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Transcript
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 UTP Implementation (StraightThrough) Cable 10BASE-T/ 100BASE-TX Straight-Through Pin Label 1 2 3 4 5 6 7 8 TX+ TXRX+ NC NC RXNC NC 1 2 3 4 5 6 7 8 Straight-Through Cable Pin Label TX+ TXRX+ NC NC RXNC NC Wires on cable ends are in same order. UTP Implementation (Crossover) Cable 10BASE-T or 100BASE-TX Straight-Through Crossover Cable EIA/TIA T568A Pin Label 1 2 3 4 5 6 7 8 TX+ TXRX+ NC NC RXNC NC 1 2 3 4 5 6 7 8 EIA/TIA T568B Pin Label TX+ TXRX+ NC NC RXNC NC Some wires on cable ends are crossed. 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 – Redundant topology eliminates single points of failure. – Redundant topology causes broadcast storms, multiple frame copies, and MAC address table instability problems. Spanning Tree Protocol Block • Provides a loop-free (Loop Avoidance) redundant network topology by placing certain ports in the blocking state 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-oriented Connectionless Sequencing Fast delivery Acknowledgement Limited error checking Reliable delivery Unreliable delivery Session establishment Data recovery TCP UDP Comparison Clients Servers Any device that requests Any device that provides services from a remote access to resources application (offer services( Identifying Static and Dynamic Routing • 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 Comparison BRI PRI 2B+D 23B+D 128Kbps 1.544Mbps PSTN T1 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) OSI Model Overview Application Application (Upper) Layers Presentation Session Transport Layer Network Layer Data Link Physical 30 Data Flow Layers Layer 7 - The Application Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical •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 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 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical This layer is responsible for presenting the data in the proper format . - Compression & decompression of data Examples: AVI,JPG,…. Layer 5 - The Session Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical •Give orders for: establishment, management, and termination of the session between different application. •Specifies communication mode ( Half duplex – full duplex ) Layer 4 - The Transport Layer • 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical 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). Flow control Pc1 Pc2 Buffering Congestion avoidence stop Go on Layer 3 - The Network Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Responsible for: 1. End-to-end delivery. 2. Logical addressing . EX: IPv4,IPv6,IPX,APPLETALK 3. Routing (choose the best path to destination.) Layer 2 - The Data Link Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical 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 Layer 2 - The Data Link Layer •IEEE version ( IEEE 802.3 (MAC sub-layer) “Interact with physical layer” + IEEE 802.2 (LLC sub-layer) “Interact with Internet layer” ) Data-Link Layer Physical Layer IEEE 802.2 Logical Link Control sub-layer IEEE 802.3 Media Access Control sub-layer IEEE 802.3 Physical Layer Ethernet II 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. Layer 1 - The Physical Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical 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. Encapsulating Data Application Presentation Session Upper Layer Data TCP Header Transport Upper Layer Data IP Header Data LLC Header Data FCS MAC Header Data FCS 0101110101001000010 Protocol Data Unit (PDU) Segment Network Packet Data Link Frame Physical Bits De-encapsulating Data Application Presentation Session Upper Layer Data Transport Upper Layer Data Network TCP+ Upper Layer Data IP + TCP + Upper Layer Data Data Link LLC Hdr + IP + TCP + Upper Layer Data Physical 0101110101001000010 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 Application Layer Transport Layer F T P T E L N E T S M T P D N S T F T P S N M P R I P 21 23 25 53 69 161 520 TCP UDP Port Numbers TCP Three Way Handshake/Open Connection Host A 1 Host B Send SYN (seq=100 ctl=SYN) SYN received SYN received 3 Established (seq=101 ack=301 ctl=ack) Send SYN, ACK 2 (seq=300 ack=101 ctl=syn,ack) Address Resolution Protocol I need the Ethernet address of 176.16.3.2. I heard that broadcast. The message is for me. Here is my Ethernet address. 172.16.3.1 172.16.3.2 IP: 172.16.3.2 = ??? IP: 172.16.3.2 Ethernet: 0800.0020.1111 • Map IP • Local ARP Ethernet Reverse ARP I heard that broadcast. Your IP address is 172.16.3.25. What is my IP address? Ethernet: 0800.0020.1111 IP = ??? Ethernet: 0800.0020.1111 IP: 172.16.3.25 • Map Ethernet IP • 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 Overview • Segmentation • Flexibility • Security VLAN = Broadcast Domain = Logical Network (Subnet) VLAN Operation • 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. 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 cost Disadvantages: 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 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