RECEIVED FRAMED DATA.

• AFTER RECEIVING ALL OF THE FRAME, IT COMPARES ITS ERROR DETECTION VALUE WITH THAT OF THE INCOMING FRAMES, AND IF

• THEY MATCH, THE FRAME HAS BEEN RECEIVED CORRECTLY.

•

• LAYER 1 – PHYSICAL LAYER

• CONTROLS THE TRANSMISSION OF THE ACTUAL DATA ONTO THE NETWORK CABLE.

• IT DEFINES THE PHYSICAL COMMUNICATION MEDIA (TYPE OF CABLE, FREQUENCY, TERMINATIONS, ETC.).

Network: Computers are connected to each other and to other devices (wired or wireless)

Major Types of Networks-Local Area Network (LAN): A network that connects computers that are

close to each other, usually in the same building, linked by a cable.

-Wide Area Network (WAN): A network in which computers are connected to each other over a long distance, using telephone lines and satellite communications.-largest WAN is the Internet-two or more LANs connected together

-Metropolitan Area Networks (MAN): A data network designed for a town or city.

-LAN, WAN, MAN uses Topology, Access (speed), and Designs but vary due to size & location

-Future: Wireless Networking (Blue Tooth) or Networking by Electrical Outlet

Basic Topologies

The configuration of a network; the ways computers are interconnected. Common

network topologies are

• Bus

• Star

• Ring

• Mesh

Bus Topology: Single cable connects all the computers in a line

Pros:

-Simple

-One Wire or Cable

Cons:

-Single point of failure can stop the entire network

-Slow and not efficient

Star Topology: Computers are connected to hub by a cable

Pros:

-One computer fails, the remainder function normally

Cons:

-If the hub fails, the entire network fails

Ring Topology: Computers are connected to a cable that

forms a circle around a central location Pros:

-Each computer acts as a repeater, regenerating the signal

-Handles high traffic environments better than a bus topology

Cons:

-Only one computer at time can send data on a single token ring

-More expensive

Mesh Topology: Computers on the network are connected to every other computer by cable

Pros:

-Backup capabilities, one cable fails info can still be passed

-Multiple LAN’s can be connected in a Mesh by leased telephone lines, or fiber optic lines

Cons:

-Redundant paths require more cabling, hence expensive

Accessing (Speed) The Network

• Ethernet

• Token Ring

• ATM (Asynchronous Transfer Mode)

• FDDI (Fiber Distributed Data Interface)

Ethernet

-The most popular type of local area network, which sends its communications through radio frequency

signals carried by a coaxial cable.

-Each computer checks to see if another computer is transmitting and waits its turn to transmit.

-If two computers accidentally transmit at the same time and their messages collide, they wait and send

again in turn.

Transfer Speed: 10mbps to 1Gibabit mbps

Token Ring

-A local area network in which computers are configured in a ring, and a message called a

token is passed from station to station.

-The token is used to avoid conflicts in transmission; a machine can only transmit

messages while it holds the token.

Transfer Speed: 4-16mbps for all cable types

ATM

1. Asynchronous Transfer Mode, a network technology that enables the transmission of data,

voice, audio, video, and frame relay traffic in real time.

2. Automatic Teller Machine, a bank terminal that lets customers deposit, withdraw cash, and perform other transactions electronically.

Transfer Speed: FiberOptic 155 to 622mbps

FDDI

Fiber Distributed Data Interface. An ANSI standard for 100 Mbit/s data

transmission through fiber optic cable, in a token ring setup.

Many local area networks can be linked together with a backbone that uses

FDDI.

Transfer Speed: FiberOptic 155 to 622mbps

Network Designs

• Workgroup • Client/Server

• Domain Based • Directory Based

Workgroup Two or more computer users working together on a project,

sharing data and files by means of a network.

Client/Server

An architecture in which one computer can get information from another.

The client is the computer that asks for access to data, software, or services.

The server, which can be anything from a personal computer to a mainframe, supplies the requested data or services for the client.

Software

• Network Operating System

-Windows NT or 2000

-Novell Netware

Protocols

Protocol

It is a set of rules that governs data communication. A protocols defines what is communicated, how it is communicated and when it is communicated. The key elements of a protocols are Syntax, Semantics and Timing.

Standards

• Standards are essential in guaranteeing national and international operability of data and telecommunication technology.

• They are developed through cooperation of standard creation committees, forums and government agencies.

Standards Creation Committees

• International Standards Organization (ISO)

• International Telecommunication Union- Telecommunication Standards Sector (ITU-T)

• American National Standards Institute (ANSI)

• Institute of Electrical and Electronic Engineers (IEEE)

• Electronic Industry Association (EIA)

IP Addressing

• An IP (Internet Protocols) address is a 32-bit address that uniquely defines a host or a router on the Internet.

• The IP addresses are unique in the sense that two devices can never have the same address, however a device can have more than one address.

To make the 32-bit form more compact and easier to read, Internet addresses are usually written in a decimal form with decimal points separating the byte

10000000 00001011 00000011 00011111

128. 11. 3. 31

Each IP address is a pair (Netid and Hostid) where netid identifies a network and the hostid identifies a host on that network.

Netid Hostid

IP Address classes

There are five different IP Address classes: A,B,C,D and E, they are designed to cover the need of different types of organizations.

Class A : the first 8 bits (Octet) defines the netid and the remaining 24 bits are used to define the hostid.

Class B : Two Octets define the netid and two defines the hostid.

Class C :Three octets define the netid and one octet defines the hostid

Class D : this class is for multicasting.

Class E : This class is reserved by the Internet for special use

Determining the class of an Address

From To

Class A 0.0.0.0 127.255.255.255

Class B 128.0.0.0 191.255.255.255

Class C 192.0.0.0 223.255.255.255 Netid Hostid Netid Hostid

Class D 224.0.0.0 239.255.255.255 Multicast Address Multicast Address

Class E 240.0.0.0 255.255.255.255

Reserved Reserved

Subnetting

• A subnet is a part of a network, which has the same network address as other parts of the network but a unique subnet number.

• Within the ISO/OSI reference model, the layers below the transport layer are referred to as the subnet (network, data link, and physical layers).

Why Subnet?

• Organization; use of different physical media; preservation of address space; security

• Most common reason: control network traffic – In an Ethernet network, performance can be adversely affected under heavy traffic loads.

Subnet Masking

• A subnet mask is used to determine what subnet an IP address belongs to.

• The subnet mask is the network address plus the bits reserved for identifying the subnetwork.

Subnetting: Example

• IP address 150.215.017.009

• Assuming this is part of a Class B network the first two numbers (150.215) represent the Class B network address, and the second two numbers (017.009) identify a particular host on this network.

• The IP address in binary format:

10010110.11010111.00010001.00001001

(Class B Network) (Host Address)

Subnetting: Example (cont’d)

• If the network is divided into 14 subnets, however, then the first 4 bits of the host address (0001) are reserved for the host.

• The subnet mask is the network address plus the bits reserved for identifying the subnetwork. By convention, the bits for the network address are all set to one, though it would it also work if the bits were set exactly as the network address.

Subnetting: Example (cont’d)Result

Subnet Mask

255.255.240.000 11111111.11111111.11110000.00000000

IP Address

150.215.017.009 10010110.11010111.00010001.00001001

Subnet Address

150.215.016.000

10010110. 11010111.00010000.00000000

Intranet

• A local area network (LAN) which may not be connected to the Internet, but which has some similar functions. Some organizations set up World Wide Web servers on their own internal networks so employees have access to the organization’s Web documents.

• Architecture / Security issues

Intranet Implementation

• Step 1: Define your needs

• Step 2: Choose your tool

• Step 3: Prepare and run the pilot

• Step 4: Prepare the rollout

• Step 5: Follow up closely and communicate

Intranet Issues

• What does my business gain?• How much will it cost now?• How much will it cost later?• Is it manageable?• How does it fit into my existing systems?• What kind of training will my developers and users need?• Can I outsource my intranet?• How will it affect productivity?• How secure is it?• How much time will it take to start one?