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 TX+ TX- RX+ NC RX- NC TX+ TX- RX+ NC RX- NC Straight-Through Cable Wires on cable ends are in same order. UTP Implementation (Straight- Through)

Cable 10BASE-T or 100BASE-TX Straight-Through Crossover Cable Some wires on cable ends are crossed. Pin Label TX+ TX- RX+ NC RX- NC TX+ TX- RX+ NC RX- NC EIA/TIA T568AEIA/TIA T568B UTP Implementation (Crossover)

Repeater

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

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 Connectionless Connection-oriented Fast deliverySequencing Limited error checkingAcknowledgement Unreliable deliveryReliable delivery Session establishment Data recovery UDPTCP

Comparison ServersClients Any device that provides access to resources ((offer services Any device that requests services from a remote application

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+D 23B+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 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 Buffering Congestion 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 Layer Data 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 (MAC sub-layer) “Interact with physical layer” + IEEE (LLC sub-layer) “Interact with Internet layer” ) Physical Layer IEEE Logical Link Control sub-layer IEEE Media Access Control sub-layer IEEE Physical Layer Data-Link Layer Ethernet 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 Data Transport Data Link Physical Network Upper Layer Data TCP Header DataIP Header DataLLC Header DataMAC Header Presentation Application Session Segment Packet Bits Frame FCS Protocol Data Unit (PDU )

Upper Layer Data De-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 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 Numbers TCP Port Numbers FTPFTP Transport Layer TELNETTELNET DNSDNS SNMPSNMP TFTPTFTP SMTPSMTP UDP Application Layer RIPRIP 520

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 AHost B SYN received TCP Three Way Handshake/Open Connection

Address Resolution Protocol Map IP Ethernet Local ARP IP: Ethernet: IP: Ethernet: IP: = ??? I heard that broadcast. The message is for me. Here is my Ethernet address. I need the Ethernet address of

Reverse ARP Map Ethernet IP Ethernet: IP: Ethernet: IP: Ethernet: IP = ??? What is my IP address? I heard that broadcast. Your IP address is

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 /28? A B C D

Subnetting What is the broadcast address for a host with the IP address ? A B C D

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 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 cost  Disadvantages: Low speed (56Kpbs)

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 Secured Disadvantages: 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