What is the Network ? Two or more connected computers that can Share resources such as : Data Printer Application.

What is the Network?

Two or more connected computers that can

Share resources such as :

• Data

• Printer

• Application

Network types ( LAN , MAN , WAN )

– Three main networking technologies are used to connect computers and networks together:• Local area network (LAN)• Metropolitan area network (MAN)• Wide area network (WAN)

LAN

Used to network computers located in a limited geographical area such as a room, floor, or building .

Speed : 1Mbps , 100Mbps , 1Gbps , 10Gbps

MAN

A MAN is used to interconnect networks that are larger than a LAN but smaller than a WAN.

EXAMPLE OF A MAN

WAN

• Spans a large geographic area

• Defined as an internetwork that connects many LANs using service provider.

• Examples of WANs– The Internet

EXAMPLE OF A WAN

Topologies

Bus : physical

Star : physical

Ring : logical

Mesh : physical

Cable 10BASE-T/100BASE-TX Straight-Through

Pin Label Pin Label

1

2

3

4

5

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TX+

TX-

RX+

NC

NC

RX-

NC

NC

1

2

3

4

5

6

7

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TX+

TX-

RX+

NC

NC

RX-

NC

NC

Straight-Through Cable

Wires on cable endsare in same order.

UTP Implementation (Straight-Through)

Cable 10BASE-T or100BASE-TX Straight-Through Crossover Cable

Some wires on cableends are crossed.

Pin Label Pin Label

1

2

3

4

5

6

7

8

TX+

TX-

RX+

NC

NC

RX-

NC

NC

1

2

3

4

5

6

7

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TX+

TX-

RX+

NC

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RX-

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NC

EIA/TIA T568A EIA/TIA T568B

UTP Implementation (Crossover)

Repeater

A repeater

• is a device that regenerates and amplifies a signal, to counteract the effects of attenuation

HUB

HUB• is a device used to connect all of the

computers on a star network. • From the outside, a hub looks like nothing

more than a box with a series of cable connectors and LEDs in it

• Two Types: Active and Passive• Active :amplifies the signals and immediately

transmits them through all of the other ports. • Passive: transmits the signals through all of

the other ports .

Bridges

• Operate at Layer 2 of the OSI model

• Forward, filter, or flood frames

• Few ports

• Slow

Layer 2 devices

• A layer 2 device is a device that understand MAC, for example:

NIC (Network Interface Card) Bridge : - address learning - forwarding decisions are based on software - bridge is used for LAN segmentation - max. 16 port. Switch: - a multi-port bridge up to 567 port - forwarding decisions are based on hardware ASIC (faster than bridge)

functions of a switch

- Address learning

- Forward/filter decision

- Loop avoidance ( Loop free )

– Redundant topology eliminates single points of failure.– Redundant topology causes broadcast storms, multiple frame copies, and MAC address

table instability problems.

Redundant Topology

• Provides a loop-free (Loop Avoidance) redundant network topology by placing certain ports in the blocking state

Spanning Tree Protocol

Block

Router

functions of a router

-connect between networks

-Select best path

-Divide broadcast domain

-Packet forwarding

Identify Collision and Broadcast Domains

Collision domain =3 and Broadcast Domains=3

Identifying Collision and Broadcast Domains

Collision domain =8 and Broadcast Domains=5

Comparison

Connection-orientedConnectionless

SequencingFast delivery

AcknowledgementLimited error checking

Reliable deliveryUnreliable delivery

Session establishment

Data recovery

TCPUDP

Comparison

ClientsServers

Any device that requests services from a remote application

Any device that provides access to resources

))offer services

• Static Routing– Uses a route that a

network administrator enters into the router manually

•Dynamic Routing–Uses a route that a

network routing protocol adjusts automatically for topology or traffic changes

Identifying Static and Dynamic Routing

Comparison

BRIPRI

2B+D23B+D

128Kbps1.544Mbps

PSTNT1 Lines

OSI 7 layer

• OSI Open System Interconnection

We want the system to be standard to can any one use it

• ISO International Standard Organization

Make standarization to main task for operation ( IEEE)

30

OSI Model OverviewOSI Model Overview

Data Flow Layers

Transport Layer

Data Link

Network Layer

Physical

Application (Upper) Layers

Session

Presentation

Application

Layer 7 - The Application Layer•It’s the S\w on our pcs that is used to represent a user interface to the network & so aids the user to make applications.

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

7- Application Layer

• HTTP : Browsing protocol• FTP : File Transfer Protocol • TFTP : Trivial FTP• Telnet : Remote access protocol• SMTP : Simple Mail Transfer protocol • SNMP : Simple Network Management Protocol• DNS : Domain Name System• DHCP : Dynamic Host Configuration Protocol

Layer 6 - The Presentation Layer

This layer is responsible for presenting the data in the proper format .

- Compression & decompression of data

Examples:AVI,JPG,….

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

Layer 5 - The Session Layer•Give orders for: establishment, management, and termination of the session between different application. •Specifies communication mode ( Half duplex – full duplex )

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

Layer 4 - The Transport Layer• Responsible for actual

mechanism of:1. Establishment of connection.2. Management of connection: 2.1) segmentation. 2.2) sequencing. 2.4) error detection &correction. 2.5) flow control.3. Termination of connection.

Examples:• TCP (transmission control

protocol).• UDP (User Datagram Protocol).

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

Flow control

Pc1 Pc2

stop

Go on

BufferingCongestion avoidence

Layer 3 - The Network Layer

Responsible for:1.End-to-end delivery.2.Logical addressing .EX:

IPv4,IPv6,IPX,APPLETALK

3. Routing (choose the best path to destination.)

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

Layer 2 - The Data Link Layer

Responsible for:

1.Arbitration : find the best time to send the data

( CSMA/CD & taken) 2.Hop-to hop data delivery.3.Hop-to-hop addressing (MAC

Address in Ethernet).4. error detection 4.1- parity check : but very week 4.2-CRC : Depend on mathematical

equation

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

Layer 2 - The Data Link LayerData link sub-layers :LLC : (logical link control) places information in the frame that identifies which Network layer protocol is being used for the frame. MAC : (media access control) provide physical addressing and and delimiting of data according to the type of Data Link layer protocol in use.

•IEEE version ( IEEE 802.3 (MAC sub-layer) “Interact with physical layer” + IEEE 802.2 (LLC sub-layer) “Interact with Internet layer” )

Physical Layer

IEEE 802.2Logical Link

Control sub-layer

IEEE 802.3Media Access

Control sub-layer

IEEE 802.3Physical Layer

Data-LinkLayer

Eth

ern

et II

Layer 1 - The Physical Layer

It’s responsible for all Physical properties of the network :

1. Cable length.2. Cable type.3. Bit rate.4. Voltage levels.5. H/W interface types.

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

Encapsulating DataEncapsulating Data

Transport

Data Link

Physical

Network

Upper Layer Data

Upper Layer DataTCP Header

DataIP Header

DataLLC Header

0101110101001000010

DataMAC Header

Presentation

Application

Session

Segment

Packet

Bits

Frame

FCS

FCS

Protocol Data Unit (PDUProtocol Data Unit (PDU))

Upper Layer Data

De-encapsulating DataDe-encapsulating Data

LLC Hdr + IP + TCP + Upper Layer Data

MAC Header

IP + TCP + Upper Layer Data

LLC Header

TCP+ Upper Layer Data

IP Header

Upper Layer Data

TCP Header

0101110101001000010

Transport

Data Link

Physical

Network

Presentation

Application

Session

Protocols

• Ethernet • IP• IPX• TCP• UDP• TFTP• FTP• TELNET• SNMP• DHCP• DNS• SMTP

• PPP• Frame relay• ATM• HDLC• X.25

Commands

• Ipconfig/all

• Ipconfig/release

• Ipconfig/renew

• Ping

• Tracert

• nslookup

Port NumbersPort Numbers

TCP

Port Numbers

FTP

TransportLayer

TELNET

DNS

SNMP

TFTP

SMTP

UDP

ApplicationLayer

2121 2323 2525 5353 6969 161161

RIP

520520

Send SYN (seq=100 ctl=SYN)

SYN received

Send SYN, ACK (seq=300 ack=101 ctl=syn,ack)

Established(seq=101 ack=301 ctl=ack)

Host A Host B

1

2

3

SYN received

TCP Three Way Handshake/Open Connection

TCP Three Way Handshake/Open Connection

Address Resolution ProtocolAddress Resolution Protocol

• Map IP Ethernet

• Local ARP

172.16.3.1

IP: 172.16.3.2 Ethernet: 0800.0020.1111 IP: 172.16.3.2 Ethernet: 0800.0020.1111

172.16.3.2

IP: 172.16.3.2 = ???IP: 172.16.3.2 = ???

I heard that broadcast. The message is for me. Here is my Ethernet address.

I need the Ethernet address of 176.16.3.2.

Reverse ARPReverse ARP

• Map Ethernet IP

Ethernet: 0800.0020.1111IP: 172.16.3.25

Ethernet: 0800.0020.1111IP: 172.16.3.25

Ethernet: 0800.0020.1111 IP = ???Ethernet: 0800.0020.1111 IP = ???

What is my IP address?

I heard that broadcast. Your IP address is 172.16.3.25.

• IPv4 : 32 bit in decimal format

• IPv6 : 128 bit in hexadecimal format

• DLCI:10 bit

• MAC address:48 bit

IP Address classes

Private IP Addresses

Subnetting

• What is the subnetwork address for a host with the IP address 200.10.5.68/28?

• A. 200.10.5.56

• B. 200.10.5.32

• C. 200.10.5.64

• D. 200.10.5.0

Subnetting

• What is the broadcast address for a host with the IP address 192.168.221.37 255.255.255.248?

• A. 192.168.221.40

• B. 192.168.221.33

• C. 192.168.221.36

• D. 192.168.221.39

VLAN = Broadcast Domain = Logical Network (Subnet)

VLAN Overview

• Segmentation

• Flexibility

• Security

• Each logical VLAN is like a separate physical bridge.

• VLANs can span across multiple switches.

• Trunks carry traffic for multiple VLANs.

• Trunks use special encapsulation to distinguish between different VLANs.

VLAN Operation

802.1Q Frame

WIRELESS LANS

• IEEE standard 802.11 defines the specifications for wireless LANs (WLANs).

– Support ad hoc or infrastructure topologies

AD HOC WLAN

consists of two or more wireless devices communicating directly with each other

INFRASTRUCTURE WIRELESS

uses a wireless device called an access point between wireless devices and a standard cabled network.

FIREWALL SECURITY

• Firewalls protect a network from unauthorized access.

• Firewalls use several methods to examine network traffic for potential threats:

– Packet filtering– Port filtering

NAT

• NAT is a routing technique that enables computers with private IP addresses to connect to the Internet.

• The NAT router maps private to public addresses and vice versa.

• Security feature of NAT– Hides hosts on private networks

NAT MAPPING METHODS

• NAT routers can map private and public addresses using one of three methods:– Static

• One-to-one mapping (registered to unregistered), requiring many registered IP addresses

– Dynamic• Many unregistered addresses mapped to one or

more registered addresses– Overload

• Many unregistered addresses to one or more registered addresses using ports to differentiate connections

STATIC NAT

DYNAMIC NAT

Overload

PHYSICAL LAYER WAN CONNECTIONS

• Physical layer WAN connections use the following technologies:

– Leased lines

– Circuit switching

– Packet/cell switching

WAN Connection Types

Point to Point or dedicated connection

Benefits:

•High speed up to 45 Mbps• Secure

Disadvantages:

•High expensive•Limited availability

WAN Connection Types

Dedicated circuit path must exist between sender and receiver for the duration of the call.

Examples:

•Dial up•ISDN

Dial up

Benefits: Low costDisadvantages: Low speed (56Kpbs)

ISDN

ISDN

• The Integrated Services Digital Network (ISDN) uses the PSTN network.

• Uses circuit switching technology.

• Two main types of ISDN services: • Basic Rate Interface (BRI) • Primary Rate Interface (PRI)

BRI

• The ISDN BRI is referred to as 2B + 1D.

• BRI has– 2 channels for data, known as B channels– 1 channel for control (out-of-band signaling),

known as a D channel

• Each 64-Kbps B channel can operate independently or can be combined to offer a 128-Kbps transmission rate.

PRI

• The ISDN PRI service consists of– 23 channels for data, known as B channels– 1 channel for control (out-of-band signaling),

known as a D channel

PACKET SWITCHED WAN

Benefits: High speed up to 45 Mbps Not SecuredDisadvantages: Low cost High availability

Examples:•X.25•Frame relay

FRAME RELAY

• Frame relay is a data-link layer protocol that

– Uses Permanent Virtual Circuit (PVC) and Switched Virtual Circuit (SVC) connections

– Uses Data Link Control Identifier (DLCI) values to identify connections

– Supports data rates from 56 Kbps up to 45Mbps

cell switching WAN technology

• Asynchronous Transfer Mode (ATM) is a cell switching WAN technology.

• It is designed to carry voice, data, and video traffic.

• ATM uses fixed 53-byte cells.

• It supports data rates from 56 Kbps up to 45Mbps

Broad band Technologies

• DSL

• CATV

• satellite

DSL• Digital Subscriber Line (DSL) technology offers

higher transfer rates over standard telephone lines.

• DSL achieves higher data rates by using higher frequency ranges.

• Two types: ADSL :Asymmetric Digital Subscriber Line Download speed more faster than upload speed SDSL:symmetric Digital Subscriber Line Download speed equal upload speed

CATV

• Cable television (CATV) networks use broadband signaling.

• Multiple channels occupy a single cable.

• CATV uses asymmetrical transmission.

CATV CONNECTION

Satellite

• Satellite uses asymmetrical transmission.

• Upload speed 512Kbps

• Download speed 2.048Mbps

• Two methods:

• One way• Two way

WAN Encapsulation protocols

• Leased line: PPP , HDLC

• Circuit switched : PPP , HDLC

• Packet switched : X.25 , Frame relay

• Cell switched : ATM