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Welcome to network+Cisco ( CCNA, CCNP, CCIE, )Comptia (Network+, Server+, Linux+, Security+, e-Biz+, A+ )Microsoft (MCP, MCSE, MCSD,MCITP, .)Redhat Red Hat Certified Technician (RHCT).SUN Solaris

A requisite for CCNA CoursePassing the Network+ Exam and get the certificationRepresenting a solid background of networking knowledge regarding Network+ standard course

Basic Networking Fundamentals=Two or more computers connected together, having the ability to use shared resources on each other.

Two computers that are connected with a Network Cable through their network cards are an example of a simple network.

What is a Computer Network ?Something to share ( Data ) Physical Pathway ( Transmission medium ) Interfaces for communication ( Network Interface ) Rules of Communication ( Protocols )

In a clinent/server network each host will act Specifically as a Server (the provider of resources) or a Client (the receiver of resources)

What are some of the different types of the network?What are some of the different types of the network?

Peer to peerIn a peer to peer network every host will act as a client AND a server

What are some of the different types of the network?

LAN Local Area NetworkTypically refers to a network contained whitin a building

MAN Metropolitan Area Network A network spread between non-contiguous Buildings within a single metropolitan area.

WAN Wide Area NetworkA network spread over a wide area ,typically covering multiple cities and countries.

Network Types ( 2 )Network Topologies :

1 Bus 2 Star 3 Ring 4 Mesh (Full mesh Vs. Partial mesh) 5 -Tree 6 - Hybrid

Bus Topology

Star TopologyRing Topology

Mesh Topology

Tree Topology

Hybrid Topology

Network TypesTransmission Methods :

Circuit switching Dedicated path is created between two nodes

Packet switching Message is broken into small packets

Circuit SwitchingA circuit is established, an end-to-end connection must exist to transfer data

The actual data transfer

After data transmitted, connection is terminated

Packet SwitchingMessage is broken into small packets.Allows interactive exchanges because of small packets.Uses messages that are all the same length (called packets)

Network Terminology (1)ClientServerHostWorkstationPeer

Network Terminology (2)Backbone A part of a network that all segments and servers connect. (Gigabit Ethernet, FDDI, Thicknet) Segment Any short section of the network that is connected to the backbone

Network Terminology (3)Half-duplex A bi-directional communication but only one direction at a time, such as walkie-talkie Full-duplex Allows communications in both directions simultaneously.

Network Terminology (4) Broadband Vs. Baseband With baseband the whole bandwidth of the cable is used for each signal (channel), but in broadband the bandwidth is divided into descrete bands

PHYSICAL MEDIA

)Physical Media

CopperCoaxial Cable - Thick or ThinUnshielded Twisted Pair Optical FiberMultimodeSinglemodeWirelessShort RangeMedium Range (Line of Sight)Satellite

Copper Media: Coaxial CableCoaxial cable is a copper-cored cable surrounded by a heavy shielding and is used to connect computers in a network.Outer conductor shields the inner conductor from picking up stray signal from the air.High bandwidth but lossy channel.Repeater is used to regenerate the weakened signals.

CategoryImpedanceUseRG-5975 WCable TVRG-5850 WThin EthernetRG-1150 WThick EthernetCopper Media: Twisted PairTwisted-pair is a type of cabling that is used for telephone communications and most modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs. There are two basic types, shielded twisted-pair (STP) and unshielded twisted-pair (UTP).

Shielded Twisted Pair (STP)

Unshielded Twisted Pair (UTP)

Unshielded Twisted Pair (UTP)Consists of 4 pairs (8 wires) of insulated copper wires typically about 1 mm thick.The wires are twisted together in a helical form. Twisting reduces the interference between pairs of wires.High bandwidth and High attenuation channel.Flexible and cheap cable.Category rating based on number of twists per inch and the material usedCAT 3, CAT 4, CAT 5, Enhanced CAT 5 and CAT 6.

EIA/TIA 568A vs 568 B

Fiber MediaOptical fibers use light to send information through the optical medium.It uses the principal of total internal reflection.Modulated light transmissions are used to transmit the signal.

Total Internal Reflection

Light travels through the optical media by the way of total internal reflection. Modulation scheme used is intensity modulation.Two types of Fiber media :MultimodeSinglemodeMultimode Fiber can support less bandwidth than Singlemode Fiber.Singlemode Fiber has a very small core and carry only one beam of light. Fiber MediaSingle and Multimode FiberSingle-mode fiberCarries light pulses along single pathUses Laser Light SourceMultimode fiberMany pulses of light generated by LED travel at different angles

Network Terminology (5)Fiber-Optic CableContains one or several glass fibers at its coreSurrounding the fibers is a layer called cladding

Fiber Optic CableFO Cable may have 1 to over 1000 fibers

Fiber optic connectors

ST (Straight Tip) Connector.

Fiber optic connectorsSC Connector

Fiber optic connectors

MT-RJLCWireless MediaVery useful in difficult terrain where cable laying is not possible.Provides mobility to communication nodes.Right of way and cable laying costs can be reduced.Susceptible to rain, atmospheric variations and Objects in transmission path.

Installation typeInfrastructor

Installation typeAd-hoc

Unidirectional antennas

52Type of TransmissionUnicastMulticastBroadcast53Type of Transmission

54Broadcast DomainA group of devices receiving broadcast frames initiating from any device within the group

Routers do not forward broadcast frames55CollisionThe effect of two nodes sending transmissions simultaneously in Ethernet. When they meet on the physical media, the frames from each node collide and are damaged.

55Exam WatchMake sure you understand the mechanics of Ethernet: CSMA/CD. No device has priority over another device. If two devices transmit simultaneously, a collision occurs. When this happens, a jam signal is generated and the devices try to retransmit after waiting a random period.56Collision DomainThe network area in Ethernet over which frames that have collided will be detected. Collisions are propagated by hubs and repeatersCollisions are Not propagated by switches, routers, or bridges

56If two or more machines simultaneously sense the wire and see no frame, and each places its frame on the wire, a collision will occur. In this situation, the voltage levels on a copper wire or the light frequencies on a piece of fiber get messed up. For example, if two NICs attempt to put the same voltage on an electrical piece of wire, the voltage level will be different than if only one device does so. Basically, the two original frames become unintelligible (or undecipherable). The NICs, when they place a frame on the wire, examine the status of the wire to ensure that a collision does not occur: this is the collision detection mechanism of CSMA/CD.If the NICs see a collision for their transmitted frames, they have to resend the frames. In this instance, each NIC that was transmitting a frame when a collision occurred creates a special signal, called a jam signal, on the wire, waits a small random time period, and senses the wire again. If no frame is currently on the wire, the NIC will then retransmit its original frame. The time period that the NIC waits is measured in microseconds, a delay that cant be detected by a human. Likewise, the time period the NICs wait is random to help ensure a collision wont occur again when these NICs retransmit their frames.The more devices you place on a segment, the more likely you are to experience collisions. If you put too many devices on the segment, too many collisions will occur, seriously affecting your throughput. Therefore, you need to monitor the number of collisions on each of your network segments. The more collisions you experience, the less throughput youll get. Normally, if your collisions are less than one percent of your total traffic, you are okay. This is not to say that collisions are badthey are just one part of how Ethernet functions.Networking deviceObjectivesExplain the uses, advantages, and disadvantages of repeatersExplain the uses, advantages, and disadvantages of hubsDefine wireless access pointsDefine network segmentationExplain network segmentation using bridges58Objectives (continued)Explain network segmentation using switchesExplain network segmentation using routers59Brouters is a termRepeatersLength of cable used influence the quality of communicationRepeaters repeat signalsRepeaters only work with the physical signalCannot reformat, resize, or manipulate the dataPhysical layer (layer 1) deviceRepeaters (continued)

Repeaters (continued)

HubsGeneric connection devicePhysical layerConnect several networking cables togetherActive hubsMultiport repeatersPassive hubsHubs and topologyHubs (continued)

Advantages And Disadvantages Of Repeaters And Hubs

Advantages of using repeatersExtend network physical distanceDo not seriously affect network performanceDisadvantages of using repeatersCannot connect different network architecturesToken Ring and EthernetCannot reduce network trafficAdvantages And Disadvantages Of Repeaters And Hubs (continued)Disadvantages of using repeaters Do not segment the networkRepeat everything without discriminationNumber of repeaters must be limitedRepeaters are part of a collision domain

67Hubs & Collision Domains

More end stations means more collisions.CSMA/CD is used.67Tk-10-7Wireless Access PointsWireless local area networks (WLANs)Wireless access points provide cell-based areasContains radio transceiverFunction like a hubBandwidth is sharedMay also function as a wireless repeaterWireless clientsWireless Access Points (continued)

Network SegmentationProblems occur with too many nodes on the same network segment or collision domainNetwork Segmentation (continued)

BridgesOperate at the Data Link layerForward or drop framesCannot filter broadcastsMAC to segment # tableBridges (continued)

Advantages And Disadvantages Of BridgesAdvantages of using a bridgeReduce network traffic with minor segmentationCreates separate collision domainsReduce collisionsAdvantages And Disadvantages Of Bridges (continued)Disadvantages of using bridgesSlower due to filteringDo not filter broadcastsMore expensiveSwitchesOperate at the Data Link layerIncrease network performanceVirtual circuits between source and destinationMicro segmentation77Devices On Layer 2(Switches & Bridges)Each segment has its own collision domain.All segments are in the same broadcast domain.Data-Link

OR

12312

477 78SwitchesEach segment is its own collision domain.Broadcasts are forwarded to all segments.MemorySwitch

78TK16-1579

MAC Address TableInitial MAC address table is empty.79Slide 1 of 3Emphasize: The 1900en max MAC address table size is 1024. Once the table is full, it will flood all new addresses until existing entries age out.The command to change the MAC address table aging time is, as follows:wg_sw_a(config)#mac-address-table aging-time ? Aging time valueThe default is 300 sec.The MAC address table is also referred to as the CAM table (Content Address Memory) on some switches.

80

Learning AddressesStation A sends a frame to station C.Switch caches the MAC address of station A to port E0 by learning the source address of data frames.The frame from station A to station C is flooded out to all ports except port E0 (unknown unicasts are flooded).80Slide 2 of 381Learning Addresses (Cont.)Station D sends a frame to station C.Switch caches the MAC address of station D to port E3 by learning the source address of data frames.The frame from station D to station C is flooded out to all ports except port E3 (unknown unicasts are flooded).

81Slide 3 of 3Emphasize: Once C replies, the switch will also cache station Cs MAC address to port E2, as shown in the next slide.

82Filtering FramesStation A sends a frame to station C.Destination is known; frame is not flooded.

8283Station D sends a broadcast or multicast frame.Broadcast and multicast frames are flooded to all ports other than the originating port.

Broadcast and Multicast Frames8384Forward/Filter Decision When a frame arrives at a switch interface, the destination hardware address is compared to the forward/ filter MAC database.

If the destination hardware address is known and listed in the database, the frame is sent out only the correct exit interface

If the destination hardware address is not listed in the MAC database, then the frame is flooded out all active interfaces except the interface the frame was received on.

If a host or server sends a broadcast on the LAN, the switch will flood the frame out all active ports except the source port. Switches (continued)Advantages of switchesIncrease available network bandwidthReduced workload, computers only receive packets intended for them specificallyIncrease network performanceSmaller collision domainsSwitches (continued)Disadvantages of switchesMore expensive than hubs and bridgesDoes not filter broadcast trafficMethod of Switching - Cut Through ModeMuch fasterCannot detect corrupt packetsCan propagate the corrupt packets to the networkBest suited to small workgroups88Method of Switching - Store and Forward ModeRead the whole packet before transmitSlower than the cut-through modeMore accurate since corrupt packets can be detected using the FCSMore suit to large LAN since they will not propagate error packets

10MbpsDB100MbpsFacilitate data transfer between segments of different speed

89

Using Switches to Create VLANsSwitches can logically group together some ports to form a virtual local area network (VLAN)

Switches can be configured to communicate only within the devices in the group

HubHubHubSW1SW2SW3VLAN1VLAN2Switches (continued)

RoutersProvide filtering and network traffic controlUsed on LANs and WANsConnect multiple segments and networksMultiple routers create an internetworkOperate at the Network layerRouters (continued)Create a table to determine how to forward packetsFiltering and traffic control base on logical addressesPhysical Versus Logical AddressesMAC addressesData Link layer applicationUsed by switches, bridges, and routersUsed for directly connected devicesLogical addressesNetwork and transport protocols dictate the format of the logical network layer addressTCP/IP, IPX/SPXIP addresses are assigned manually or by softwarePhysical Versus Logical Addresses (continued)

Advantages And Disadvantages Of RoutersAdvantages of routersCan connect networks of different architectureToken Ring to EthernetChoose best path through or to a networkCreate smaller collision domainsCreate smaller broadcast domainsAdvantages And Disadvantages Of Routers (continued)Disadvantages of routersOnly work with routable protocolsMore expensive than hubs, bridges, and switchesRouting table updates consume bandwidthIncrease latency due to a greater degree of packet filtering and/or analyzingAdvantages And Disadvantages Of Routers (continued)

Static and Dynamic Routers

Layer-3 SwitchesLayer-3 switches operate in both layer 2 (data link layer) and 3 (network layer)Can perform both MAC switching and IP routingA combination of switch and router but much faster and easier to configure than router

Why Layer-3 switches?Traffic of LAN is no longer localSpeed of LAN is much fasterNeed a much faster router, however, very expensiveSummaryRepeaters are the least expensive way to expand a network, but they are limited to connecting two segmentsBridges function similar to repeaters, but can understand the node addressesSwitches can be considered as multiport bridges, can divide a network into some logical channelsRouters interconnect networks and provide filtering functions. They can determine the best routeRemote Access Devices

1. Modems

Cannot send digital signal directly to telephone lineSending end: MODulate the computers digital signal into analog signal and transmits Receiving end: DEModulate the analog signal back into digital form

ADSLADSL stands for Asymmetric Digital Subscriber LineParticularly suitable for high speed multimedia communications, general Internet applicationsAsymmetric - downstream 1.5 to 6.1Mbps upstream 16 to 640kbpsDigital - mainly for transmitting digital data still require modulation and demodulationSubscriber line - make use of the analog connection between household and COB

TelephoneCompany2 to 3 milesSplitter

datahigh speedlow speedADSL Illustrationsubscriber linelocal loopWhy Asymmetric?In general Internet applications, downstream often requires a higher data rate than upstreamDownstream - file download, video playbackUpstream - click a link, send a form

Reducing the resource for upstream can provide more resource for downstreamADSL exploits the unused analogue bandwidth available in the wires

ADSL works by using a frequency splitter device to split a traditional voice telephone line into two frequencies PSTNDownstreamUpstreamNetwork Terminology (5)Architecture of ADSL Services

ISPCentral OfficeSubscriber premisesVoice Switch DSL

Static RoutersDynamic Routers

Manual configuration of routesManual configuration of the first route. Automatic discovery of new routes

Always use the same routeCan select the best route

More secureNeed manual configuration to improve security